Mid Term-2 ASTR 1303 Fall 2022 bez otvetov case 102323 (FILLED)

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ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 1 ASTR 1303 Midterm 2 Fall 2022 Chapter 17 SecƟon 17.1 True or False 17.1.1) The nearest naked-eye star to our Sun, Alpha Centauri, is sƟll over a parsec distant. Answer: ____ True SecƟon Ref: 17.1 17.1.2) First magnitude Spica appears 2.5 Ɵmes brighter than second magnitude Polaris. Answer: _____ False SecƟon Ref: 17.2 17.1.3) If a star were moved 10 Ɵmes farther away, its apparent magnitude would drop by five magnitudes. Answer: _____ False SecƟon Ref: 17.2 17.1.4) A type B9 star is hoƩer than a type A0. Answer: _____ Fasle SecƟon Ref: 17.3 17.1.5) Hydrogen lines are weaker in both very hot and very cool stars. Answer: _____ True SecƟon Ref: 17.3 17.1.6) A star of the Sun's diameter, but twice as hot, must be 16X more luminous than the Sun. Answer: _____ False SecƟon Ref: 17.4 17.1.7) The vast majority of stars near us would fall to the boƩom right on the H-R diagram. Answer: _____ False SecƟon Ref: 17.5 17.1.8) The Sun's complete classificaƟon is G2V. Answer: _____ True SecƟon Ref: 17.6 17.1.9) In a spectroscopic binary, the star whose lines shiŌ the most weighs the most. Answer: _____ False SecƟon Ref: 17.7 17.1.10) Eclipsing binaries are the most useful, giving us sizes as well as masses of the pair. Answer: _____ True SecƟon Ref: 17.7 17.1.11) A star of ten solar masses would probably stay stable on the main sequence only about 1/1000th as long as our Sun. Answer: _____ True SecƟon Ref: 17.8 ======================================================== SecƟon 17.2 MulƟple Choice 17.2.1) A nearby star has a parallax of 0.2 arc seconds. What is its distance? A) .1 parsec B) .2 parsec C) .5 parsec D) 5 parsecs E) 50 parsecs Answer: _____ D SecƟon Ref: 17.1
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 2 17.2.2) If a star has a parallax of 0.05" ( “ = arcseconds), then its distance in light years (lys) is about: A) 6.4 lys. B) 12.7 lys. C) 20 lys. D) 65 lys. E) 100 lys. Answer: _____ D SecƟon Ref: 17.1 17.2.3) What is the absolute magnitude of our Sun? A) -23.0 B) -4.6 C) -1.4 D) +4.8 E) +9.4 Answer: _____ D SecƟon Ref: 17.2 17.2.4) The absolute magnitude of a star is its brightness as seen from a distance of: A) one million kilometers. B) one astronomical unit. C) one light year. D) ten parsecs. E) 10 light years. Answer: _____D SecƟon Ref: 17.2 17.2.5) What are the two most important intrinsic properƟes used to classify stars? A) mass and age B) luminosity and surface temperature C) distance and luminosity D) distance and surface temperature E) distance and color Answer: ___B__ 17.2.6) What physical property of a star does the spectral type measure? SecƟon Ref: 17.3 A) density B) luminosity C) temperature D) mass E) composiƟon Answer: __C___ 17.2.7) The star's color index is a quick way of determining its: SecƟon Ref: 17.3 A) density. B) luminosity. C) mass. D) temperature. E) composiƟon. Answer: _____ D SecƟon Ref: 17.3 17.2.8) Stars that have masses similar to the Sun's, and sizes similar to the Earth are: A) main sequence stars. B) white dwarfs. C) red giants. D) red dwarfs. E) brown dwarfs. Answer: _____ E SecƟon Ref: 17.4 17.2.9) Compared to the size of the Sun, in what range of sizes (solar radii) are nearly all stars found? A) .5 to 2 B) 0.1 to 1.0 C) 0.5 to 50 D) 1 to 100 E) 0.01 to 100 Answer: _____ A SecƟon Ref: 17.4 17.2.10) On the H-R diagram, the Sun lies: A) at the top leŌ. B) at the boƩom leŌ. C) at the boƩom right. D) about the middle of the main sequence. E) at the top right. Answer: _____ D SecƟon Ref: 17.5
