Astr Final Cheat Sheets (1)

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Astronomy

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Dec 6, 2023

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(diagram shows the rota/on curve for the Milky Way. 1 km/s = 1000 m/s) 1 ly = 9.46 x 1015m. mass of the Sun = 2 x 1030kg. 1 x 10^11 Msun (diagram shows the rota/on curve for the Milky Way. 1 km/s = 1000 m/s) From the Sun, the distance to the Galac/c Center is about 8,000 pc 1.4x10 9 m? -26.7 -1.5 magnitude Sirius appears 25x brighter than second magnitude Polaris T A blue star has a higher surface temperature than a red star. T A blue star with a peak wavelength in the UV has a higher surface temp than a red star with a peak wavelength in the IR T According to the universal law of gravita/on, if you double the masses of both aVrac/ng objects, then the gravita/onal force between them will - increase by a factor of 4. According to Newton's second law (F=ma), if you double the force ac/ng on a body, the accelera/on will double True A main sequence star has an absolute magnitude of 2. What would be the approx. luminosity of the star and what would be the spectra class? – 13.5 Lsun; spectral class A A planet or comet will speed up as approaching the sun? True A skater can spin faster by pulling her arms closer to her body or spin slower by spreading her arms out from her body. Assume a skater pulls her arms in and her speed increases by a factor of 3. What can be said to be true. The radius of spin decreased by a factor of 3. A solar mass star will evolve off the main sequence when It builds up a core of inert helium A television adver/sement claiming that a product is light years…… it uses “light years” to talk about Lme, but a light-year is a unit of distance A type B9 star is hoVer than a type A0 T According to Wein's law, the wavelength of the peak energy will be ________ if the temperature of the blackbody is doubled . - halved According to Hubble's Law, the greater a galaxy's redshib,the farther it is from us According to Newton’s law of universal graviatoin, if the M were 6x further from E, the force by E on the M would decrease by a factor of 36 According to the Hubble Law graph shown, a galaxy cluster with a recessional velocity of 25,000 km/s will be 400 million pcs away According to the inverse square law of light, how will the apparent brightness of an object change if its stance to us triples? Its apparent brightness will decrease by a factor of 9 According to Wein’s law, the higher the surface temperature of a star,the redder its color F According to Wein’s Law if the surface temp is increased by a factor of 6 its peak wavelength will decrease by a factor of 6 According to Wein's law, the wavelength of the peak energy will be ________ if the temperature of the blackbody is doubled. : Halved According to the universal law of gravita/on, if you double the masses of both aVrac/ng objects: then the gravitaLonal force between them will increase by a factor of 4 A circular orbit would have an eccentricity of 0 A comp accessory salesman aVempts to convince Neutrinos rarely if ever interact with your computer Aber a massive-star supernova, what is leb behind? either a neutron star or a black hole Aber a supernova event, what is leb behind? either a neutron star or a black hole A high-mass star dies more violently than a low-mass star because it generates more heat a liTle over a million All but one of the following statements describe why scien/sts doubt the solar sunspot cycle affect global climate Solar winds can affect satellite communicaLon All neutron stars are pulsars, but not all pulsars are neutron stars. F All of the following statements are true. Which one explains the reason why there is not a solar eclipse at every new moon? The orbital plane of the m is Llted by 5 all others All radio telescopes are reﬂectors in design T All stars spend approximately the same amount of /me on the main sequence F All stars that become supernovae will leave behind a neutron star F All the following statements are true. Which one explains the reason that there is not a solar eclipse at every new Moon? The orbital plane of the moon is Llted slightly (about 5 degrees) to the eclipLc plane A loop of gas and charged par/cles following the mag field lines between sunspots poles is a prominence/filament Although it is diﬃcult to tell from our vantage point inside the galaxy, MW spiral T A main sequence star of 8 solar masses will be approx. 4000x more luminous than the Sun. T ? and its core eventually collapses very suddenly? An O-star has a hoVer surface temp than the S, Therefore compared to the S its emission peaks in the blue part of the spectrum A par/cular nebula is a hot, thin cloud of glowing gas, so its emission spectrum looks like f=8.9x10^14hz and E=5.9x10^-19J A par/cular star has an absolute magnitude of M=-0.3. Determine the lum… Spica A par/cular star has an angle of parallax of 0.1 arcsecs. What is the distance about 33 ly A par/cular star in a binary star systems orbits the other with an average orbital radius of 3AU and a period of 5 yrs. What is the sum of the masses of the 2 radius 1.1 A planet (or comet) will speed up as it approaches the Sun T A planet whose distance from the Sun is 5 AU would have an orbital period of how many Earth-years? √125 A planet whose distance from the S is 3 A.U orbital period = √ 27 A planet whose distance from the Sun is 18 AU orbital period = 76 Apparent magnitude is a measure of a star’s brightness, as seen form Earth. apparent magnitude is m=3.75. 224 pc Approximately how far is the Sun from the center of the galaxy? 27,000 light-years A protostar moves onto the main sequence with a mass of 0.18 solar masses. the luminosity of the star and hence its spectral type. M A protostar moves onto the main sequence with a mass of 3.2 (or 5.6) solar masses. the luminosty of the star and hence its spectral type. B A protostar moves onto the main sequence with a mass of 3.2 solar masses B A protostar of 50 solar masses will probably turn into a type O main sequence star. T A protostar of 50 solar masses will probably turn into a type O main sequence star T A pulsa/ng variable star w/period of 10d would be a Cepheid hve abs mag of -4.2 T A pulsa/ng variable star w/period of 50d would be a Cepheid hve ab smag of -6.3 T A radio telescope (collects radio light waves) and an op/cal telescope (collects visible light) of the same size have the same angular resolu/on F A radio telescope and an op/cal telescope of the same size have the same D F around Earth. As a star begins to evolve away from the main sequence, it gets larger T A sidereal year is defined as the Lme it takes for Earth to complete an orbit around the Sun. As it moves in its orbit, Earth is always exactly 1AU from the Sun F A solar eclipse can occur only when the Moon is new. T A solar eclipse can only occur when the Moon is new T As originally stated, the Copernican model did no beVer a job of predic/ng planetary behavior than did the Ptolemaic one. Hence neither model could be “disproved” T Assume that in the future, a telescope is built on Europa and measures a parallax of 1.3” Procyon lies about 13 light years distant. What must be the baseline 5.2AU A star (no maVer what its mass) spends most of its life: as a main sequence star A star has an absolute magnitude of -6 and an apparent magnitude of +12. What is the distance to the star? 40,000pc A star has an apparent magnitude of 3 and an absolute magnitude of -1. Determine the distance to the star. – 63 parsec A star has an apparent magnitude of +7 and an absolute magnitude of -4. What is the distance to the star? 1585 pc A star has a space velocity of 15 km/sec and a transverse velocity of 12 km/ sec….redshibed… The radial velocity is 9 km/s away from Earth A star is on the horizontal branch of the H-R diagram.true? burning both hydrogen& helium A star of ½ sun’s diameter, but twice as hot, would be 4x more luminous than the sun T A star of apparent magnitude +5 appears fainter than a star of apparent magnitude +3 A star of ten solar masses would probably stay stable on the main sequence only about 1/1000th as long as our Sun. T A star of ten solar masses would probably stay stale on the main sequence only about 1/1000th as long as our Sun T A star of the Sun's diameter, but three /mes as hot, must be 81X more luminous than the Sun. T A star of the Sun's diameter, but twice as hot, must be 16X more luminous than T A star of the S’s diameter but 5x hoVer must be 625x more luminous than the S F A star’s abs mag and its app mag have the same numerical value. How far is this star 10pc A star with a parallax angle of 0.05" is – 20 parsec away. Aprox 3.24x more As the sun evolves into a red giant in the distant future with a surface temp of about 2000K, its peak on the Planck curve will move into the infrared A supernova occurred 10,000 years from now in a galaxy 50,000 light years away will be observed on earth 40,000 years from now A supernova that occurred 30,000 years ago in a galaxy 100,000 light years away will be observed on Earth 70,000y from now A supernova occurred 60,000 years ago in a galaxy 20,000 light years away. When was/ will be the event observed on Earth? 40,000 years ago As we look at larger scales in the universe, we find a larger and larger percentage of the maTer is dark At apogee the moon is at its farthest from earth and thus appears smaller than normal. Because of this it has the smallest angular size in the sky at this /me. T A telescope with a 600 mm objec/ve lens collects how many /mes as much light as does your eye's 6 mm exit pupil? 10,000X

