Universe: Stars And Galaxies
6th Edition
ISBN: 9781319115098
Author: Roger Freedman, Robert Geller, William J. Kaufmann
Publisher: W. H. Freeman
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Question
Chapter 19, Problem 42Q
To determine
(a)
The average distance between the two stars of W UrsaeMajoris.
To determine
(b)
Whether or not, the statement that this system is an overcontact binary is consistent with the radii of the two stars and their average separation.
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An O8 V star has an apparent visual magnitude of +5. Use the method of spectroscopic parallax to estimate the distance to the star (in pc). (Hints: Refer to one of the H–R diagrams in the chapter, and use the magnitude–distance formula,
d = 10(mV − MV + 5)/5
where d is the distance in parsecs, mV and MV are the apparent and absolute visual magnitude respectively.)
velocity curve for a double line
spectroscopic binary is shown in the sketch.
The system is viewed edge-on, i.e., with an
inclination angle of i = 90°, so that the
maximum possible Doppler shifts for this
system are observed.
400
300
So = U, Ani
200
t0 = v Ain i
100
-100
-200
-300
400
O 1 2 3 1 s 1 8: 10
Time (days)
Find the orbital period of this binary in days.
Doppler Velocity (krn/sec)
a) Calculate the period of the solar system's orbit around the Milky Way. Assume that we are 8.5
kpc from the galactic center and assume that the mass of the Milky Way interior to our orbit is
~ 10¹¹ solar masses.
Alpha Centauri is a multiple star system only 1.34 parsecs away. The apparent magnitudes of the
two main stars are:
a Cen A: my = +0.01;
a Cen B: my = +1.33.
b) Calculate the ratio of the flux we receive in the V filter from a Cen A to the flux we receive
from a Cen B.
c) Calculate the absolute magnitude My of a Cen B.
Chapter 19 Solutions
Universe: Stars And Galaxies
Ch. 19 - Prob. 1QCh. 19 - Prob. 2QCh. 19 - Prob. 3QCh. 19 - Prob. 4QCh. 19 - Prob. 5QCh. 19 - Prob. 6QCh. 19 - Prob. 7QCh. 19 - Prob. 8QCh. 19 - Prob. 9QCh. 19 - Prob. 10Q
Ch. 19 - Prob. 11QCh. 19 - Prob. 12QCh. 19 - Prob. 13QCh. 19 - Prob. 14QCh. 19 - Prob. 15QCh. 19 - Prob. 16QCh. 19 - Prob. 17QCh. 19 - Prob. 18QCh. 19 - Prob. 19QCh. 19 - Prob. 20QCh. 19 - Prob. 21QCh. 19 - Prob. 22QCh. 19 - Prob. 23QCh. 19 - Prob. 24QCh. 19 - Prob. 25QCh. 19 - Prob. 26QCh. 19 - Prob. 27QCh. 19 - Prob. 28QCh. 19 - Prob. 29QCh. 19 - Prob. 30QCh. 19 - Prob. 31QCh. 19 - Prob. 32QCh. 19 - Prob. 33QCh. 19 - Prob. 34QCh. 19 - Prob. 35QCh. 19 - Prob. 36QCh. 19 - Prob. 37QCh. 19 - Prob. 38QCh. 19 - Prob. 39QCh. 19 - Prob. 40QCh. 19 - Prob. 41QCh. 19 - Prob. 42QCh. 19 - Prob. 43QCh. 19 - Prob. 44QCh. 19 - Prob. 45QCh. 19 - Prob. 46QCh. 19 - Prob. 47QCh. 19 - Prob. 48QCh. 19 - Prob. 49QCh. 19 - Prob. 50QCh. 19 - Prob. 51QCh. 19 - Prob. 52QCh. 19 - Prob. 53Q
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