COSMIC PERSPECTIVE
9th Edition
ISBN: 9780135729458
Author: Bennett
Publisher: PEARSON
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Question
Chapter 15, Problem 54EAP
Part a
To determine
The apparent brightness when the sun is located at a distance of 10 light years.
Part b
To determine
The apparent brightness when the sun is located at a distance of 200 light years.
Part c
To determine
The distance of the star in kilometers.
Part d
To determine
The distance of the star in light years.
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Choose the correct statements concerning spectral classes of stars. (Give ALL correct answers, i.e., B, AC, BCD...)
A) Neutral hydrogen lines dominate the spectrum for stars with temperatures around 10,000 K because a lot of the hydrogen is in the n=2 level.
B) Hydrogen lines are weak in type O-stars because most of it is completely ionized.
C) Oh Be A Fine Guy/Girl Kiss Me, is a mnemonic for remembering spectral classes.
D) The spectral sequence has recently been expanded to include L, T, and Y classes.
E) K-stars are dominated by lines from ionized helium because they are so hot.
F) The spectral types of stars arise primarily as a result of differences in temperature.
Star A and Star B are a bound binary at a distance of 20 pc from the Earth. Their
separation is 30 AU. Star A has a mass twice that of Star B. The orbital period of the
binary is 100 years. Assume the stars orbit in circular orbits.
a. What is the parallax of Star A, in units of arcsec? Assume parallax is measured from
the Earth. For part a, ignore the presence of the binary companion.
b.
What is the angular separation we would observe between Star A and Star B, in
units of arcsec? If we compare multiple images of this star system taken across
different months and years, which source of motion will be the dominant effect?
What is the total mass of the binary system (combined mass of Star A and Star B)?
Provide your answer in both kg and solar masses.
c.
d. What is the distance from Star A to the center of mass of the binary system?
Problem 5. Imagine that you observe a star field twice, with a six-month gap between
your observations, and that you see the two sets of stars shown below. Which do you think
is closest to the observer?
Figure 1: Schematic of image of stars A,B, and P taken six months apart.
Problem 6. Suppose the angular separation between stars A and B is 0.5 arcseconds. How
far would you estimate star P to lie from the observer?
Chapter 15 Solutions
COSMIC PERSPECTIVE
Ch. 15 - Prob. 1VSCCh. 15 - Prob. 2VSCCh. 15 - Prob. 3VSCCh. 15 - Prob. 4VSCCh. 15 - Prob. 5VSCCh. 15 - Prob. 6VSCCh. 15 - Prob. 1EAPCh. 15 - Prob. 2EAPCh. 15 - Prob. 3EAPCh. 15 - Prob. 4EAP
Ch. 15 - Prob. 5EAPCh. 15 - Prob. 6EAPCh. 15 - Prob. 7EAPCh. 15 - Prob. 8EAPCh. 15 - Prob. 9EAPCh. 15 - Prob. 10EAPCh. 15 - Prob. 11EAPCh. 15 - Prob. 12EAPCh. 15 - Prob. 13EAPCh. 15 - Prob. 14EAPCh. 15 - Prob. 15EAPCh. 15 - Prob. 16EAPCh. 15 - Prob. 17EAPCh. 15 - Prob. 18EAPCh. 15 - Prob. 19EAPCh. 15 - Prob. 20EAPCh. 15 - Prob. 21EAPCh. 15 - Prob. 22EAPCh. 15 - Prob. 23EAPCh. 15 - Prob. 24EAPCh. 15 - Prob. 25EAPCh. 15 - Prob. 26EAPCh. 15 - Prob. 27EAPCh. 15 - Prob. 28EAPCh. 15 - Prob. 29EAPCh. 15 - Prob. 30EAPCh. 15 - Prob. 31EAPCh. 15 - Prob. 32EAPCh. 15 - Prob. 33EAPCh. 15 - Prob. 34EAPCh. 15 - Prob. 35EAPCh. 15 - Prob. 36EAPCh. 15 - Prob. 37EAPCh. 15 - Prob. 40EAPCh. 15 - Prob. 42EAPCh. 15 - Prob. 44EAPCh. 15 - Prob. 45EAPCh. 15 - Prob. 46EAPCh. 15 - Prob. 47EAPCh. 15 - Prob. 48EAPCh. 15 - Prob. 49EAPCh. 15 - Prob. 50EAPCh. 15 - Prob. 52EAPCh. 15 - Prob. 53EAPCh. 15 - Prob. 54EAPCh. 15 - Prob. 55EAPCh. 15 - Prob. 56EAPCh. 15 - Prob. 57EAPCh. 15 - Prob. 58EAPCh. 15 - Prob. 59EAP