At perigee the moon is at its closest from earth and thus appears larger than normal and is moving fastest in its orbit around earth T At the distance of Jupiter (6 /mes further away from the Sun than Earth) the amount of sunlight received per square cen/meter is different by what factor? 36 Lmes less At the distance of Jupiter the amount of sunlight received per square cen/meter different by what factor: 12 Lmes less At very large distances from the Sun, its corona turns in to the solar wind. T At which of these Kelvin temp would a blackbody radiate400-700nm 6000K A type A9I star is the same temperature as a type A9V star. T A year is defined as the Lme it takes for Earth to complete an orbit around the Sun Based on current es/mates of the value of Hubble's constant, how old is the universe? 12-16 billion years old Because they all involve the detona/on of a carbon-rich white dwarf at Chandrasekhar's limit, all type I supernovae are equally luminous and hence are excellent standard candles. T Betelgeuse is the bright red star represen/ng the leb should of the constella/on Orion. All the following statements about B are true. Which one can you infer from its red color? The peak intensity of radiaLon is likely in the IR range. By approximately how many x dimmer is the star Sirius (m=-1.7) than the full Moon (m=-13) in our sky? 33,000x dimmer By what mechanism does solar energy reach the Sun's photosphere from the layer just Calculate the diffrac/on limit if the Hubble Space Telescope is using a green filter of 556nm and has a diameter of 10 meters 0.014 arcsec Careful measurements reveal that a star maintains a steady app brightness at most /mes expect that a precise interval of 127 the star is a member of eclipsing Colors appear different to us because of their photons' different: frequencies Compared to a cluster containing type O and B stars, a cluster with only type F&cooler stars will be older Compared to the star it evolved from, a red giant is cooler and brighter Compared with our sun, most stars in the halo are: Old, red and dim and have fewer heavy elements. Compared with stars in the disk, orbits of stars in the halo are ellipLcal, with random orientaLon Consider HR diagram ONE on the cover sheet. Find Capella and the Sun. Es/mate how many /mes bigger or smaller Capella than Sun between 9 and 10x bigger Consider the HR diagram on the cover sheet of the exam, which of the following lists if the correct sequence of stars in order of increasing intrinsic brightness Procyon B, Sirius B, the sun, Deneb Consider the image below which shoes the top of the convec/on zone….If one par/cular spectral line has a rest wavelength of 480.00 nm, what is the measured wavelength of the same line from the diagram? 480.48 nm Consider the images below which shows the top of the convec/on zone of the Sun. The paVern of rising hot gas cells all over the photosphere is called sunspots Consider the HR diagram shown here. What would be the likely classifica/on of star B: G8III Consider this diagram, which statement is true, updown4, lebright6 the wavelength is 6 Consider this diagram. Which statement is true? The amplitude is 4. Constella/ons are close clusters of stars, all at about the same distance from the Sun. F Constella/ons are close clusters of stars, all at about the same distance from the Sun. F Constella/ons r close clusters of stars all at about the same distance fromS F Copernicus’s S centered model of the SS gave much beVer predic/ons than Ptolemy F Degeneracy pressure is the source of the pressure that stops the crush of gravity in all the following except a very massive main-sequence star. Detailed measurements of the disk and central bulge region. According to Hubble's classifica/on, the Milky Way would most likely be classified as SBb Detailed measurements of the disk and central bulge region of our Galaxy suggest our Milky Way is a barred spiral galaxy detec/on of neutron stars has been compared to observing a lighthouse. in the lighthouse model, the star literally turns on and off like a lighthouse beacon Determine the eccentricity of this ellipse if one of the foci is at x=2 0.4 Determine (calculate) the Hubble class for this ellip/cal galaxy.I have approx. outlined the galaxy with an ellipse and a ruler is provided. E3 Determine the orbital period of Neptune if the syno/c period is 1.00616 years. 164 yrs Determine the orbital period of Uranus if the syno/c period is 1.013 yrs 84 yrs Doubling the distance between 2 objects halves the gravita/onal force btw F During the Hydrogen shell burning phase: The star grows more luminous Dr. Smith believes H0 =70 km/s/Mpc. Dr. Jones believes H0 = 50 km/s/Mpc. Dr. Smith believes that the universe is younger than Dr. Jones believes. Dr. X believes that the Hubble constant is H0 = 55 km/s/Mpc. Dr. Y believes it is H0 = 80 km/s/Mpc. Dr. X believes that the universe is older than Dr. Y believes. During the period each year when we see Mars undergoing apparent retrograde mo/on in our sky, what is really going on in space? Earth is catching up with and passing by Mars in their respecLve orbits. Each choice below lists a spectral type and luminosity class for a star. Which one is a redgiant? Spectral type m2 , luminosity class I Earth is always precisely 1AU from the Sun all year around F Energy from the core of the S first travels slowly through a convec/on zone and then much faster through the outer radia/on zone. F Energy from the core of the Sun first travels slowly through the convec/on zone and then much faster through the radia/on zone F Eventually, all low mass stars will become white, then black, dwarfs. T Every red dwarf star (M<0.01MSun) that ever joined the main sequence is s/ll there today T Every second, the Sun converts about 600 million tons of hydrogen in 596 million tons of helium. the remaining 4 million tons of mass is converted to an amount of energy=4 million tons Lmes the speed of light squared Everything looks red through a red filter because the filter transmits red light and absorbs Except for hydrogen and most of the helium, all the elements have been formed through stellar nucleosynthesis. F For a nova or a Type 1a Supernova to occur, the system must have already been a mass- transfer binary For a star of 10 solar masses, its main sequence life span will be only 1/1000th of the sun For our Sun, the produc/on of carbon will be the end of its nucleosynthesis T For this ques/on, see the parallax equa/on on the coversheet for the baseline of Pluto’s orbit. The semimajor axis of Pluto’s orbit is 40AU,0001arcsec 40,000 pc From Earth, the S and M have about the same ang distance. Hence, during a solar eclipse the M just barely blocks the sun’s disc allowing for the outer atmosphere of the sun to be observed T From hoVest to coolest, the order of the spectral types of stars is - OBAFGKM . From Kepler's third law, a hypothe/cal planet that is twice as far from the Sun as Earth should have a period of more than 2 Earth years. From Kepler 3 rd law, an asteroid with an orbital of 8 yrs 4 astronomical units From laboratory measurements, we know that a par/cular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a par/cular star shows the same hydrogen line appearing at a wavelength of 121.8 nm. What can we conclude? The star is moving away from us at about 500 km/s. From laboratory measurements, we know that a par/cular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a par/cular star shows the same hydrogen line appearing at a wavelength of 122.8 nm. What can we conclude?- the star is moving away from us at approx 3000 km/s From the center outward, which of the following lists the "layers" of the Sun in the correct order core, radiaLon zone, convecLon zone, photosphere, chromosphere, corona Galaxies look the same whether viewed in visible or X-ray wavelengths. F Galileo's observa/ons of the en/re phase cycle of Venus, of the moons of Jupiter, of the scarred surfaces of the Moon, of Sunspots on the Sun, etc. all were crucial pieces of evidence that helped solidify the Copernican Revolu/on. T Galileo observed the phenomenon of solar rota/on in the early 1600s measuring the moLon of sunspots across the solar surface Galileo’s observa/ons of sunspots proved the Sun was rota/ng, like the Earth. T Gamma Rays are a type of electromagne/c radia/on produced in stars. T Given: the planets orbi/ng the nearby star 51 Pegasi, 20x, 400x, M=5.98 x 10^24, R= 6.37x 10^6 , weight = the same as you do here Granula/on is the most obvious proof of solar convec/ve energy transport. T Granula/on is the most obvious proof of solar convec/ve energy transport T Grass (that is healthy) looks green bc it reﬂects green light and absorbs other colors Grass is green because it absorbs green light, reﬂec/ng all other colors F Green light has a shorter wavelength than orange light. In a 5 inch Newtonian Reﬂector Telescope, green light will: provide beTer angular resoluLon than orange light Halving the distance between two objects doubles the gravita/onal force between them False Harlow Shapley concluded that the sun was not in the center of the milky way galaxy by mapping the distribuLon of globular clusters in the galaxy have a period of more than 2 yrs HenrieVa LeaviV first showed the rela/onship between the mass and luminosity of Cepheids and their period of pulsa/on; the brighter, the longer this period. T HenrieVa Swan LeaviV first showed the rela/onship between the mass and T history of the universe than Galaxy 2 How are the event horizon and Schwarzschild radius related? The Schwarzschild radius is equal to the distance from the singularity of a black hole to the event horizon. How are wavelength, frequency, and energy related for photons of light? Longer wavelength means lower frequency and lower energy.