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 3 17.2.11) Which of the following is the most common type of star? A) high mass main sequence B) low mass main sequence C) white dwarfs D) red giants E) blue supergiants Answer: _____ B SecƟon Ref: 17.5 17.2.12) How might the most common occurring stars be described, based on our stellar neighborhood? A) white dwarfs B) K giants C) G main sequence D) A main sequence E) M main sequence Answer: _____ E SecƟon Ref: 17.5 17.2.13) Which type of binary can have their sizes measured directly by photometry? A) virtual B) visual C) eclipsing D) spectroscopic E) astrometric Answer: _____ C SecƟon Ref: 17.7 17.2.14) What is the single most important characterisƟc in determining the course of a star's evoluƟon? A) density B) absolute brightness C) distance D) surface temperature E) mass Answer: ___E__ SecƟon Ref: 17.8 Select the leƩer for the appropriate lifeƟmes below: SecƟon Ref: 17.8 A) one million years B) 20 million years C) ) 100 million years D) one billion years E) ten billion years F) ) 100 billion years G) a trillion years 17.2.15) What is the typical main sequence lifeƟme of an M-type star? Answer: __G__ 17.2.16) What is the typical main sequence lifeƟme of a G-type star? Answer: __D___ 17.2.17) What is the typical main sequence lifeƟme of a B-type star? Answer: ___B__ 17.2.18) For a star of 10 solar masses, its main sequence lifeƟme relaƟve to our Sun will be: A) 10x longer. B) about the same. C) one tenth D) 100x less. E) only 1/1000th. Answer: _____ E SecƟon Ref: 17.8
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ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 4 Chapter 18 SecƟon 18.1 True or False 18.1.1) The "Local Bubble" was probably created by a nearby supernova in the distant past. Answer: _____ True SecƟon Ref: Discovery 18-1 18.1.2) The H I regions are mapped by the radiaƟon created when an electron flips its spin. Answer: _____ False SecƟon Ref: 18.4 18.1.3) The 21 cm line of hydrogen is strongly absorbed by interstellar dust. Answer: _____ False SecƟon Ref: 18.4 18.1.4) Dark dust clouds radiate mainly in the radio porƟon of the electromagneƟc spectrum. Answer: _____ False SecƟon Ref: 18.4 18.1.5) Most molecules found in the giant molecular clouds are based on silicon. Answer: _____ False SecƟon Ref: 18.5 ====================================== SecƟon 18.2 MulƟple Choice 18.2.1) Interstellar gas is composed of: A) only hydrogen. B) 90% hydrogen, 9% helium by weight. C) 10% hydrogen, 90% helium by numbers of atoms. D) some hydrogen, but mainly carbon dioxide. E) ammonia, methane, and water vapor. Answer: _____ B SecƟon Ref: 18.1 18.2.2) Due to absorpƟon of shorter wavelengths by interstellar dust clouds, distant stars appear: A) bluer. B) brighter. C) redder. D) larger. E) to have a higher radial velocity. Answer: _____ C SecƟon Ref: 18.1 18.2.3) Emission nebulae like M42 occur only near stars that emit large amounts of: A) visible light. B) microwaves. C) ultraviolet radiaƟon. D) infrared. E) X-rays & gamma rays. Answer: ____C_ SecƟon Ref: 18.2 18.2.4) A large gas cloud in the interstellar medium that contains several type O and B stars would appear to us as: A) a dark nebula. B) an emission nebula. C) bright blue. D) a reflecƟon nebula. E) a dark patch against a bright background. Answer: _____ B SecƟon Ref: 18.2 18.2.5) Which of these is NOT a consequence of dust in the interstellar medium? A) reddening of stars' light that passes through the dust B) blue reflecƟon nebulae around the Pleiades
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 5 C) red light from the emission nebulae D) the dark nebulae that block 90% of the Milky Way from us visually E) terrestrial planets like our own Answer: _____ E SecƟon Ref: 18.2 18.2.6) Astronomers use roman numerals to indicate the ionizaƟon state of a gas. Ionized hydrogen is indicated by which of the following symbols? A) H II B) H2 C) H I D) H 1 1 E) H III Answer: _____ A SecƟon Ref: 18.2 18.2.7) Charles Messier mapped the night sky and idenƟfied many objects now known to be emission nebulae in his search for objects that might be confused with: A) comets. B) asteroids. C) galaxies. D) dark nebulae. E) reflecƟon nebulae. Answer: _____ A SecƟon Ref: 18.2 18.2.8) Interstellar absorpƟon lines are narrow primarily because: A) there is very liƩle interstellar maƩer. B) molecules always produce narrow absorpƟon lines. C) most of the maƩer is ionized, and atoms moving fast produce sharp lines. D) the maƩer is at a low temperature, and atoms are almost sƟll. E) All of the above are correct. Answer: _____ D SecƟon Ref: 18. 