UNIVERSE (LOOSELEAF):STARS+GALAXIES
6th Edition
ISBN: 9781319115043
Author: Freedman
Publisher: MAC HIGHER
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Chapter 19, Problem 38Q
To determine
The reason behind the more massive star in Algol binary system is a main-sequence star while the less massive star is a red giant, even though massive main stars turned into red giants more quickly than the less massive stars.
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A red giant star might have radius = 104 times the solar radius,
and luminosity = 1730 times solar luminosity.
Use the data given below to calculate the temperature
at the surface of the red giant star.
Data:
solar radius R = 7 x 108 meters
solar luminosity L = 4 x 1026 watts
Stefan-Boltzmann constant
a = 5.67 x 10-8 W m² K-4
(in K)
A: 1226 OB: 1434 OC: 1678 OD: 1963 OE: 2297 OF: 2688 OG: 3145 OH: 3679
We will take a moment to compare how brightly a white dwarf star shines compared to a red giant star. For the sake of this problem, let's assume a white dwarf has a temperature around 10,000 K and a red giant has a temperature around 5,000 K. As for their stellar radiatin, the white dwarf has a radius about 1/100th that of the Sun, and a red giant has a radius around 100 times larger than the Sun.
With this in mind, how does the luminosity of a red giant star compare to that of a white dwarf (Hint: do not try to enter all of these numbers into the luminosity equation {it won't go well}; instead, remember that you are only interested in the ratio between the two, so all common units and components can be divided out)?
Please enter your answer in terms of the luminosity of the red giant divided by the luminosity of the white dwarf and round to two significant figures. Also, please avoid using commas in your answer.
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?
Chapter 19 Solutions
UNIVERSE (LOOSELEAF):STARS+GALAXIES
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- 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 andarrow_forwardWe will take a moment to compare how brightly a white dwarf star shines compared to a red giant star. For the sake of this probler, lets assume a white dwarf has a temperature around 10,000 K and a red giant has a temperature around 5,000 K. As for their stellar radii, the white dwarf has a radius about 1/100th that of the Sun and a red giant has a radius around 100 times larger than the Sun. With this in mind, how does the luminosity of a red giant star compare to that of a white dwarf (Hint: do not try to enter all of these numbers into the luminosity equation fit won't go well); instead, remember that you are only interested in the ratio between the two, so all common units and components can be divided out)? Please enter your answer in terms of the luminosity of the red giant divided by the luminosity of the white dwarf and round to two significant figures. Also, please avoid using commas in your answer. A Moving to another question will save this response. Question 1 of 32 >» 31…arrow_forwardOne way to calculate the radius of a star is to use its luminosity and temperature and assume that the star radiates approximately like a blackbody. Astronomers have measured the characteristics of central stars of planetary nebulae and have found that a typical central star is 16 times as luminous and 20 times as hot (about 110,000 K) as the Sun. Find the radius in terms of the Sun’s. How does this radius compare with that of a typical white dwarf?arrow_forward
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