How much stronger is the gravita/onal pull of the Sun on Earth, at 1 AU, than it is on Saturn at 10 AU? 100X How much stronger is the gravita/onal pull of the Sun on Earth, at 1 AU, than it would be if Earth were at 10 AU 100X How can we characterize the rota/on of the S? differenLal rotaLon with the equator rotaLng faster than the poles. How did Edwin Hubble measure the distance to the Andromeda Galaxy? He applied the period-luminosity relaLon to Cepheid variables How did the Ptolemaic model explain the apparent retrograde mo/on of the planets? It held that the planets moved along small circles that moved on larger circles around earth How does the light-collec/ng area of an 8-meter telescope compare to that of a 2-meter telescope? The 8 meter telescope has 16 Lmes the light-collecLng area of the 2-meter telescope How do we know that halo stars are older, on average, then disk stars? There are no Blue halo stars how is the sunspot cycle directly relevant to us here on earth? coronal mass ejecLons and other acLvity associated with the sunspot cycle can disrupt radio How long does the Sunspots cycle last on average? About 11 years How long is the precession cycle? 26000 years How many stars could you see with your naked eye on a clear, moonless night from a dark loca/on? A few Thousand How many planet Earths could fit inside the Sun? Rsun=109REarth about 5 million How many planet Earths could fit inside the Sun?v=4/3πR^3 diameter=109 Earth dia a liTle over a million How was Edwin Hubble able to use his discovery of a Cepheid in Andromeda to prove that the “spiral nebulae” were actually en/re galaxies? from the period-luminosity relaLon for cepheid How would you expect a star that formed recently in the disk of the galaxy to differ from one that formed early in the history of the disk? It should have a higher frzcLon of elements heavier than hydrogen and helium Hydrosta/c equilibrium in our Sun is the balance between gravitaLon and pressure If a material is highly opaque, then it absorbs most light If a source of light is approaching us at 3000 km/sec, then all waves blue shiped by 1% If a star has a parallax of 0.05°, then its distance in light years is about 65 light years If a star were moved 10 /mes farther away, its abs mag would drop 5 magnitudes. T If a wave’s frequency doubles, its wavelength is halved If Star A is closer to us than Star B,then Star A’s parall angle is larger than that of Star B If the distance between us and a star is doubled, the apparent brightness is decreased by a factor of four. T If the distance between us and a star is increased by a factor of 5, the apparent brightness is decreased by a factor of 25. T If the Hubble Constant is 70 km/sec/Mpc, the accelera/ng universe is about 5 billion years old. F If the rest wavelength of a certain spectral line is 600nm, but we observe it at 700nm/ 594nm then the source is moving away form us at 50,000/the source is approaching us at 1% of the speed of light If the S-E separa/on was 10AU instead of 1AU what would the ﬂux of sunlight 100x less If the source of light is approaching us at 3,000km/s, then all waves blue shiped by 1% If the star rises about 9PM 2nite and with the sidereal day being 4mins less T If the sun were replaced by a one solar mass black hole we would sLll orbit it in a period of one year If the temp of the solar surface is 5800K and Wien’s law for the peak t=2.9X10^6 500nm If we have a new Moon today, when we will have the next full moon? In about 2 weeks If we observe one edge of a star to be redshibed and the oppoite edge to be blue shibed what can we conclude about the star? The star is rotaLng If you are in the Moon's umbral shadow, then you will witness a total solar eclipse Improvements in tech will eventually allow the en/re electromagne/c F In 1924, Edwin Hubble proved that the Andromeda Galaxy lay far behind the bounds of the milky way...how was he able to prove this? He proved this by observing individual Chepheid variable stars in Andromeda and applying the period-luminosity relaLon. In a binary system, the less massive star always remain farther from the center of mass T In a binary system, the more massive stars always stay closer to the center of mass and move slower T In addi/on to the condi/ons required for any solar eclipse what must also be true to observe a total solar eclipse? The moon’s umbra must touch the area In a spectroscopic binary, if a pair shows a combined set of lines tonight, but a max split of two nights later, its orbital period must be 4days In a spectroscopic binary system, one star shows a large blue shib and the other is showing a small redshib. What conclusion can be drawn from this informa/on? The less massive star is approaching us at this moment In a spectroscopic binary, the star whose lines shib the most weighs the most. F In a spectroscopic binary system, the star showing the larger blue shib is less massive and approaching us at this moment In astronomy, an interferometer can be used to improve the angular resoluLon of radio telescopes In class we modeled the solar system using a yellow ball for the Sun (1 to 10 billion scale). On this scale, it would take about 10 - 15 minutes to walk from the Sun to the inner edge of the Kuiper Belt (Pluto). For reference the distance from the Earth the Sun is 1 AU and the distance to Pluto is about 70 AU. True In order to turn a star’s proper mo/on into its space velocity, we must also know: its distance and radial velocity In the HR diagram on the cover sheet of the exam, which is correct sequence of increasing temperature? Sun, Procyon b, Deneb, Sirius B In the lighthouse model: If the beam sweeps across us, we will detect a pulse of radiaLon. In the previous ques/on one star is exhibi/ng a blue shib, the other is exhibi/ng a redshib (has a picture) . 4:1, 4:1, 8, 20 AU 158 years In the proton-proton cycle, .007 of the mass ends up as energy, with the remaining mass ul/mately becoming helium. T In the proton-proton cycle, 0.007% of the mass ends up as energy, not helium T In the proton-proton cycle, the helium atom and neutrino have less mass than the original hydrogen. What happens to the “lost” mass it is converted to energy In the proton-proton cycle, you must first make deuterium then helium T In the sobball model of the ss it would take a few minutes 2 walk from the T In what range of masses are most stars found? .1 to 100 solar masses It is diffrac/on that limits the resoluLon of a telescopes objec/ve It is impossible to tell the difference between the two types of supernovae. False It is much easier to build large reﬂec/ng telescopes than large refrac/ng T It is now believed the majority of mass for most galaxies lies in their dark halos. T It is possible to view the M in first-quarter phase the same day as a total F It the radius of a body were doubled, its gravita/onal pull would become 4X stronger. F It took 2 centuries for the Copernican model to replace Ptolemaic model bc there was no scienLfic evidence to support either model 5 It took two centuries for the Copernican model to replaced the Ptolemaic model b/c there was no scienLfic evidence to support either model unLl galileo made his observaLons It was the distribu/on of globular clusters that showed Harlow Shapley we were no Johannes Kepler analyzed data gathered by Tycho and discovered that the T Jupiter is 300x more massive than earth. How much stronger is the gravita/onal pull of the sun on earth at 1au than it is on jupiter at 5au? 12x Kepler’s 1 law worked where Copernicu’ original heliocentric model failed bc ellipLcal, not circular Kepler’s 2 nd law implies what about planetary mo/on? A planet moves faster when closer to the sun Kepler’s 3 rd law, p2=a3 means that all the above are correct Kepler’s first law worked, where Copernicus’ original heliocentric model failed, because Kepler described the orbits as ellipLcal, not circular Light leaving a point source spreads out so that the app brightness b of light per unit area varies with distance d according to which of the following laws b ∞ 1/d^2 Lines of a par/cular element appear at the same wavelength in both emissi T Locate Procyon A on HR diagram 3 of the cover sheet. Es/ma/ng the surface temperature, determine the peak wavelength of radia/on coming from the surface if this star- 29nm Locate Rigel and Betelgeuse on HR Diagram 1 on the cover sheet. Both stars have approximately the same luminosity, but different temperatures. Apply the Stefan- Boltsmann rela/on to es/mate how many /mes bigger Betelguese is than Rigel. Approximately 45 Lmes larger. Locate Regulus on the HR diagram on the cover sheet and es/mate the luminosity rela/ve to the S. if the surface temp of Regulis 12,500k, 5800k, 2.2Rsun Low mass stars should produce white dwarfs, while high mass star will produce more compact and dense end product s T Lunar eclipses are more commonly seen than solar eclipses T Massive, more luminous stars have shorter lives than their smaller, dimmer counterparts. True Mass transfer in binaries occurs when one giant swells to reach the Roche Lobe Mean temperature in Europe during the Maunder min when virtually no lower than avg Mercury, with a higher eccentricity orbit, should change its orbital speed more than do Venus or Earth T Mercury, with a higher eccentricity orbit, should change its orbital speed as a percent more than do low eccen/city Venus or Earth True Modern astronomers have observed the complete life cycle for many stars, making stellar evolu/on one of the best-tested astronomical theories.: False Most of the current star forma/on in the Milky Way occurs in spiral arms T Most stars are born in clusters containing hundreds to thousands of stars T

