Foundations of Astronomy (MindTap Course List)
14th Edition
ISBN: 9781337399920
Author: Michael A. Seeds, Dana Backman
Publisher: Cengage Learning
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Chapter 9, Problem 13P
To determine
The ratio of the luminosities.
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Using the HR diagram, what is the approximate range of relative luminosities covered for a main sequence star at 10 000 K?
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where d is the distance in parsecs, mV and MV are the apparent and absolute visual magnitude respectively.)
A star with spectral type A0 has a surface temperature of 9600 K and a radius of 2.2 RSun. How many times more luminous is this star than the Sun? (if it is less luminous enter a number less than one)
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This star has a mass of 3.3 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.
Chapter 9 Solutions
Foundations of Astronomy (MindTap Course List)
Ch. 9 - Prob. 1RQCh. 9 - Why was the Hipparcos satellite able to make more...Ch. 9 - Prob. 3RQCh. 9 - Prob. 4RQCh. 9 - Prob. 5RQCh. 9 - Prob. 6RQCh. 9 - Prob. 7RQCh. 9 - Prob. 8RQCh. 9 - Prob. 9RQCh. 9 - Prob. 10RQ
Ch. 9 - Prob. 11RQCh. 9 - Prob. 12RQCh. 9 - Prob. 13RQCh. 9 - Prob. 14RQCh. 9 - Prob. 15RQCh. 9 - Prob. 16RQCh. 9 - Prob. 17RQCh. 9 - Prob. 18RQCh. 9 - Prob. 19RQCh. 9 - Prob. 20RQCh. 9 - Prob. 21RQCh. 9 - Prob. 22RQCh. 9 - Prob. 23RQCh. 9 - Prob. 24RQCh. 9 - Prob. 25RQCh. 9 - Prob. 26RQCh. 9 - Prob. 27RQCh. 9 - Prob. 28RQCh. 9 - Prob. 29RQCh. 9 - Prob. 30RQCh. 9 - Prob. 31RQCh. 9 - Prob. 32RQCh. 9 - How Do We Know? In what way are basic scientific...Ch. 9 - Prob. 1PCh. 9 - Prob. 2PCh. 9 - Prob. 3PCh. 9 - Prob. 4PCh. 9 - Complete the following table:Ch. 9 - Prob. 6PCh. 9 - Prob. 7PCh. 9 - Prob. 8PCh. 9 - Prob. 9PCh. 9 - Prob. 10PCh. 9 - Prob. 11PCh. 9 - Prob. 12PCh. 9 - Prob. 13PCh. 9 - Prob. 14PCh. 9 - Prob. 15PCh. 9 - Prob. 16PCh. 9 - Prob. 17PCh. 9 - Prob. 18PCh. 9 - Prob. 19PCh. 9 - Prob. 20PCh. 9 - Prob. 1SOPCh. 9 - Prob. 2SOPCh. 9 - Prob. 3SOPCh. 9 - Look at the image on the opening page of this...Ch. 9 - Prob. 2LTLCh. 9 - Prob. 3LTLCh. 9 - Prob. 4LTL
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- Appendix J lists the stars that appear brightest in our sky. Are most of these hotter or cooler than the Sun? Can you suggest a reason for the difference between this answer and the answer to the previous question? (Hint: Look at the luminosities.) Is there any tendency for a correlation between temperature and luminosity? Are there exceptions to the correlation?arrow_forwardFor the PP chain 0.7% of the mass participating in nuclear fusion is liberated as energy which produces a star's luminosity. Assume that the core of a main sequence star consists of 10% of its total mass. Hence, estimate the lifetime of a star on the main sequence in terms of its luminosity L/L. Give your answer in years. You may use the observed mass-luminosity relation L x M³.5, where M is the star's total mass. Using typical values, calculate estimates for the main sequence lifetime of a KO star and a 05 star. Describe briefly why your estimate might be more accurate for K stars compared to O stars.arrow_forwardUsing the HR diagram what is the approximate range of relative luminosities covered for a main sequence star at 10 000 K?arrow_forward
- A star with spectral type A0 has a surface temperature of 9600 K and a radius of 2.2 RSun. How many times more luminous is this star than the Sun? (if it is less luminous enter a number less than one) This star has a mass of 3.3 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. Compare this to the lifetime of a A0 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.)arrow_forwardA 46M Sun main sequence star loses 1 Msun of mass over 105 years. (Due to the nature of this problem, do not use rounded intermediate values in your calculations including answers submitted in WebAssign.) How many solar masses did it lose in a year? By how much will its luminosity decrease if this mass loss continues over 0.8 million years? Due to the nature of this problem, for all parts, do not use rounded intermediate values in your calculations-including answers submitted in WebAssign. To determine the number of solar masses lost per year, divide the mass lost by the number of years over which it was lost. Mlost tlost-yr Part 1 of 3 dM = dM = MSun/yrarrow_forwardFinally estimate the lifetime of an M0 spectral type star if the total mass of the star is M = 0.51M⊙ , and it has a total luminosity L = 7.7× 10−2L⊙. Make the same assumptions as the previous two problems. How does your calculated Main Sequence lifetime for the M0 type star compare to the Main Sequence lifetime you calculated for the Sun?arrow_forward
- Using solar units, we find that a star has 4 times the luminosity of the Sun, a mass 1.25 times the mass of the Sun, and a surface temperature of 4090 K (take the Sun's surface temperature to be 5784 K for the sake of this problem). This means the star has a radius of.................... solar radii and is a .................... star (use the classification).arrow_forwardFor a main sequence star with luminosity L, how many kilograms of hydrogen is being converted into helium per second? Use the formula that you derive to estimate the mass of hydrogen atoms that are converted into helium in the interior of the sun (LSun = 3.9 x 1026 W). (Note: the mass of a hydrogen atom is 1 mproton and the mass of a helium atom is 3.97 mproton. You need four hydrogen nuclei to form one helium nucleus.)arrow_forwardThe Orion Nebula is a gas-rich region in which stars are being born. The nebula is at a distance of about 1344 lyr from Earth.Suppose you observe a star in the Orion Nebula to have an apparent magnitude of 6.75. Calculate the absolute magnitudeof the star. Also calculate the luminosity of the star in units of the solar luminosity (knowing that the absolute magnitude ofthe Sun is 4.8).arrow_forward
- Assuming that at the end of the He burning phase of the stellar core (r < R_core) has no H or He or other metals and is composed completely of Carbon, X=Y=0, X_c = 1 ; The envelope above the core has a normal stellar composition ( r > R_core). Calculate the length of time in years that a 1M_sol and 10M_sol star will live on the horizontal branch or the time between the start and end of the He burning phase. Assume that the normal relationship between mass and luminosity holds for horizontal branch stars. Please be as detailed as possiblearrow_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 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.arrow_forwardAs we have discussed, Sirius B in the Sirius binary system is a white dwarf with MB ∼ 1M , LB ∼ 0.024L ,and rB ∼ 0.0084r . For such a white dwarf, the temperature at the center is estimated to be ∼ 107 K.If Sirius B’s luminosity were due to hydrogen fusion, what is the upper limit of the mass fraction of thehydrogen in such a white dwarf?Step 1: Calculate the observed energy production rate per unit mass (remember luminosity is energy outputper unit time).Step 2: Use the per unit mass energy generation rate of hydrogen fusion (via PP chain) to estimate thepossible hydrogen mass fraction given the condition at the center of the white dwarf.arrow_forward
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