We learned in class that, when stars collapse under their own gravity, they conserve angular momentum, which is proportional to mass times radius times rotational speed. Suppose the entire sun (radius 695,700 km) were to collapse to a neutron star with a radius of only 10 km, Before the collapse, the rotational speed at the equator = 2.0 km/s, and the rotational period is 25 days. Using the same steps that you used for the white dwarf calculations, calculate the final rotation period if the entire sun were to collapse to a 10 km radius neutron star. Give your answer in units of seconds. Answer: Check
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A: mass of the sun, Msun=1.989×1030 kg Radius of the sun, R=85.074 km Volume, V=43πR3
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A: Given, Radius of remnant of supernova = 3.65 pc = 1.116×1014km Rate of expanding = 4850 km/s
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A: Given, mass of sun = mass of neutron star (m) = 1.989×1030 kg radius = 86.31 km
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A: The original mass f the red giant is 12.7 MSun.
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Q: We will take a moment tổ compare ROw BrigriLIy a Wiite uwan stal sines Compdleu 10 a leu glant 3lai.…
A: Given: Tw=10,000 KTR=5,000 KRw=1100RsunRR=100Rsun we have to find ratio of Luminosity: LRLw=?
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- Generally speaking, a low-mass star ends up as a white dwarf while a high-mass explodes. Why/How does the amount of mass determine the star's fate?Indicate whether the following statements are true or false. (Select T-True, F-False. If the first is T and the rest F, enter TFFFFF). A) White dwarfs are small dense objects about the size of the Earth. B) White dwarfs are composed mostly of hydrogen. C) A planetary nebula forms when a star violently explodes. D) A planetary nebula is the remnant of the outer envelope of a star. E) A white dwarf is the remnant of the star's core visible after the outer layers have been ejected.QUESTION 16 Use the figure shown below to complete the following statement: A low-mass protostar (0.5 to 8M the mass compared to our sun) remains roughly constant in decreases in until it makes a turn towards the main sequence, as it follows its evolutionary track. Protostars of different masses follow diferent paths on their way to the main sequence. 107 Luminosity (L) 10 105 10 107 10² 101 1 10-1 10-2 10-3 Spectral type 0.01 R 0.001 Re 60 M MAIN SEQUENCE 40,000 30,000 20 Mau 10 Mgun 5 Mun 0.1 Run Ren radius; temperature luminosity; radius 3 Min. 05 BO temperature; luminosity Oluminosity: temperature radius: luminosity 1 M 10,000 6000 Surlace temperature (K) 1,000 Rs 2 M STAR L 0.8 M B5 AO FOGO КБ МБ -10 +10 3000 Absolute visual magnitude and
- Match the spectral type and luminosity class to theletters shown on the Hertzsprung-Russell diagram 1) A WD (White Dwarf)2) G V (Main Sequence) 3) M V (Main Sequence)4) M I (Supergiant)5) G III (Giant)If a 1.40 MSun neutron star has a radius of 10.0 km, what is the radius (in km) of a 2.15 MSun neutron star? (Use the mass-radius relationship R ∝ M−1/3) What is the escape velocity (in km/s) from the surface of a 1.5 M neutron star? From a 3.0 M neutron star? (Hint: Use the formula for escape velocity, Ve = 2GM r ; make sure to express quantities in units of meters, kilograms, and seconds. Assume a neutron star has a radius of 11 km and assume the mass of the Sun is 1.99 ✕ 1030 kg.) 1.5 M neutron star km/s3.0 M neutron star km/sDuring the collapse of a supernova explosion, calculate the change in gravitational potential energy associated with the core size. Assume a typical core mass of 1.4 Msun and an initial radius of 1000 km.
- If a circular accretion disk around a 1.4 M, neutron star has a radius of 8.00 x 10° km as measured from the center of the neutron star to the edge of the disk, what is the orbital velocity (in km/s) of a gas particle located at its outer edge? (The mass of the Sun is GM 1.99 x 1030 kg. Hint: Use the circular orbit velocity formula, V. = -; make sure to express quantities in units of meters, kilograms, and seconds.) km/sA supernova remnant is now 3.85 pc in radius and is expanding at 3,350 km/s. Approximately how many years ago did the supernova occur? (Note: 1 pc = 3.1 ✕ 1013 km and 1 yr = 3.2 ✕ 107 s.)Say that a white dwarf has about the same radius as the earth and about the same mass as the sun. Quantitatively compare the bulk density of the white dwarf to the bulk density of the sun.
- If a neutron star has a radius of 12 km and rotates 1,352 times a second, what is the speed at which a point on the surface at the neutron star's equator is moving? Express your answer as a fraction of the speed of light. (Note: The speed of light is 3 ✕ 105 km/s.)A main sequence star of mass 25 M⊙has a luminosity of approximately 80,000 L⊙. a. At what rate DOES MASS VANISH as H is fused to He in the star’s core? Note: When we say “mass vanish '' what we really mean is “gets converted into energy and leaves the star as light”. Note: approximate answer: 3.55 E14 kg/s b. At what rate is H converted into He? To do this you need to take into account that for every kg of hydrogen burned, only 0.7% gets converted into energy while the rest turns into helium. Approximate answer = 5E16 kg/s c. Assuming that only the 10% of the star’s mass in the central regions will get hot enough for fusion, calculate the main sequence lifetime of the star. Put your answer in years, and compare it to the lifetime of the Sun. It should be much, much shorter. Approximate answer: 30 million years.Betelgeuse is a nearby supergiant that will eventually explode into a supernova. Let's see how awesome it would look. At peak brightness, the supernova will have a luminosity of about 10 billion times the Sun. It is 600 light-years away. All stellar brightnesses are compared with Vega, which has an intrinsic luminosity of about 60 times the Sun, a distance of 25 light-years, an absolute magnitude of 0.6 and an apparent magnitude of 0 (by definition). a) At peak brightness, how many times brighter will Betelgeuse be than Vega? b) Approximately what apparent magnitude does this correspond to? c) The Sun is about -26.5 apparent magnitude. What fraction of the Sun's brightness will Betelgeuse be?