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Neutron stars do not have rotaLon periods comparable to the sun’s Neutron stars have extremely high density.V=4/3πR^3,2 solar masses, 21.6km, 2x10^30kg. density? 9x10^26kg/km^3 No maVer where you live on E, the Sun is always directly overhead at noon F Observa/ons of the cosmic background radia/on from the COBE satellite revealed /ny observed on Earth 40,000 years from now Of all the forms of electromagne/c radia/on, the one with the lowest f is radio waves On a Hertzsprung-Russell diagram, where would we find red giant stars? upper right On an H-R diagram, a protostar would be: Above and to the right of the main sequence On a HR diagram, where would you find stars that are cool and dim? Lower right On an HR diagram, where would you find stars that are hot but not very luminous? Lower lep On an H-R diagram, stellar radii increase diagonally from the lower lep to upper right one. T One light-hour is the distance that light travels in an hour. How far in this in kilometers? 1.08 billion km One reason for building telescopes on mountain tops is that they improve seeing by reducing the amount of air above the observer T On the cover sheet locate Capella on HR diagram 1. Taking values from the graph, calculate approximately how many /mes larger Capella is than the Sun. 9x larger than the Sun On the cover sheet there is an ellipse. Determine the ecentricity of this ellispse. 0.75 On the H-R diagram a star classified as M2Ia would be located at the top right On the H-R diagram, red supergiants like Betelguese lie at the top right On the H-R diagram, the sun lies about the middle of the main sequence On the main sequence, almost all stars have radii between about 0.1 and 10 /mes the Sun. T Open clusters and young stars are generally found only in the disk of the galaxy T Open clusters and young stars are generally found only in the disk of the galaxy and not in the halo. True Op/cal telescopes are usually used only at night but radio telescopes T Our Milky Way is now known to be quite similar to the nearby Andromeda Galaxy, M-31. T Our solar system consists of the sun and all the objects that orbit it Our sun is a star of spectral type G Our Sun will end its life in a planetary nebula and become a white dwarf T Over the course of a night, Polaris moves less than any other visible star T Over the course of a night in the Northern Hemisphere, Polaris moves less than any other visible star in the sky. T Over the course of a night in the Northern Hemisphere, Polaris moves less than any other visible star in the sky. T Over /me, the star-gas-star cycle leads the gas in the Milky Way to have a greater abundance of heavy elements. Perhaps the greatest of the Greek Astronomers, Hipparchus complied the first catalog of stars accurately measured their posi/ons 16000pc photosphere at 570 nm is: 5800 Procyon lies about 13 light years distant, thus its parallax is about 0.25” Professional astronomical telescopes generally have a much greater magni F Recall that Hubble's law is wriVen v = H0d, Suppose H0 = 65 km/s/Mpc. 500 megaparsecs distant 32,500 km/s Recall that Hubble’s law is wriVen v=H0d, where v is the recession velocity of a galaxy. H0=65 km/s/mpc galaxy located 500 megaparsecs distant be receding form us? 32,500 km/s Refer to the figure which is the expected evolu/onary path of the Sun. What happens at posi/on 9? Helium ﬂash Refer to the figure which represents the expected evolu/onary path of the Sun. What phase represents the planetary nebula phase? 12 Regulus is at a distance of 24pc and has a radial velocity of 6.1km/s. Determine the proper mo/on of Regulus if the space velocity is 28.3 0.24 arcsec/yr Rota/on curves for spiral galaxies show most have dark halos Scien/sts today do not accept the Ptolemaic model bc the work of Tycho and Kepler showed the heliocentric model was more accurate Shapley found that globular clusters are only found in the Galac/c bulge. F Shapley used the distribu/on of globular clusters in the galaxy to determine that the Sun was not at the center of the Milky Way T Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude? Rigel has a higher surface temperature than Sirius Spectral lines are oben referred to as stars fingerprints bc all of these are √ Spectral Lines are produced when an electron makes a transi/on from one energy state to another? True Spectral lines observed in the granules seen at the center of the S’s disk are blueshiped near the center of the granule and redshiped near the edge of the granul Spectral type, surface temp and color all describe the same basic characteris/c of star T Spectral types of stars uniquely define their surface temperatures Spectroscopy of a star can reveal its temperature, composi/on, and radial velocity T Spiral arms are regions of star forma/on, which accounts for their blue color T Star A and Star B both have an apparent magnitude of 2.0 but star A has an absolute magnitude of +3.0 and star B has an abs mag of -5.0 Star A and star b appear to have the same brightness but actually star B is brighter thanA Star A and star B both have an apparent magnitude of 4.0, but star A has an absolute magnitude of 1.0 and star B has an absolute magnitude of 7.0. Which statement below is correct? Star A and star B appear to have the same brightness, but actually star A is brighter than star B. Star A and Star B both have an apparent magnitude of 4.0 but star A has an absolute magnitude of 1.0 and star B has an abs mag of 7.0 Star A and star b appear to have the same brightness but actually star A is brighter than B Star A and star B have the same apparent magnitude. Star A is three /mes as distant as star B. Therefore, star A has three /mes the luminosity as star B. F Star A and star B have the same apparent magnitude. Star A is twice as distant as star B.Therefore, star A has twice the luminosity as star B. F Star A and Star B have the same temp but B is 20x smaller than A. Which statement.. Star A&B have the same color but star A is brighter Star A and star B have the same temperature, but different luminosi/es. What can you infer about these two stars? Nothing can be inferred from the informaLon given star A has a temperature 1/2 that of star B, but star A is 5 /mes bigger than star B. StarA is redder and brighter than star B Star A has a parallax of 0.02 arc/c. Star B has a parallax of 0.002 arcsec. How much further is star B from each than star A? 450 pc Star A is a main sequence star of spectral type A4 and star B is a white dwarf of spectral type A4. which statement is correct? Star A would be brighter if both stars were the same distance away Star A is a main sequence star of spectral type F2 and star B is a white dwarf of spectral type B4. Which is correct? Star B is hoTer than star A Star A is a main sequence star of spectral type G5 and star B is a red giant of spectral type K2. Star A is hoTer than star B Star A is iden/cal to Star B, except that Star A is twice as far from us as Star B. Therefore, both stars have the same luminosity, but the apparent brightness of Star B is four Lmes that of Star A. Stars with high masses live longer than stars with lower masses F Stellar Parallax is the apparent ship seen in the posiLon of a nearby star against more distant stars as we orbit the sun Sunspots appear dark because they are cooler than the surrounding surface Sunspots are cooler, darker regions on the Sun’s surface Sunspots are cooler than the surrounding region of the Sun’s surface T Sunspots are dark splotches on the Sun. Which statement is true? They are extremely hot, but cooler than the surrounding areas of the Sun. Sunspots come in pairs, represenLng the north and south magneLc fields. Suppose a comet orbits the Sun on a highly eccentric orbit where e = 0.2 and with an average semimajor axis distance of 140 AU. Determine the aphelion distance of this comet 112 AU Suppose a comet orbits the Sun on a highly eccentric orbit where e = 0.8 and with an average semimajor axis distance of 500 AU. Determine the aphelion distance of this comet 900 AU Suppose Earth’s axis had a greater /lt (more than 23.5 degrees). Which of the following statements would not be true? CelesLal sphere would be covered by a diff set of constellaLons Suppose Earth’s axis had a greater /lt (more than 23.5 degrees). Which of the following statements would not be true? The North celesLal pole would sLll be occupied by the star Polaris Suppose an object is moving in a straight line at 50mph. According to Newton’s first law of mo/on, the object will conLnue to move in the same way unLl it is acted upon by a force Suppose a photon has a f of 300 mill hertz, what is its wavelength? 1meter Suppose a white dwarf is gaining mass because of accre/on in a binary system. What happens if the mass someday reaches the 1.4-solar-mass limit? The white dwarf undergoes a catastrophic collapse, leading to a type of supernova that is somewhat different from that which occurs in a massive star but is comparable in energy. Suppose Earth’s axis had a greater /lt. Which would not be true? North celesLal pole would sLll be occupied by the star Polaris Suppose that a white dwarf is gaining mass through accre/on in a binary system. What happens if the mass someday reaches the 1.4 solar mass limit? The white dwarf will explode completely as a white dwarf supernova

Suppose that Hubble’s constant were 20 kilometers per second per million light-years. How fast would we expect a galaxy 100 million ly away to be moving? away from us Suppose the angular separa/on of two stars is smaller than the angular resolu/on of your eyes the two stars will look like a single point of light Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond…… They have the frequency of 2 hertz Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photo? Its wavelength and energy Suppose we imagine the S to be about the size of a grapefruit. How big an areas would the orbits of the eight size of Binghamton campus Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2, In this case we are seeing Galaxy 1 as it looked at an earlier Lme in the Suppose we observe a cepheid variable in a distant galaxy. The Cepheid brightens and dims with a regular period of 30 days 50000pc The absolute magnitude of a star is its brightness as seen from a distance of: ten parsecs The age of a star cluster can be determined by the luminosity of the main sequence turnoff into the giant stage T The age of a star cluster can be determined by the luminosity of the main sequence turnoff point T The age of the Universe is: Between 10 Billion and 16 Billion Years The amount of diffrac/on a telescope creates depends upon: the wavelength of light collected and the diameter of the telescope objecLve The amount of /me between successive passes of any given star across the meridian is 23 hours 56 minutes The angular resolu/on of a telescope is never less than its diffrac/on T The angular resolu/on of an 8 inch diameter telescope is ________ greater than that of a 2-inch diameter telescope. 4× The angular separa/on of 2 stars is 0.1 arcsec and you photograph them with a telescope the photo will seem to show only one star rather The Arecibo Radio telescope in Puerto Rico 305, 0.03-1.0, 0.5 LCA=73,000 D.L = 410 The axes on a HR diagram typical represent luminosity and surface temperature The brightest stars in a young open cluster will be massive blue stars at the top lep on the H-R diagram The brightest stars of a young open cluster will be Cepheid variables The celes/al coordinates of the Sun change from day to day T The Corona of the Sun is superheated and radiates Xrays with a peak wavelength of 0.2. Determine the temperature of this region of the Corona 15 x 10^6 K The cover sheet has a light curve for a Cephied Variable star. Determine the distance to the star. over 1,000 pc The cover sheet has a light curve for a typical RR Lyrae Variable star.Determine the period of /me for one complete cycle of change in brightness. Appox. how many cycles in brightness does this star go through in a week? 13-14 The diagram shows a binary star system. m2 is twice as far from the center than m1. If the period of revolu/on for the system is 10 years and the average sepera/on of the stars is 12AU, determine the mass of each star. m2 = 5.76 Solar Masses and m1 = 11.52 Solar Masses The diagram shows a binary stream where the mass of the smaller star is 8 solar masses. If the ra/o of seeds if 4:1…..if the larger star is 20 AU….. 158 years The diagram shows the believed structure of a black hole if viewed from the top and in 3D. Mass of the Sun is 2x10^30kg. 74km The densely packed neutrons of a neutron star cannot balance the inward pull of gravity if the total mass is greater than Schwartzschild's limit of 3 solar masses The diagram shows the light curve for 2 different Cephied variable stars. The longer period star is intrinsically brighter by approx. what factor? 1.7 Lmes brighter The diagram shows the light curve for Delta Cephei, the first variable star to be discovered. 