3 18.2.9) What informaƟon does 21 cm radiaƟon provide about the gas clouds? A) their moƟon B) their distribuƟon C) their density D) their temperature E) all of these Answer: _____ A SecƟon Ref: 18.4 18.2.10) When an electron in H changes its spin from the same to opposite direcƟon as the proton, it: A) emits an X-ray photon. B) absorbs a radio wave photon. C) emits a radio wave photon. D) absorbs a visible light photon. E) neither emits nor absorbs a photon. Answer: _____ C SecƟon Ref: 18.4 18.2.11) The most common molecule in a molecular cloud is: A) methane, CH4. B) molecular hydrogen, H2. C) carbon monoxide, CO. D) water, H2O. E) ammonia, NH3. Answer: _____ B SecƟon Ref: 18.5
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 6 18.2.12) Complex molecules in space are found in: A) photospheres of red giant stars. B) dense dust clouds. C) coronas of stars like our Sun. D) scaƩered evenly throughout interstellar space. E) surrounding the more energeƟc young stars. Answer: _____ B SecƟon Ref: 18.5 18.2.13) Which of the following has NOT yet been observed in space? A) formaldehyde B) methyl alcohol C) DNA D) ammonia E) hydrogen cyanide Answer: _____ C SecƟon Ref: 18.5 18.2.14) Unlike atoms, molecules can: A) rotate. B) vibrate. C) spin. D) Both A and B. E) All of the above. Answer: _____ E SecƟon Ref: 18.5 ============================== Chapter 19 SecƟon - No 19.1 True or False SecƟon 19.2 MulƟple Choice QuesƟons 19.2.1) What makes the subject of star formaƟon so difficult and complex? A) It is so slow that no visible proof of it exists. B) Star formaƟon is too expensive to study in detail. C) Stars live too long to be observed from birth to death. D) Clouds, fragments, protostars, stars, and nebulae all interact and influence each other. E) Shock waves disrupt the orderly evoluƟon of stars. Answer: _____ D SecƟon Ref: 19.1 19.2.2) Our Sun, along with most of the stars in our neighborhood, probably formed: A) a few million years ago. B) about 10 million years ago. C) hundreds of millions of years ago. D) billions of years ago. E) at the beginning of the universe. Answer: _____ D SecƟon Ref: 19.1 19.2.3) What is the force that keeps a main sequence star from blowing apart? A) magneƟsm B) gravitaƟon C) strong force D) radiaƟon pressure E) electron degeneraƟon pressure Answer: _____ B SecƟon Ref: 19.1 19.2.4) Which event marks the birth of a star? A) formaƟon of the planetary nebula B) fusion of hydrogen atoms into helium atoms C) interstellar cloud collapse D) formaƟon of a photosphere E) interstellar cloud instability Answer: _____ C SecƟon Ref: 19.2
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ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 7 19.2.5) What happens when an interstellar cloud fragment shrinks? A) It first becomes opaque. B) Density rises. C) Temperature rises. D) Pressure rises. E) All of the above. Answer: _____ E SecƟon Ref: 19.2 19.2.6) During a protostar's T Tauri phase, it: A) begins a period of reduced acƟvity. B) expands dramaƟcally. C) lies on the main sequence. D) may develop very strong stellar winds. E) changes its spin direcƟon. Answer: _____ D SecƟon Ref: 19.2 19.2.7) A newly formed protostar will radiate primarily at which wavelength? A) visible light B) X-ray C) infrared D) ultraviolet E) radio Answer: _____ C SecƟon Ref: 19.2 19.2.8) How long does it take for a star like our Sun to form? A) 100 thousand years B) two million years C) fiŌy million years D) one billion years E) 4.6 billion years Answer: _____ B SecƟon Ref: 19.2 19.2.9) On an H-R diagram, a protostar would be: A) above and to the right of the main sequence. B) below and to the leŌ of the main sequence. C) below and near the right side of the main sequence. D) above and near the upper leŌ of the main sequence. E) on