21st Century Astronomy
6th Edition
ISBN: 9780393428063
Author: Kay
Publisher: NORTON
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Question
Chapter 17, Problem 18QP
To determine
The reason why the core of a high-mass star does not become degenerate as the core of a low-mass star does.
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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?
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
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
Chapter 17 Solutions
21st Century Astronomy
Ch. 17.1 - Prob. 17.1CYUCh. 17.2 - Prob. 17.2CYUCh. 17.3 - Prob. 17.3CYUCh. 17.4 - Prob. 17.4CYUCh. 17 - Prob. 1QPCh. 17 - Prob. 2QPCh. 17 - Prob. 3QPCh. 17 - Prob. 4QPCh. 17 - Prob. 5QPCh. 17 - Prob. 6QP
Ch. 17 - Prob. 7QPCh. 17 - Prob. 8QPCh. 17 - Prob. 9QPCh. 17 - Prob. 10QPCh. 17 - Prob. 11QPCh. 17 - Prob. 12QPCh. 17 - Prob. 13QPCh. 17 - Prob. 14QPCh. 17 - Prob. 15QPCh. 17 - Prob. 16QPCh. 17 - Prob. 17QPCh. 17 - Prob. 18QPCh. 17 - Prob. 19QPCh. 17 - Prob. 20QPCh. 17 - Prob. 21QPCh. 17 - Prob. 22QPCh. 17 - Prob. 23QPCh. 17 - Prob. 24QPCh. 17 - Prob. 25QPCh. 17 - Prob. 26QPCh. 17 - Prob. 27QPCh. 17 - Prob. 28QPCh. 17 - Prob. 29QPCh. 17 - Prob. 30QPCh. 17 - Prob. 31QPCh. 17 - Prob. 32QPCh. 17 - Prob. 33QPCh. 17 - Prob. 34QPCh. 17 - Prob. 35QPCh. 17 - Prob. 36QPCh. 17 - Prob. 37QPCh. 17 - Prob. 38QPCh. 17 - Prob. 39QPCh. 17 - Prob. 40QPCh. 17 - Prob. 41QPCh. 17 - Prob. 42QPCh. 17 - Prob. 43QPCh. 17 - Prob. 44QPCh. 17 - Prob. 45QP
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