10^3 Lsun The diagram shows the rota/on curve for 4 galaxies. Consider 2 civiliza/ons, one in NGC 4378 and other in NGC 1620. If each is at 10 kpc determine ra/o. 2.25 The diagram shows the rota/on curve for several galaxies. The visible por/on of NGC 4984 is about 24,000 parsec in radius. Es/mate the amount of mass contained in the visible por/on of NGC 4984. 6.8 x 1011 Msun The diagram shows the rota/on curve for the Milky Way. 1 km/s = 1000 m/s. The diagram shows the rota/on curve for the Milky Way. Determine the es/mated mass of the galaxy contained within the Sun’s orbital radius. 1x10^11 Msun The diagram shows the structure of the Milky Way and the Sun's loca/on in the disk. distance the sun travels in 1 orbit is the circumference of the circular orbit, and that velocity equals distance//me, determine the /me for 1 orbit of the Sun as it orbits the central black hole 8 x 10^15 sec. The discovery of the cosmic microwave background was important because it was experimental verificaLon of a predicLon from the Big Bang theory The Doppler Effect is a phenomenon that allows one to measure an object’s radial moLon The Doppler shib of the dark regions is 0.001% the speed of light. If one par/cular spectral line has the rest wavelength of 480.00 nm 480.48 The Earth lies close to the center of the Galaxy. F The Earth lies close to the center of the Milky Way Galaxy. F The eccentricity of a perfectly circular orbit is 0.5 F The energy levels for electrons vary form one element to another T The energy of the Sun starts as radia/on, but is actually transported to its surface by convec/on. where it is radiated off into space at last T The energy transfer process that operates in the S via mass mo/on is known convecLon The escape speed for a black hole's event horizon is the speed of light. T The fact that the Voyager spacecrab con/nues to speed out of the solar system, even though its rockets have no fuel, is an example of Newton's first law of moLon (law of inerLa). The faintest star visible to the naked eye has an apparent visual magnitude of about 6 The following diagram shows how the Cephied varaible HR 3343 varies in brightness. the avg app mag of HR3343 is m = 17.5, determine the d to the star 400,000pc The following diagram shows how the Cephied varaible HR 3343 varies in brightness. the period of /me for one complete cycle of change in brightness. 32 days The following diagram shows how a Cephied varaible varies in brightness. Determine the approximate average apparent magnitude 13.9 The following diagram shows how a Cephied variable varies in brightness. Determine the period of /me for one complete cycle of change in brightness. 5 days The following expressions are parameter of stars that astronomers obtained from their measurements. Which of these conclusions is not correct, based on the posi/ons of these stars luminosity=LS, radius = 1/10Rs, temp 20,000K The following light curve is for a variable star. Determine the distance to the star is the average apparent magnitude is m = 3.75. 224 pc The force of gravity varies with the product of the two masses, and inverse square of the distances separaLng the two bodies. The frequency of a wave is all of the above The Full Moon rises at sunrise, and sets at sunset. T The granular appearance of the surface of the S is evidence of what phenomenon convecLve moLon under the solar surface the graph shows the absorp/on spectrum of the star Vega and the Sun . The boVom graph. 4 Balmer absorp/on lines for Hydrogen Vega has hydrogen just like the Sun, and is hoTer than the Sun The Hertzsprung-Russell Diagram plots luminosity (or absolute magnitude) against the spectral type/temp The Hubble constant divided into the number one gives a rough es/mate for the age of the universe, or the "Hubble Time.” T The human eye has an average pupil diameter of 0.008m and can be considered a simple telescope. Mr. Taylor has placed 2 green dots (500nm wavelength) on the board in LH1. Johnny Student is si±ng 20m from the board in the lecture hall and the dots are 0.001m apart. Can Johnny resolve the dots? no The image shows the star Wolf 359, which has a large proper 0.4, 2.409 pc 4.56km/s The large reﬂector, 10m Keck, gathers more light than the 1m Yerkes refractor. If they both are using a 400nm violet filter, how does diff limit of 10km compare to 1m? 10 Lmes beTer The larger the value of Hubble's constant, the more rapid the expansion of the T The largest effec/ve telescope created by radio interferometry is size Earth The light gathering ability of a telescope is most dependent on the diameter of it's primary objec/ve. T The light radiated from the Sun's surface reaches Earth in about 8 minutes, but the energy of that light was released by fusion in the solar core about a million years ago The luminosity of a star is its total energy output per second The luminosity of the Sun is a measure of the total energy emiTed by the Sun in all direcLons The majority of the mass of the Milky Way lies farther out the Sun’s orbit T The Milky Way is simply our edge-on view of our home Galaxy. T The Moon is constantly falling toward Earth. T The most energe/c photons are gamma rays The most massive stars generate energy at the end of their lives by fusing F The Orion-Nebula, M-42 is a hot, thin cloud of glowing gas so its spectrum is a few bright lines against a dark background (emission spectrum) The overall fusion reac/on by which the Sun currently produces energy is 4 H ⇒ 1 He + energy The overall result of the proton-proton chain is 4H becomes 1He+ energy The parallax shib of a star would be greater if viewed from Mars than from Earth. Hint: Earth is the 3rd planet from the Sun and Mars is the 4th. T The paVern of rising hot gas cells all over the photosphere is called granulaLon The period-luminosity rela/on is cri/cal in finding distances with Cepheid variables

The photosphere of the S is about 100x the diameter of the E and large sunspots can be T The place in a planet's orbit that is closest to the Sun is called perihelion The primary purpose of an astronomical telescope is to magnify the images of distant objects, making them appear closer. F The primary purpose of a telescope is to collect a large amount of light and bring it into focus The primary source of the Sun's energy is the strong force fusing hydrogen into helium The process occurring when photons bounce off a polished surface is called reﬂecLon The proper mo/on of a star is its true velocity through space. F The proton-proton chain converts four hydrogen nuclei into one helium nucleus : True There are no limits to the mass with which a star can be born F There are no X-ray telescopes on Earth because X-rays don't penetrate Earth's atmosphere The red hydrogen line carries more energy per photon than the bluegreen hydrogen line does F Therefore, star A has twice the luminosity as star B. F The region on the H-R diagram where pulsa/ng variables occur is called instability strip There is no gravity in space F The rest wavelength of the Balmer blue/green line for Hydrogen has a wavelength of 486 nm, recessional velocity that is 15% the speed of light, shib? 73nm … (rest wavelength 559) Thermonuclear fusion reac/ons in the core of the S convert 4 hydrogen less mass than the 4 hydrogen atoms; the mass loss is converted to energy via equaLon The rota/on curve for our Galaxy shows stars furthest from the center are moving much faster than the Sun in their orbits. F The rota/on curve of the Milky Way suggests that the majority of the mass of the Milky Way lies farther out than the Sun's orbit T The ora/on of the sun’s photosphere is faster at the equator, slower at mid-laLtudes, and slowest near the poles The schwarzschild radius for a 12 solar mass star is 36km The seasons on Earth are caused by its ellip/cal orbit around the Sun F The S has an absolute magnitude of M=+4.8. How far away would we have to be for the sun to be just barely visible to the unaided eye. (i.e.if m=6) 17.4pc The S has apparent brightness B at the earth, which is 1.5x10^8 km away. What would be the apparent brightness of the sun at Pluto, which is 6.0x10^9 km from the sun? 0.00063 B The shorter a wave's wavelength, the greater it's energy. T the shorter its peak wavelength. F The shorter the wavelength of light, the higher its frequency T The solar corona is much cooler than the S’s surface, hence we must wait for a solar ecl F The spectral class of the star Enif is K2,while that of the S is G2, Enif is cooler than theS The spectral sequence in order of decreasing temp is OBAFGKM The speed of light is 3.00 × 108 m/s. If 2.00 kg of mass is converted to energy, how much energy will be produced? 1.80 × 1017 J The star Capella has an apparent magnitude of 0.08 and is at a distance of 13.16 parsec. Determine the absolute magnitude of Capella. -0.52 The star Hadar is classified as B1 II which means that it is a hot, bright giant The star named Circini has the spectral type and luminosity class of O 8.5 V. Based on this informa/on, which of the following are true? Circling has a diameter that is greater than that of the Sun, Circini is more luminous than the Sun, and Circini is located near the upper lep hand corner of the HR diagram The star shown is Rigel from the constella/on Oroin, 1AU, -38, +0.2, 772.9 -6.7 The star Vega has an absolute magnitude of about 4 and an apparent magnitude of about 0. Based on the defini/ons of absolute and apparent magnitude, we can conclude that - Vega is nearer than 10 parsecs from Earth. The Stefan-Boltzmann law indicates that the energy emiVed, 4000k, 6000K 20% The Sun is located at the edge of the galaxy, approximately 50,000 light-years from the galac/c center. F The Sun's average surface (photosphere) temperature is about. 