the main sequence at the extreme lower right. Answer: ___A__ SecƟon Ref: 19.2 19.2.10) A cloud fragment too small to form a star becomes: A) a red giant. B) a black hole. C) a brown dwarf. D) a T Tauri object. E) a Herbig Haro object. Answer: _____ C SecƟon Ref: 19.3 19.2.11) How long does it take an M class star to reach the main sequence, compared to a solar type star? A) 1/10th as long B) about the same, 30 million years C) about twice as long D) about twenty Ɵmes longer E) longer than the age of the Galaxy Answer: _____ D SecƟon Ref: 19.3 19.2.12) The stars found in nebulae like the Orion Nebula probably formed:
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 8 A) a few million years ago. B) about 10 million years ago. C) hundreds of millions of years ago. D) billions of years ago. E) at the beginning of the universe. Answer: _____ A SecƟon Ref: 19.4 19.2.13) One (short term) energy source for brown dwarfs is: A) hydrogen fusing to helium. B) helium fusing to carbon. C) iron core collapse. D) helium-3 fusing to helium-4. E) deuterium fusing to helium-3. Answer: _____ E SecƟon Ref: Discovery 19-1 19.2.14) Brown dwarfs are most easily detected which porƟon of the electromagneƟc spectrum? A) X-ray B) ultraviolet C) visible light D) infrared E) radio Answer: _____ D SecƟon Ref: Discovery 19-1 19.2.15) Why are star clusters almost ideal "laboratories" for stellar studies? A) All stars in the cluster are the same size and luminosity. B) Their combined light makes them much easier to spot from a distance. C) Stars in clusters have the same age, similar composiƟon, and are at the same distance away. D) Stars in clusters are all relaƟvely young and therefore shine brightly. E) Like our Sun, stars in clusters are always located in the plane of the Milky Way Galaxy. Answer: _____ C SecƟon Ref: 19.6 19.2.16) What are the characterisƟcs of globular cluster stars? A) no stars as hot as our Sun B) old age and hundreds of thousands to millions of member stars C) no main sequence stars leŌ, with billions of member stars D) a few hundred stars, most sƟll on the main sequence E) hundreds of light years across, with bright OB stars dominant Answer: _____ B SecƟon Ref: 19.6 ==================================================================== Chapter 20 SecƟon N0 20.1 True or False SecƟon 20.2 MulƟple Choice 20.2.1) A star (no maƩer what its mass) spends most of its life as a: A) proto-star. B) main sequence star. C) planetary nebula. D) red giant or supergiant. E) as a T Tauri variable star. Answer: _____ B SecƟon Ref: 20.1 20.2.2) When a star's inward gravity and outward pressure are balanced, the star is said to be: A) in gravitaƟonal collapse. B) in thermal expansion. C) in rotaƟonal equilibrium.
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 9 D) in hydrostaƟc equilibrium. E) a stage 2 protostar. Answer: _____ D SecƟon Ref: 20.1 20.2.3) What spectral type of star that is sƟll around formed longest ago? A) O B) A C) F D) K E) M Answer: _____ A SecƟon Ref: 20.1 20.2.4) What spectral type of star that is sƟll around formed most recently? A) O B) A C) F D) K E) M Answer: _____ E SecƟon Ref: 20.1 20.2.5) At which stage in a Sun-like star's life is its core the least dense? A) Main Sequence B) Subgiant Branch C) Helium Fusion D) Planetary Nebula E) White Dwarf Answer: _____ A SecƟon Ref: Table 20.1 20.2.6) Which of the following elements contained in your body is NOT formed in the cores of stars during thermonuclear fusion? A) hydrogen B) carbon C) calcium D) iron E) aluminum Answer: _____ C SecƟon Ref: 20.2 20.2.7) What temperature is needed to fuse helium into carbon? A) 5,800 K B) 100,000 K C) 15 million K D) 100 million K E) one billion K Answer: _____ C SecƟon Ref: 20.2 20.2.8) A star is on the horizontal branch of the H-R diagram. Which statement is true? A) It is burning both hydrogen and helium. B) It is about to experience the helium flash. C) It is burning only helium. D) The star is contracƟng. E) The star is about to return to the main sequence. Answer: _____ C SecƟon Ref: 20.2 20.2.9) What inevitably forces a star like the Sun to evolve away from being a main sequence star? A) The core begins fusing iron. B) The star uses up all its supply of hydrogen. C) The carbon detonaƟon explodes it as a type I supernova. D) Helium builds up in the core, while the hydrogen burning shell expands. E) The core loses all its neutrinos, so all fusion ceases. Answer: _____ B SecƟon Ref: 20.2