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- Let’s say you’re looking for extrasolar planets. You observe a star that has a spectral shift in the line that is supposed to be at at 656.28011 nm – this star shows this line at 656.28005 nm. What is the radial velocity of star (in m/s) and in what direction in relation to you? a) 27.4 m/s, towards b) 27.4 km/s, away c) -27.4 m/s, toward d) -27.4 km/s, awayarrow_forwardChoose the statements that correctly describe the characteristics of the stars located in the labeled quadrants of the H-R diagram. Luminosityarrow_forwardStellar Classification and H-R Diagram Placement (40 points available). a. Where is your star located on the H-R diagram (luminosity class/region of the diagram, spectral class, luminosity/brightness)? How does this compare to that of The sun ? Discuss the inferences of the specific placement and stellar classification of your star with respect to mass, size/radius, color/temperature, composition? c. Discuss how this placement on the diagram relates to the star’s observed stage of evolution, previous evolution, and expected future evolutionary path. How does this compare to that of the Sun? d. What is the estimated total lifespan of your star and what is the estimated age of your star right now? How does this compare to that of the Sun? All of them is about Lutyen star .arrow_forward12. A star with spectral type MO has a surface temperature of 3750 K and a radius of 0.63 Rsun: How many times more luminous is this star than the Sun? (if it is less luminous enter a number less than one) Answer: Submit All Answers Last Answer: 0.0923 Incorrect, tries 1/5. Hint: Use the Luminosity equation, which says that L is proportional to R^2 T^4. If you keep these as ratios compared to the sun, your L will also come out as a ratio compared to the Sun. This star has a mass of 0.4 Msun- Using the simple approximation that we made in class, what is the main sequence lifetime of this star? You may assume that the lifetime of the sun is 1010 yr. Answer: Submit All Answers Compare this to the lifetime of a MO star listed in Table 22.1 (computed using a more sophisticated approach). Is the value you calculated in the previous problem longer or shorter than what is reported in the table? (L for longer, S for shorter) (You only get one try at this problem.) Answer: Submit All Answersarrow_forwardChoose the correct statements concerning spectral classes of stars. (Give ALL correct answers, i.e., B, AC, BCD...) A) K-stars are dominated by lines from ionized helium because they are so hot. B) Oh Be A Fine Guy/Girl Kiss Me, is a mnemonic for remembering spectral classes. C) The spectral sequence has recently been expanded to include L, T, and Y classes. D) Hydrogen lines are weak in type O-stars because most of it is completely ionized. E) Neutral hydrogen lines dominate the spectrum for stars with temperatures around 10,000 K because a lot of the hydrogen is in the n=2 level. F) The spectral types of stars arise primarily as a result of differences in chemical composition.arrow_forwardWhich of the following can you determine about a star without knowing its distance, and which can you not determine: radial velocity, temperature, apparent brightness, or luminosity? Explain.arrow_forwardReview this spectral data for five stars. Which is the hottest? Coolest? Most luminous? Least luminous? In each case, give your reasoning.arrow_forwardA star has a measured radial velocity of 300 km/s. If you measure the wavelength of a particular spectral line of Hydrogen as 657.18 nm, what was the laboratory wavelength (in nm) of the line? (Round your answer to at least one decimal place.) nm Which spectral line does this likely correspond to? Balmer-alpha (656.3 nm) Balmer-beta (486.1 nm) Balmer-gamma (434.0 nm) Balmer-del ta (410.2 nm)arrow_forwardQ9. If the luminosity of star B is 25 times the luminosity of star A, then find the distance of star A if you know that the two stars have the same brightness, and that star B is 10 astronomical leagues away from us. Use the relationship: BB V BA da dg Q10: If you know that the difference of the apparent magnitude between two stars is equal to 5 magnitudes. What is their brightness? Use this equation Am т 3D ть — т, — —2.5 logio Q11. If the apparent magnitude of the first star in a binary star system is equal 1m and the apparent magnitude of the second star is equal 2m. Calculate the apparent magnitude of the system. Q12. Calculate the distance of a star if you know that its absolute magnitude is equal to (2m) and its apparent magnitude (-2m).arrow_forwardarrow_back_iosSEE MORE QUESTIONSarrow_forward_ios
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