5,800 K . The Sun’s magne/c field extends throughout the solar system T The Sun’s surface as we see it with our eyes is called the photosphere The sun's surface seethes and churns with a bubbling paVern. Why? We are seeing hot gas rising and cool gas falling due to the convecLon that occurs beneath the surface. The S’s luminosity is 3.83x10^26 waVs. By the /me this energy reaches E, it has spread out so that it provides only 1370 waVs, 1.53AU 585 The temperature of the corona of the Sun is very hot, about 10^6K The temperature of the layer of gas that produces the visible light radia/ng from the Sun's is 5800k The top row is the rest wavelength and the boVom row shows a doppler shib. rest wavelength=4800angstroms shibedwavelength=4920angstroms 7500km/sec The two forms of electromagne/c radia/on that penetrate the atmosphere best are visible&radio The typical speed of specular material traveling outward from the photosphere in the direc/on of Earth is 20km/s, 656nm 655.956nm The United States consumer 2.5x10^19 J of energy each year. The typical solar ﬂare releases 5.0x10^24…. Oxygen produced by life was removed from the atmosphere by oxidaLon reacLons with surface rocks The upper limit to the mass of a white dwarf is 1.4 solar masses T The vibra/ons of the Sun reveal informa/on about the interior structure of the sun. The visible color of electromagne/c radia/on that has the longest wavelength is red The visible color of electromagne/c radia/on that has the shortest wavelength is violet The wavelength of a wave is the distance between two adjacent peaks of the wave The “helium ﬂash” occurs at what stage in stellar evolu/on? red giant to calculate the combined masses of stars in a binary system, we must measure orbital period and average orbital distance The 26,000 year cycle that changes the poles and equinoxes is called precession To see the Sun’s hot outer layer at a temp of 1,000,000 K which part of the the X-ray Two important proper/es of young neutron stars are extremely rapid rotaLon and a strong magneLc field Two stars are equally distant from Earth. If the proper mo/on of star is A is 3x the proper mo/on of star B, but they both exhibit the same radial velocity, then which of the following is true? The space velocity of A is greater than that of B Two stars both lie on the main sequence. Star X is spectral type A, while Star Y is spectral type G. Therefore, Star X is more massive than Star Y. T Two stars have the same luminosity. Star X is spectral type F while Star Y is K .Star X F Two stars have the same spectral type. Star X is in luminosity class III, while T Two stars in a binary system have a combined mass of 12 solar masses. If 1 star is 5x further from the center of mass than the other, what are the 10&2 Two stars in our sky have the same app brightness. If neither of them is hidden behind gas or dust clouds may be at different distances, in which case the farther one must have the greater luminosity. Tycho Brahe's contribu/on to Kepler's Laws of Planetary Mo/on were his detailed and accurate observaLons of the planet’s posiLon Using an orbit size of 8 kpc, and a period of 225 million years…… 10^11 solar masses Using the HR diagram on the cover sheet, determine which of the following sequence in order of increasing size, stellar radius Sirius B, the sun, Mira, Betelgeuse varia/ons in its temperature from one place to another (corresponding to a few millionths of a degree Kelvin). T Vega is a main sequence star that has a luminosity 10 Lsun. Knowing this, which if the following statements is false?- Vega must be much larger than thee sun in diameter. Visible maVer belonging to the milky way galaxy can be traced out to about 50000 light years from the center 2x10^11Msun waves) of the same size have the same angular resolu/on. F Wein's law relates the peak wavelength of the blackbody to its size. The larger the black body, the shorter its peak wavelength. F We know the Sun rotates differen/ally by observing sunspots; as with Jupiter the solar equator rotates the fastest T We know the sun rotstes differen/ally by observing sunspots and like Jupiter the solar equator rotates the fastest. T What are constella/ons? Groups of stars making an apparent paTern in the celesLal sphere What are the characteris/cs of an open cluster of stars? A few Hundred, mainly Blue main sequence stars. What causes the apparent retrograde mo/on of the planets? As Earth passes another planet, the other planet appears to move backward with respect to the background stars, but the planet's moLon does not really change. What causes the apparent retrograde mo/on of the planets? As E passes another planet, the other planet appears to move backwards with respect to the background stars, but the planet’s moLon does not really change. What characteris/c of a star cluster is used to determine its age? the main sequence turnoff What contribu/on to astronomy was made by Tycho Brahe? His observaLons of planetary with great accuracy paved the way to discover the true moLon of the planets around the sun What do astronomers mean by light pollu/on light polluLon refers to light used for human acLviLes that brightens the sky and hinders What do astronomers mean when they say that we are all "star stuff”? C, O, & many elements essenLal to life were created by nucleosynthesis in stellar cores

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what does the hubble law imply about the history of the universe? The universe had a beginning and has expanded since, giving its finite age. What do sunspots, solar prominences, and solar ﬂares all in common? inﬂuenced by magneLc fields on the Sun What happens aber a helium ﬂash? The core quickly heats up and expands What happens when an interstellar cloud fragment shrinks? All of the above What informa/on about an astronomical object can be determined by observing its spectrum temp, chemical composiLon, radial moLon What inevitably forces a star like the sun to evolve away from being a main sequence star? helium builds up in the core, while the hydrogen burning shell expands What is a characteris/c of a main sequence star? The rate of nuclear energy generated in the hydrogen to helium fusion core equals the rate radiated from the surface What is a circumpolar star? a star that always remains above your horizon What is a planetary nebula? the ejected envelope, open bipolar, of a red giant surrounding a stellar core remnant What is a standard candle? an object for which we are likely to know the true luminosity What is an Astronomical Unit? The average distance from the earth to the sun What is the average length of /me from one maximum in the # of sunspots on the S, 11yr What is the basic defini/on of a black hole? any object from which the escape velocity exceeds the speed of light What is the name of the path between the points labeled 11 and 12? Planetary nebula What is characteris/c of a main sequence star? The rate of nuclear energy generated in the hydrogen to helium fusing core equals the rate radiated from the surface What is the CNO cycle? ype of hydrogen fusion that uses carbon, nitrogen, and oxygen atoms as catalysts What is the Eclip/c? The Sun’s apparent path along the celesLal sphere What is the light-gathering power of 8in telescope compared to 4in? 4x beTer What is the light gathering power of an 20in telescope compared to 10in telescope 4x What is the Luminosity of our Sun given a surface temperature of 5,800K and a diameter of What is the major difference between an ellip/cal galaxy and a spiral galaxy? An ellipLcal galaxy lacks a disk component What is the Schwarzschild radius of a 100 million-solar-mass blackhole? 300 milionkm What is the single most important characteris/c in determining the course of a star's evolu/on? mass What is the solar wind? A stream of charged parLcles ﬂowing outward from the surfa What is the temp of the universe as a whole today if the avg wavelength of the cosmic microwave background radia/on has been redshibed to 9.7x10^-4m? 3K What is the total mass of a binary star system with P = 20 yr and a = 10 AU? 2.5 solar masses What is the typical age for a globular cluster associated with our Milky Way? 10-12 billion years What is the typical age for a globular cluster associated with our milky way 10-12billion What is the typical main sequence life/me of a A-type star having a mass of 10 Solar Masses? ten million years … (2.15 solar masses= one billion years) What is the typical main sequence life/me of a B-type star if its mass is 50 solar masses? 20 million years What is the typical main sequence life/me of a M-type star having a mass of 0.21 Solar Masses? a trillion years What is the typical main sequence life/me of an O spectral type star having a mass of 18 Solar Masses? a couple million years What kind of object do we think lies in the center of the milky way galaxy? a 3- to- 4 million solar mass black hole What kinds of objects lie in the disk of our galaxy? gas and dust, open clusters, O and B stars What makes white-dwarf supernovae good standard candles? They are very bright, so they can be used to determine the distances to galaxies billions of light-years away, should all have approximately the same luminosity What physical property of a star does the spectral type measure? temperature What physical property of a star does the spectral type measure in the current arrangement of OBAFGKM? temperature What problem does adap/ve op/cs correct? turbulence in the earth's atmosphere which creates twinkling What problem does adap/ve op/cs correct? Turbulence What problem does reﬂec/ng telescope adap/ve op/cs correct? Turbulence in the Earth’s atmosphere which creates twinkling What term is given to the visible “surface” of the Sun? photosphere What two physical processes balance each other to create the condi/on known as gravita’onal equilibrium in stars? the inward pull of gravity and outward pressure what would happen if mass is added to a 1.4 solar mass white dwarf? the star would erupt as a carbon detonaLon (type I) supernova When 2 stars of unequal mass orbit each other under their mutual gravita/onal aVrac/on, where is the center of mass of the system located? point between the two stars, closer to the more massive star When a photon is produced in the core of the S, it undergoes a random photon walk that could last hundreds of thousands of years. During this process the photons F When does a protostar become a true star? When Nuclear Fusion begins in the core When white light passes through a cool cloud of gas we c an absorpLon line spectrum Where do we find our star on the H-R diagram In the middle of the main sequence Where in the Sun do fusion reac/ons happen? Only the core Where on Earth would you be if Polaris was on your horizon? Equator Where on Earth would you be if Polaris was your zenith? North pole Where on the HR diagram do most local stars in our universe congregate main sequence, where stars are generaLng energy by fusion reacLons Which 2 fundamental parameters are most oben used to place a par/cular star on a HR diagram luminosity and temperature Which event marks the birth of a star as it falls onto the main sequence? fusion of hydrogen atoms into helium atoms Which is the correct descrip/on of the sun’s loca/on within the milky way? in the disc and about one-half a galacLc radius from the center Which is the net result of the proton-proton chain? 