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ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 10 20.2.10) The brightest stars in aging globular clusters will be: A) core stars of planetary nebulae. B) massive blue main sequence stars like Spica. C) blue stragglers. D) red supergiants like Betelguese and Antares. E) blue supergiants like Rigel and Deneb. Answer: _____ C SecƟon Ref: 20.5 20.2.11) NoƟng the turnoff mass in a star cluster allows you to determine its: A) distance. B) radial velocity. C) age. D) total mass. E) number of stars. Answer: _____ C SecƟon Ref: 20.5 20.2.12) The most famous case of a more massive hot star orbiƟng with a more evolved but presently less massive red giant is the eclipsing binary: A) Aldeberan. B) Antares. C) Algol. D) Alberio. E) Altair. Answer: _____ C SecƟon Ref: 20.6 20.2.13) Mass transfer in binaries occurs when one giant swells to reach the: A) Chandrasekhar Limit. B) Cassini Division. C) Hayashi Track. D) Roche Lobe. E) Herbig-Haro Limit. Answer: _____ D SecƟon Ref: 20.6 Chapter 21 No SecƟon 21.1 True or False SecƟon 21.2 MulƟple Choice 21.2.1) A surface explosion on a white dwarf, caused by falling maƩer from the atmosphere of its binary companion, creates what kind of object? A) hypernova B) nova C) gamma ray burstar D) type I supernova E) type II supernova Answer: _____ B SecƟon Ref: 21.1 21.2.2) The Chandrasekhar mass limit in solar masses is: A) 0.08 B) 0.4 C) 1.4 D) 3 E) 8. Answer: _____ C SecƟon Ref: 21.1 21.2.3) For a nova to occur, the system must have already been in what kind of binary system? A) astrometric. B) detached. C) spectroscopic. D) mass-transfer. E) eclipsing binary. Answer: _____ D SecƟon Ref: 21.1 21.2.4) The total energy emiƩed by the brightest nova explosions is equivalent to how many suns? A) 1,000. B) 50,000. C) a million. D) a billion. E) a trillion.
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 11 Answer: _____ C SecƟon Ref: 21.1 21.2.5) Beyond the formaƟon of iron, nuclear energy can be produced only by: A) fusion of sƟll heavier elements. B) ionizaƟon of the radioacƟve nuclei. C) fission of heavy nuclei back toward lighter ones. `D) gravity. E) the dark force. Answer: _____ A SecƟon Ref: 21.2 SecƟon Ref: 21.2 21.2.6) When a stellar iron core collapses, large numbers of neutrinos are formed, and then they : A) form the neutron star. B) are absorbed by electrons to produce positrons. C) are captured to form heavy elements. D) are captured to form light elements. E) immediately pass through the core and escape to space. Answer: _____ E SecƟon Ref: 21.2 21.2.7) As a star's evoluƟon approaches the Type II supernova, we find: A) the heavier the element, the less Ɵme it takes to make it. B) the heavier the element, the higher the temperature to fuse it. C) helium to carbon fusion takes at least 100 million K to start. D) photodisintegraƟon of iron nuclei begins at 10 billion K to ignite the supernova. E) All of the above are correct. Answer: _____ E SecƟon Ref: 21.2 21.2.8) What made supernova 1987a so useful to study? A) We saw direct evidence of nickel to iron decay in its light curve. B) Its progenitor had been observed previously. C) In the Large Magellanic Cloud, we already knew its distance. D) It occurred aŌer new telescopes, such as Hubble, could observe it very closely. E) All of the above are correct. Answer: _____ B SecƟon Ref: 21.3 21.2.9) What evidence is there that supernovae really have occurred? A) Crab Nebula B) supernova remnants C) existence of heavy radioacƟve elements in nature D) observaƟons of the actual explosions E) All of the above. Answer: _____ A SecƟon Ref: 21.3 21.2.10) What produces a type-I supernova? A) the collapse of the core of a massive star B) the helium flash blows apart a giant's core C) mass transfer onto a white dwarf pushing it over 1.4 solar masses
