21ST C ASTRO EBOOK+SW5=SS+VGCRD+LEARN/DO
6th Edition
ISBN: 9780393870152
Author: PALEN
Publisher: Norton, W. W. & Company, Inc.
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Chapter 17, Problem 20QP
To determine
The reason why Cepheids are good indicators for determining stellar distances.
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Question 32
Consider three Main Sequence stars, an O tar, an F star and a K star, each with an
apparent magnitude of 2. Which star is the most luminous?
They're all the same luminosity.
The O star
The F star
The K star
Question 33
Consider three Main Sequence stars, an O star, an F star and a K star, each with an
apparent magnitude of 2. Which star appears the brightest in the night sky?
The O star
The F star
O The K star
O They all appear the same.
Please answer
both
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).
QUESTION 10
Which of the following Cepheid variable stars would appear to be the brightest from Earth?
A Cepheid variable star that is 10,000 times as luminous as the sun.
A Cepheid variable star with a period of 10 days.
A Cepheid variable star with a period of 3 days.
There is not enough information given.
Chapter 17 Solutions
21ST C ASTRO EBOOK+SW5=SS+VGCRD+LEARN/DO
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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- The mass-luminosity relation describes the mathematical relationship between luminosity and mass for main sequence stars. It describes how a star with a mass of 4 M⊙ would have a luminosity of ______ L⊙. If a star has a radius 1/2 that of the Sun and a temperature 4 that of the Sun, how many times higher is the star's luminosity than that of the Sun? (If it is smaller by a factor of 8, you would write 0.125 because 1/8=0.125) If a star has a radius 2 times larger than the Sun's and a luminosity 1/4th that of the Sun, how many times higher is the star's temperature than that of the Sun? (If it is smaller by a factor of 8, you would write 0.125 because 1/8=0.125) If a star has a surface temperature 2 times lower than the Sun's and a luminosity the same as the Sun, how many times larger is the star than the Sun? (If it is smaller by a factor of 8, you would write 0.125 because 1/8=0.125)arrow_forwardAn 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.)arrow_forwardIf parallax of a star is 0.22 arc-seconds and its apparent brightness is 50 x 10-6 W/m2 . What is its luminosity? 2.5 x 1030 W 3.2 x 1026 W 1.2 x 1031 W 5.3 x 1034 Warrow_forward
- A star has a radius of 2.6 R⊙, and a temperature of 9,758 K. What is the luminosity of this star (answer in solar luminosity units L⊙). [HINT: the temperature of the Sun is about 5800 K]arrow_forwardThe lowest mass for a true star is 1/12 the mass of the sun. What is the luminosity of this star (in units of the sun’s luminosity) based upon mass luminosity relationship? Use the exponent of 4 for easy calculations instead of 3.9arrow_forward2. If Vega is apparent magnitude zero, and Deneb first magnitude, then Vega must be 2.5× hotter than Deneb. Vega is 2.5× brighter than Deneb. Vega is about 100× brighter than Deneb. Deneb is one magnitude brighter than Vega. Deneb must be a main sequence star, and Vega a giant.arrow_forward
- A star has a parallax angle of 0.0270 arcseconds and an apparent magnitude of 4.641. The distance to this star is 37.03 parsecs and the absolute magintude is 1.79. 18: What is the luminosity of this star? (HINT: The luminosity of the Sun is 3.85×1026 W.) Using the Forumla M1 - M2 = -2.5 log(L1/L2) the absolute magnitude of the Sun is 4.8arrow_forward12: 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) Answer: 36.854 13:This star has a mass of 3.3 MSun. what is the main sequence lifetime of this star? You may assume that the lifetime of the sun is 1010 yr. Please answer question 13 thank you.arrow_forwardThe apparent magnitude of a star is observed to vary between m = +0.4 and m = +0.1 because the star pulsates and hence continuously changes its radius and temperature. When at its peak brightness, the star’s radius has increased by a factor of two compared to its value at the mini- mum brightness. Determine the value of T+/T−, where T+ is the temperature when the star is at its peak brightness and T− is the temperature when the star is at it minimum brightness. Note: we expect T+/T− < 1 because the star’s temperature decreases as its radius increases.arrow_forward
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