4 protons = 1 helium 4 + 2 neutrinos + gamma rays Which layer of the sun do we normally see? photosphere Which of the choices below correctly lists things in order from largest to smallest? Universe, Local Group, Milky Way, Solar System Which of the following best describes the evolu/onary track followed on the H-R diagram for the most massive stars? horizontally right, diagonally to lower lep, then horizontally right Which of the following best explains why a solar day is longer than a sidereal day? Because earth orbits the sun at the same Lme it rotates, Earth must make slightly more then one full rotaLon. Which of the following best explains why nuclear fusion requires bringing nuclei extremely close together? Nuclei normally repel because they are all posiLvely charged and can be made to sLck only when brought close enough for the strong force to take hold. Which of the following correctly states the rela/onship between the apparent brightness, luminosity and distance of a star? App brightness = luminosity/4pi xdist^2 Which of the following can actually escape from inside a black hole's event horizon? none of the above Which of the following correctly describes the meridian in your sky ?a half-circle extending from your horizon due north, through your zenith, to your horizon due south Which of the following is largest? size of a typical galaxy Which of the following is most like the rota/on of stars in the disk of the Milky Way? cars moving at a constant speed on a circular race track Which of the following is not a characteris/c of the 11yr sunspot cycle the sunspot cycle is very steady so that each 11yr cycle is idenLcal to every other 11yr Which of the following is not a phase of the moon? Half Moon Which of the following is not a reason why telescopes tend to be built on mountaintops that are rela/vely the thin air on mountaintops Which of the following is not one of, nor follows directly from, Kepler's laws? The force of aTracLon between any two objects decreases with the square of the distance between their centers. Which of the following is the best answer to the ques/on, “why does the sun shine?” As the Sun was forming, gravitaLonal contracLon increased the Sun’s temp unLl the core becomes hot enough for nuclear fusion, which ever since has Which of the following is the most common type of star? low mass main sequence Which of the following is the reason for the solar day being longer than a sidereal day? the combined effect of the rotaLon of Earth and its orbit about the Sun Which of the following lists the stages of life for a low-mass star in the correct order? protostar, main sequence star, red giant, planetary nebula, white dwarf Which of the following luminosity classes refers to stars on the Main Sequence? V(5) Which of the following observa/ons is not a piece of evidence suppor/ng the big bang theory? RelaLve moLons of galaxies in the Local Group Which of the following quan//es is equal to the energy per sec generated by the S’s nuclear reac/ons? The luminosity of the Sun’s photosphere Which of the following sequences correctly describes the stages of life for a low-mass star? protostar, main-sequence, red giant, white dwarf Which of the following solar phenomena is not directly associated with the ac/ve Sun but is rather constant all the /me? GranulaLon Which of the following statements about apparent and absolute magnitude is T? all of the above ( the abs mag of a star= another measure of lum), 10parsecs, 2 Which of the following statements about sidereal and solar days is not true? A sidereal day is the definiLon of a day on the Earth and a solar day is the definiLon of a day

Which of the following statements about spectral types of stars is true? All of the above are true Which of the following statements about the celes/al equator is true at all la/tudes? It represents an extension of Earth’s equator onto the celesLal sphere Which of the following statements about the celes/al sphere is not true? The “ CelesLal Sphere” is just another name for our universe Which of the following statements about X-rays and radio waves is not true? X-rays travel through space faster than radio waves? Which of the following statements best describes the two principal advantages of telescopes over eyes? Telescopes can collect far more light with far beTer angular Which of the following statements does not use the term light-year in an appropriate way It will take me light-years to complete this homework assignment Which of the following stellar proper/es has the greatest range in values? Luminosity Which of the following terms is given to a pair of stars that we can determine are orbi/ng each other only by measuring their periodic Doppler shibs? spectroscopic binary Which of the following type electromagne/c radia/on lowest energy radio Which of the following types of galaxies are most spherical in shape? ellipLcals Which of these are not associated with the magne/cally ac/ve Sun? granulaLon Which of these does not exist? a 6.8 solar mass neutron star Which of these is constant for all types of electromagne/c radia/on in a vacuum? velocity Which of these is constant for ALL types of electromagne/c radia/on in a vacuum? velocity Which of these stars lie closest to the north celes/al pole on the celes/al sphere? Deneb Which of these was NOT a part of the original Copernican geocentric model? Mercury speeds up at perihelion, and slows down at aphelion. Which one explains the reason why there is not a solar eclipse at every new Moon The orbital plane of the Moon is Llted by about 5° to the eclipLc plane Which statement about stellar mo/on is incorrect? Like parallax, proper moLon is measured over intervals of exactly six months Which statement about the first quarter moon is FALSE? From the Earth it appears 25% sunlit Which statement about the length of a day is FALSE? The sidereal day includes both the Earth's rotaLon and revoluLon around the Sun. Which was a contribu/on to astronomy made by Copernicus? He laid out the order and relaLve moLon of the known solar system. While examining the spectrum of a galaxy you find all the hydrogen lines are shibed to longer wavelengths. This galaxy is moving away from us While more massive than most of its neighbors, the Sun is s/ll technically considered a low mass star. T While watching a star, you see it moves 45 degrees across the sky 3 hours White dwarfs and neutrons stars are all kept from collapsing by degeneracy T White dwarfs are so called because they are both very hot and very small. Why couldn't you stand on the Sun's surface? The Sun doesn't have a solid surface. Why does the star Bellatrix in Orion look bluish the spectrum of light emiTed from Bellatrix peaks in the ultraviolet region of the spectrum. Within the Why do sunspots appear dark in pictures of the Sun? They actually are fairly bright, but appear dark against the even brighter background of the surrounding photosphere. Why do we have seasons on Earth? As Earth goes around the Sun and Earth's axis remains pointed toward Polaris, the Northern and Southern hemispheres alternately receive more and less direct sunlight. Why do we see essen/ally the same face of the moon at all /mes? Because the Moon’s rotaLonal and orbital periods are equal Why is there a two day difference in the sidereal and synodic months? The Earth is also revolving around the Sun, so the Moon must “catch up” Why is the solar corona so much hoVer than the photosphere energy is carried upward through the chromosphere by disturbed and tangled magneLc fields X-rays, because they have more energy, travel through space faster than v F X-rays from astronomical objects can only be detected from telescopes in s T You are currently emi±ng electromagne/c waves in the infrared region of T You could more easily resolve a close double star with a blue telescope filter than with a red one T You note that a par/cular star is directly overhead. It will be directly 23hr56 You note that a par/cular star passes through your meridian. It will pass your meridian again in 23 hours 56 minutes ———— Ques/ons done ————————- Stars at different distances all appear to lie on the celesLal sphere . The EclipLc is the Sun's apparent path through the celes/al sphere. An object's alLtude (above horizon) and azimuth (direc/on along horizon) specify its loca/on in your local sky Meridian is the line passing through zenith (point directly overhead) and connec/ng the N and S points on Horizon Right Ascension - longitude. DeclinaLo n la/tude. Sun's declina/on is nega/ve in fall and winter and posi/ve in spring and summer. Stars rise and set because of Earths Rota/on. The /me of year determines the loca/on of the Sun on the celes/al sphere so that determines what constella/ons we see. Tilt of Earth’s Axis causes the seasons Sidereal day: Earth rotates once on its axis in 23 hours, 56 minutes, and 4.07 seconds. Solar day: The Sun makes one circuit around the sky in 24 hours. Sidereal month: Moon orbits Earth in 27.3 days. Earth and Moon travel 30° around Sun during that /me Synodic month: A cycle of lunar phases; takes about 29.5 days, 1/12 longer than a sidereal month. Sidereal year: Time for Earth to complete one orbit of Sun Tropical year: Time for Earth to complete one cycle of seasons. Tropical year is about 20 minutes (1/26,000) shorter than a sidereal year because of precession. Half of Moon is illuminated by Sun and half is dark. We see a changing combina/on of the bright and dark faces as Moon orbits. Phases are due to different amounts of sunlit porLon being visible from Earth Moon is Ldally locked to Earth—its rotaLon rate is the same as the Lme it takes to make one revoluLon, so the same side of the Moon always faces Earth Synchronous rota/on: The Moon rotates exactly once with each orbit. That is why only one side is visible from Earth. Lunar eclipses can occur only at full moon . Lunar eclipses can be penumbral , parLal , or total Sun then Earth then moon Solar eclipses can occur only at new moon . Solar eclipses can be parLal, total, or annular . Sun then Moon then Earth Eclipses occur when Earth, Moon, and Sun form a straight line. Eclipses don’t occur every month because Earth’s and Moon’s orbits are not in the same plane Moon has large dark ﬂat areas, due to lava ﬂow, called maria. Moon has craters too from meteorite impacts. Regolith: Thick layer of dust leb by meteorite impacts Ptolmeic model explains retrograde mo/on by saying planets really go backwards. The Ptolemaic model had each planet move on a small circle whose center moves around Earth on a larger circle. Earth centered model Copernicus, Tycho, and Kepler proposed a sun centered model. The model was no more accurate than the Ptolemaic model in predic/ng planetary posi/ons, because it s/ll used perfect circles. Kepler first tried to match Tycho's observa/ons with circular orbits, but an 8-arcminute discrepancy led him eventually to ellipses. Kepler's 1st Law : The orbit of each planet around the Sun is an ellipse with the Sun at one focus. Second As a planet moves around its orbit, it sweeps out equal areas in equal /mes. This means that a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun. More distant planets orbit the Sun at slower average speeds, obeying the rela/onship p2 = a3 p is orbital period in years. a is average distance from sun in AU Galileo showed that objects will stay in mo/on unless a force acts to slow them down (Newton's first law of mo/on). Weightlessness is due to a constant state of free-fall. Mass = quan/ty of maVer – Weight = force ac/ng on mass– Objects are weightless in free-fall. Newtons 3 laws . 1 Object in mo/on stays in mo/on unless acted on by outside force. 2 F=ma. 3 For every force, there is always an equal and opposite reac/on force. Objects con/nue at constant velocity because of conserva/on if momentum Angular momentum = mass x velocity x radius This keeps planets orbi/ng the sun Angular momentum conserva/on also explains why objects rotate faster as they shrink in radius. 1. Every mass aVracts every other mass. 2. AVrac/on is directly propor/onal to the product of their masses. 3 AVrac/on is inversely propor/onal to the square of the distance between their centers. ( Law of gravitaLon) Determinants of strength of gravity – Directly propor/onal to the product of the masses (M × m) – Inversely propor/onal to the square of the separa/on Total orbital energy stays constant. Unless acted on by another force like fric/on, atmospheric drag or atmospheric encounter Change in total energy is needed to change orbit – Add enough energy (escape velocity) and object leaves. Light is a form of energy . Unit of energy is waVs. 1 waV= 1j/s Photon - par/cles of light. Light can act as a par/cle or wave (a paVern of mo/on that carry energy without carrying maVer along with it) A light wave is a vibra/on of electric and magne/c fields. ElectromagneLc waves: Oscilla/ng electric and magne/c fields. Changing electric field creates magne/c field, and vice versa.