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 12 D) a nova igniƟng a helium flash in its red giant companion E) the radioacƟve decay of nickel 56 into cobalt 56 into iron 56 Answer: _____ C SecƟon Ref: 21.3 21.2.11) For a white dwarf to explode enƟrely as a Type I supernova, its mass ( in solar units) must be: A) at least 0.08. B) 1.4, the Chandrasekhar Limit. C) 3, the Schwartzschild Limit. D) 20, the Hubble Limit. E) 100, the most massive known stars. Answer: _____ B SecƟon Ref: 21.3 21.2.12) Nearly all the elements found in nature were formed inside stars, EXCEPT for: A) carbon and silicon. B) hydrogen and helium. C) helium and carbon. D) silver and techneƟum. E) uranium and radium. Answer: _____ B SecƟon Ref: 21.4 21.2.13) What direct evidence do astronomers have that supports the heavy element formaƟon in stars? A) the presence of techneƟum in giant star spectra B) observed elemental abundances C) gamma-ray emissions from decay of cobalt 56 in supernovae D) light curves of type-I supernovae E) All of the above are evidence of this. Answer: _____ A SecƟon Ref: 21.4 21.2.14) Which statement about young stars is FALSE? A) They contain a larger fracƟon of heavy elements than previous generaƟons. B) They are born in a dusƟer environment than earlier generaƟons. C) They are more likely to have planets forming with them than earlier generaƟons. D) The high mass stars will be more likely to produce heavier elements as they evolve. E) Being young, they will have more pure hydrogen than earlier generaƟons. Answer: _____ D SecƟon Ref: 21.5 21.2.15) Type II supernovae and star forming regions are related to one another because: A) they both contain ionized hydrogen. B) they both involve high mass ionizing stars. C) the shock waves of a supernova can trigger star formaƟon. D) as a result of both processes, lighter elements are transformed into heavier elements. E) All of the above. Answer: _____ E SecƟon Ref: 21.5
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ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 13 Chapter 22 SecƟon 22.1 True or False SecƟon 22.2 MulƟple Choice 22.2.1) Neutron stars and black holes are formed by: A) the star formaƟon process. B) mass transfer in binary star systems. C) novae. D) type I supernovae. E) type II supernovae. Answer: _____ E SecƟon Ref: 22.1 22.2.2) In a neutron star, the core is: A) made of compressed neutrons in contact with each other. B) electrons and protons packed so Ɵghtly they are in contact. C) constantly expanding and contracƟng. D) primarily iron and silicon. E) no longer rotaƟng. Answer: _____ A SecƟon Ref: 22.1 22.2.3) Two important properƟes of young neutron stars are: A) extremely slow rotaƟon and a strong magneƟc field. B) extremely rapid rotaƟon and a weak magneƟc field. C) extremely rapid rotaƟon and a strong magneƟc field. D) no rotaƟon and a weak magneƟc field. E) no rotaƟon and no magneƟc field. Answer: _____ C SecƟon Ref: 22.1 22.2.4) What would happen if mass is added to a 1.4 solar mass white dwarf? A) The star would explode as a nova. B) The star's radius would increase. C) The star would immediately collapse into a black hole. D) The star would erupt as a carbon detonaƟon (type I) supernova. E) The core would collapse as a type II supernova. Answer: _____ D SecƟon Ref: 22.1 22.2.5) Pulsars: A) spin very rapidly when they're young. B) are the cause of gamma-ray bursts. C) spin very slowly when they're young, and gradually spin faster as they age. D) generally form from 25 solar mass stars. E) emit radio in all direcƟons. Answer: _____ A SecƟon Ref: 22.1 22.2.6) What makes the Crab pulsar somewhat unusual among pulsars in general? A) It is the most intense source of X-rays in the sky. B) It is the fastest pulsar known.