electrons in an atom are restricted to par/cular energy levels. MaTer is made of atoms, which consist of a nucleus of protons and neutrons surrounded by a cloud of electrons. The energies of electrons in atoms correspond to par/cular energy levels. – Atoms gain and lose energy only in amounts corresponding to par/cular changes in energy levels. ConLnuous Spectrum : no interrup/ons Emission line Spectrum : Sharp spike. A thin low-density cloud of gas emits light only at specific wavelengths that depend on its composi/on and temperature, producing a spectrum with bright emission lines. AbsorpLon Line Spectrum : sharp dip. A cloud of gas between us and a light bulb can absorb light of specific wavelengths, leaving dark absorp/on lines in the spectrum. each atom has unique Chemical fingerprint. Infrared spectrum is complicated and contains thermal radia/on Nearly all larger or dense objects emit thermal radia/on. Thermal radia/on depends on temperature. HoVer objects emit more light and emit photons with a higher average energy. Doppler ship tells us the blue or redshib of an objects speed toward or away from us. If neg toward us if posi/ve away. RefracLon is the bending of light when it passes from one substance into another. Your eye uses it to focus light. Refrac/on can cause parallel light rays to converge to a focus. The focal plane is where light from different direc/ons comes into focus. Eyes use refrac/on to bend parallel light rays so that they form an image. The image is in focus if the focal plane is at the re/na. most important proper/es of telescopes- 1. Light-collecLng area: Telescopes with a larger collec/ng area can gather a greater amount of light in a shorter /me. 2. Angular resoluLon: Telescopes that are larger are capable of taking images with greater detail. Angular resoluLon is minimum angular separa/on that the telescope can dis/nguish. If the angular separa/on of 2 objects is > the angular resolu/on of a telescope, then the telescope can resolve the objects. The DiffracLon Limi t of a telescope is the angular resolu/on of a telescope if it were limited by ONLY interference of light waves. ReﬂecLng telescopes can have much greater diameters. They have use mirrors and are used by professionals. Have long diameters. 3 things astronomers do with telescopes. Imaging- only one color is observed at a /me, so several images are combined to make full color images. Astronomical detectors can record forms of light our eyes can’t see. Spectroscopy- separates the different wavelengths of light before they hit the detector. Time monitoring- A light curve represents a series of brightness measurements made over a period of /me. Best Place for astronomical observa/ons on ground - calm, dark, dry, high. Best place is on top of remote mountains. These spots minimize light pollu/on, atmospheric turbulence, and bad weather. Light polluLon - issue for astronomers observing sky. Turbulent air ﬂow in Earth's atmosphere distorts our view, causing stars to appear to twinkle. Atmospheric blurring is due to air movement. AdapLve opLcs: Track atmospheric changes with laser; adjust mirrors in real /me We put telescopes in space because forms of light other than radio and visible don’t pass through earth’s atmosphere. No turbulence in space. Interferometery is a technique for linking two or more telescopes so that they have the angular resolu/on of a single large one. gravitaLonal equilibrium . Weight of Upper Layers compress lower layers. In equilibrium, inward gravita/onal force must be balanced by outward pressure. Energy Balance- The rate at which energy radiates from the surface of the Sun must be the same as the rate at which it is released by fusion in the core. Sun Shines b/c the gravita/onal equilibrium keeps core hot and dense enough to release energy through nuclear fusion. High Temp and Speed enable nuclear fusion to happen in core. Sun releases energy by fusing 4 H nuclei into 1 He nucleus. The Proton-Proton chain is how hydrogen fuses into helium in the sun- IN 4 protons OUT 4He nucleus 2 gamma rays 2 positrons 2 neutrinos Random Photon Walk: Energy gradually leaks out of radia/on zone in form of randomly bouncing photons. GranulaLon of the sun- evidence of convec/on. ConvecLon brings energy to the surface. Bright blobs on photosphere show convec/on. Nuclear fusion occurs in sun b/c. The core's extreme temperature and density are just right for nuclear fusion of hydrogen to helium through the proton–proton chain . Prominence- Loops of bright gas oben connect sunspot pairs. Solar Flares- Magne/c ac/vity causes solar ﬂares that send bursts of X rays and charged par/cles into space. solar prominences - Magne/c ac/vity also causes solar prominences that erupt high above the Sun's surface. Extreme events ( solar ﬂares ) can significantly inﬂuence Earth’s magne/c field structure and cause northern lights ( aurora borealis ). The corona appears bright in X- ray photos in places where magne/c fields trap hot gas. Solar Cycle- Aber 11 years, North/South order of leading/trailing sun spots is reversed . Total Solar Cycle is 22 years. The Magnetosphere- region around the Earth where charged par/cles from the solar wind are trapped Van Allen Belts- these charged par/cles are trapped in areas called the Van Allen belts, where they spiral around magne/c field lines. Near the poles, the Van Allen Belts intersect the atmosphere. The charged par/cles can escape; when they do, they create glowing light called Aurorae. • Parallax is the apparent shib in posi/on of a nearby object against a background of more distant objects. Parallax angle depends on distance. Parallax is measured by comparing snapshots taken at different /mes and measuring the shib in angle to star. proper moLon is the actual shib of the star in the sky, aber correc/ng for parallax . The brightness of a star depends on both distance and luminosity. Absolute Magnitude (M) = Magnitude that a star would have if it were at a distance of 10 pc. Apparent Magnitude- brightness measured at actual distance from Earth Visual Binary Star System: the ideal case: Both stars can be seen directly, and their separaLon and relaLve moLon can be followed directly. Spectroscopic Binary Star Systems: Usually, binary separaLon a cannot be measured directly because the stars are too close to each other. We determine the orbit by measuring Doppler Ships. Spectroscopic binaries can be measured using their Doppler ships Red stars are cool, blue stars are hoTer. • Most stars fall somewhere on the main sequence of the H-R diagram. Stars with lower T and higher L than main-sequence stars must have larger radii. These stars are called giants and supergiants . Stars with higher T and lower L than main- sequence stars must have smaller radii. These stars are called white dwarfs . HR Diagram depicts: Temp, color, spectral type, luminosity, radius -Most stars fall somewhere on the main sequence of the H-R diagram. -Stars with lower T and higher L than main-sequence stars must have larger radii. These stars are called giants and supergiants . -Stars with higher T and lower L than main- sequence stars must have smaller radii- white dwarf - Main-sequence stars are fusing hydrogen into helium in their cores like the Sun.- Mass measurements of main- sequence stars show that the hot, blue stars are much more massive than the cool, red ones.- Luminous main- sequence stars are hot (blue). -Less luminous ones are cooler (yellow or red). - Stars form in dark clouds of dusty gas in interstellar space. - The gas between the stars is called the interstellar medium. - We can determine the composi/on of interstellar gas from its absorp/on lines in the spectra of stars. Trapping of Thermal Energy - . - Contrac/on slows down, and the center of the cloud fragment becomes a protostar. MaVer from the cloud con/nues to fall onto the protostar un/l either the protostar or a neighboring star blows the surrounding gas away. Brown Dwarf- < 0.08MSun before core temperature becomes hot enough for fusion. - radia/on pressure limits how massive a star can be without blowing itself apart. (Maximum thought to be around 150MSun,) High-Mass Star: • High luminosity • Short-lived• Larger radius• Blue • Life expectancy of 0.1MSun star: Low-Mass Star : • Low luminosity • Long-lived• Small radius • Red The mass of a main-sequence star determines its core pressure and temperature. - Stars of higher mass have higher core temperature and more rapid fusion, making those stars both more luminous and shorter-lived. - Stars of lower mass have cooler cores and slower fusion rates, giving them smaller luminosi/es and longer life/mes. – Helium Flash - The thermostat of a low-mass red giant is broken because degeneracy pressure supports the core. - Core temperature rises rapidly when helium fusion begins. Double Shell Burning - Aber core helium fusion stops, helium fuses into carbon in a shell around the carbon core, and hydrogen fuses to helium in a shell around the helium layer. - This double shell–burning stage never reaches equilibrium—fusion rate periodically spikes upward in a series of thermal pulses. End of Fusion - Fusion progresses no further in a low-mass star because the core temperature never grows hot enough for fusion of heavier elements CNO cycle - High-mass main- sequence stars fuse H to He at a higher rate using carbon, nitrogen, and oxygen as catalysts -Greater core temperature enables hydrogen nuclei to overcome greater repulsion. MulLple Shell Burning- Iron is a dead end for fusion because nuclear reac/ons involving iron do not release energy. Supernova Explosions- Core degeneracy pressure goes away because electrons combine with protons making neutrons and neutrinos. Neutrons collapse to the center, forming a neutron star. Supernova Remnant- Energy released by the collapse of the core drives the star's outer layers into space. Crab nebula White Dwarfs- White dwarfs are the remaining cores of dead stars. A white dwarf that is part of a Semidetached binary system can undergo repeated novas.. 2 Types of Supernova: Massive star supernova- Iron core of a massive star reaches white dwarf limit and collapses into a neutron star, causing total explosion. White Dwarf Supernova- Carbon fusion suddenly begins as a white dwarf in close binary system reaches white dwarf limit, causing total explosion. -Supernovae: are MUCH MUCH more luminous. complete explosion of white dwarf, nothing leb behind -One way to tell supernova types apart is with a light curve showing how luminosity changes with /me. Supernovae- a one-/me event—once it happens, there is liVle or nothing leb of the progenitor star. two different types of supernovae: Type I, which is a carbon- detona/on supernova, Type II, which is the death of a high-mass star just described.

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Neutron Star: Aber a Type I supernova, liVle or nothing remains of the original star. - Aber a Type II supernova, part of the core may survive. MagneLc field —again as a result of the collapse, the neutron star’s magne/c field becomes enormously strong.- Pulsar is a neutron star that beams radia/on along a magne/c axis that is not aligned with the rota/on axis. Black Holes- an object whose gravity is so powerful that not even light can escape it. The mass of a neutron star cannot exceed about 3 solar masses. If a core remnant is more massive than that, nothing will stop its collapse, and it will become smaller and smaller and denser and denser. Eventually, the gravita/onal force is so intense that even light cannot escape. The remnant has become a black hole. No Escape- Nothing can escape from with in the event horizon because nothing can go faster than light. It’s a black hole if it’s not a star and its mass exceeds the neutron star limit (~3MSun) Globular cluster: Up to a million or more stars in a dense ball bound together by gravity. Open Cluster- A few thousand loosely packed stars -Knowing a star cluster's distance, we can determine the luminosity of each type of star within it. -The main- sequence turnoff point of a cluster tells us its age Variable Stars- Any star that varies significantly in brightness with /me is called a variable star. Cepheid Variable Stars – Excellent Standard Candles - Most pulsa/ng variable stars inhabit an instability strip on the H-R diagram. -The most luminous ones are known as Cepheid variables. Cepheid periods range from about 1 to 100 days. RR Lyrae stars all have about the same luminosity;; knowing their apparent magnitude allows us to calculate the distance. Period is .5 to 1 day. Standard Candles- Aber appropriate calibra/ons, the P-L Rela/on allows for a powerful distance measuring tool.– Variable Stars & the Instability Strip - The variability of these stars comes from a dynamic balance between gravity and pressure—they have large oscillaLons around stability. Hubble deep field - Our deepest images of the universe show a great variety of galaxies, some of them billions of light-years away. Galaxies and Cosmology- A galaxy's age, its distance, and the age of the universe are all closely related. -The study of galaxies is thus in/mately connected with cosmology— the study of the structure and evolu/on of the universe.

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