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 14 C) It is the oldest pulsar observed. D) Its period is not regular like other pulsars. E) It is rather bright at visible wavelengths. Answer: _____ D SecƟon Ref: 22.2 22.2.7) Whose work with radio band “signals” led to the discovery of pulsars in 1967? A) Jocelyn Bell B) Sir Bernard Lovell C ) Anthony Hewish D) MarƟn Schwarzschild E) Stephen Hawking Answer: _____ A SecƟon Ref: 22.2 22.2.8) Three terrestrial-sized planets in orbits of a fracƟon of an AU have been found near: A) Cygnus X-1. B) a magnetar. C) Supernova 1987A. D) a millisecond pulsar. E) a white dwarf. Answer: _____ D SecƟon Ref: 22.3 22.2.9) Almost half of all known millisecond pulsars are found in what type of object? A) giant molecular clouds B) open clusters C) globular clusters D) emission nebulae E) supernova remnants Answer: _____ C SecƟon Ref: 22.3 22.2.10) X-ray bursters occur in binary star systems. The two types of stars that must be present to make up such an object are: A) a white dwarf and a neutron star. B) a contact binary system of two red giants. C) a white dwarf and a main sequence star. D) a main sequence or giant star and a neutron star in a mass transfer binary. E) two neutron stars in a mass transfer binary. Answer: _____ D SecƟon Ref: 22.3 22.2.11) A proposed explanaƟon for gamma-ray bursters is: A) hypernova-making black holes and bi-polar jets. B) coalescence of a neutron star binary. C) collisions between two white dwarfs. D) Both A and B are possible. E) All three are possible. Answer: _____ D SecƟon Ref: 22.4 22.2.12) What would happen if more mass was added to a 1.4 solar mass neutron star? A) It would erupt as a Type I supernova. B) It could eventually become a black hole, via a hypernova explosion. C) It would grow larger, temporarily becoming a red giant again. D) All of its protons and electrons would turn into quarks. E) It would blow off mass as a gamma ray burster. Answer: _____ B SecƟon Ref: 22.4
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 15 22.2.13) In contrasƟng the distribuƟon of the X-ray and gamma-ray bursts, we find gamma ray bursts: A) are far closer to us, so they appear more luminous. B) are far beyond our Galaxy, at cosmological distances, spread all over the sky, not in the plane of our Galaxy. C) are more closely associated with open than globular clusters. D) can repeat, while the X-ray bursts do not. E) can be observed from the ground, but X-rays are blocked by the ionosphere for ground based observers. Answer: _____ B SecƟon Ref: 22.4 22.2.14) The densely packed neutrons of a neutron star cannot balance the inward pull of gravity if the total mass is: A) less than 1.0 solar masses. B) greater than Schwartzschild's limit of 3 solar masses. C) Chandrasekhar's limit of 1.4 solar masses. D) between 1.4 and 2.0 solar masses. E) greater than 25 solar masses. Answer: _____ B SecƟon Ref: 22.5 22.2.15) What explanaƟon does general relaƟvity provide for gravity? A) Gravity is the result of curved spaceƟme. B) Gravity is directly proporƟonal to the mass of the aƩracƟng body. C) Gravity is inversely proporƟon to the radius of the body. D) Gravity is the opposite of the electromagneƟc force. E) Gravity can affect only massive parƟcles, not massless photons. Answer: _____ A SecƟon Ref: 22.6 22.2.16) An observer on a planet sees a spaceship approaching at 0.5c. A beam of light projected by the ship would be measured by this observer to travel at: A) 0.25c. B) 0.5c. C) c. D) 1.5c. E) 2.5c. Answer: _____ C SecƟon Ref: 22.6 22.2.17) As a spaceship's velocity gets closer to the speed of light: A) its length will increase and its clock will run more slowly. B) its length will decrease and its clock will run faster. C) its length will increase and its clock will run faster. D) its length will decrease and its clock will run more slowly. E) None of these will happen. Answer: _____ B SecƟon Ref: 22.6 22.2.18) The equivalence principle says that a person in an elevator that is in free fall feels the same acceleraƟon as a person in:
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ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 16 A) an elevator going up with an acceleraƟon of g. B) space, far from any gravitaƟonal source acceleraƟng at g. C) an elevator going down with an acceleraƟon of g. D) space, far away from any gravitaƟonal source with no acceleraƟon. E) orbit of Earth acceleraƟng at g upward. Answer: _____ B SecƟon Ref: 22.6 22.2.19) If light from a distant star passes close to a massive body, the light beam will: A) bend towards the star due to gravity. B) conƟnue moving in a straight line. C) change color to a shorter wavelength. D) slow down. E) accelerate due to gravity. Answer: _____ A SecƟon Ref: 22.6 22.2.20) What can we detect from maƩer that has crossed an event horizon? A) Gamma-ray bursts B) Radio waves if the maƩer was traveling fast enough C) Visible light D) X-rays if the maƩer was dense E) Nothing Answer: _____ E SecƟon Ref: 22.7 22.2.21) The key to idenƟfying a black hole candidate in a binary system is that: A) one of the two stars cannot be seen. B) the unseen companion in the system must have a sufficiently high mass. C) the unseen star is a contact binary. D) the system must be a very strong source of radio emissions. E) the visible companion must be an evolving main sequence or giant star. Answer: _____ B SecƟon Ref: 22.8 22.2.22) The largest known black holes: A) create the dark nebulae in the plane of the Milky Way. B) can be no more than 1.4 solar masses, according to Chandrasekhar. C) lie in the cores of the most massive galaxies. D) can be no bigger than a small city, just like neutron stars. E) can be no bigger than the Earth, like white dwarfs. Answer: _____ C SecƟon Ref: 22.8
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 17 Mid Term 2 Answer Sheet Name _______________- 17.1.1)__T__ 17.1.2)__F__ 17.1.3)_F___ 17.1.4)_F___ 17.1.5)_T___ 17.1.6)_F___ 17.1.17)__F__ 17.1.8)__T__ 17.1.9)__F__ 17.1.10)_T___ 17.1.11)__T__ 17.2.1)__D_ 17.2.2)_D__ 17.2.3)_D__ 17.2.4)__D__ 17.2.5)_B__ 17.2.6)_C___ 17.2.7)_D__ 17.2.8)_E___ 17.2.9)_A__ 17.2.10)_D__ 17.2.11)_B__ 17.2.12)__E__ 17.2.13)__C_ 17.2.14)_E__ 17.2.15)_G_ 17.2.16)_D__ 17.2.17)_B__ 17.2.18)_E__ 18.1.1)_T___ 18.1.2)__F__ 18.1.3)_F___ 18.1.4)_F___ 18.1.5)_F___ 18.2.1)__B_ 18.2.2)__C__ 18.2.3)__C__ 18.2.4)_B__ 18.2.5)_E___ 18.2.6)_A__ 18.2.7)_A__ 18.2.8)_D___ 18.2.9)_A___ 18.2.10)__C__ 18.2.11)__B__ 18.2.12)__B_ 18.2.13)__C_ 18.2.14)__E__ 19.2.1)__D__ 19.2.2)__D___ 19.2.3)__B__ 19.2.4)_C__ 19.2.5)_E__ 19.2.6)__D__ 19.2.7)__C__ 19.2.8)_B___ 19.2.9)__A__ 19.2.10)_ C__ 19.2.11)___D___ 19.2.12)__A_ 19.2.13)_E__ 19.2.14)_D__ 19.2.15)_C___ 19.2.16__B__ 20.2.1)__B_ 20.2.2)_D__ 20.2.3)_A__ 20.2.4)__E_ 20.2.5)_A__ 20.2.6)_C___ 20.2.7)__C_ 20.2.8)_C__ 20.2.9)__B__ 20.2.10)_C__ 20.2.11)_C___ 20.2.12)_C___ 20.2.13)_D__ Page 1 21.2.1)_B___ 21.2.2)_C___ 21.2.3)_D___ 21.2.4)_C___ 21.2.5)_A___ 21.2.6)_E___ 21.2.7)__E___ 21.2.8)__B_ 21.2.9)__A__ 21.2.10)_C___ 21.2.11)_B___ 21.2.12)_B___ 21.2.13)_A___ 21.2.14)_D__ 21.2.15)_E___ 22.2.1)_E___ 22.2.2)_A___ 22.2.3)_C___ 22.2.4)_D___ 22.2.5)_A__ 22.2.6)_D____ 22.2.7)_A__ 22.2.8)_D___ 22.2.9)__C__ 22.2.10)__D___ 22.2.11)_D___ 22.2.12)_B___ 22.2.13)_B___ 22.2.14)_B___ 22.2.15)_A___ 22.2.16)_C___ 22.2.17)_B___ 22.2.18)_B___ 22.2.19)_A___ 22.2.20)_E___ 22.2.21)_B___ 22.2.22)_C___ (114)
ASTR 1303 Fall 2022 (base) Chapters 17-22 Midterm 2 Page 18
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