21st Century Astronomy 6E
6th Edition
ISBN: 9780393690675
Author: Laura Kay, Stacy Palen, George Blumenthal
Publisher: W. W. Norton
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Chapter 13, Problem 21QP
To determine
The sequence of temperatures defined by the spectral types
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Astronomers use two basis properties of stars to classify them. These two properties are luminosity and surface temperature. Luminosity usually refers to the brightness of the star relative to the brightness of our sun. Astronomers will often use a star’s color to measure its temperature. Stars with low temperatures produce a reddish light while stars with high temperatures shine with a brilliant blue—white light. Surface temperatures of stars range from 3000o C to 50,000o C. When these surface temperatures are plotted against luminosity, the stars fall into groups. Using the data similar to what you will plot in this activity, Danish astronomer Ejnar Hertzsprung and United States astronomer Henry Norris Russell independently arrived at similar results in what is now commonly referred to as the HR Diagram.
Procedures:1. Read the Background Information
2. On the graph paper provided. Place a number next to the star according to its luminosity and surface temperature listed in the data…
"51 Pegasi" is the name of the first normal star (besides the Sun) around which a planet was discovered. It is in the constellation Pegasus the horse. Its parallax is measured to be 0.064 arcsec.
a. What is its distance from us?
b. The apparent brightness is 1.79 × 10-10 J/(s·m2 ). What is the luminosity? How does that compare with that of the Sun? Look up the temperature: how do
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).
Chapter 13 Solutions
21st Century Astronomy 6E
Ch. 13.1 - Prob. 13.1CYUCh. 13.2 - Prob. 13.2CYUCh. 13.3 - Prob. 13.3CYUCh. 13.4 - Prob. 13.4CYUCh. 13 - Prob. 1QPCh. 13 - Prob. 2QPCh. 13 - Prob. 3QPCh. 13 - Prob. 4QPCh. 13 - Prob. 5QPCh. 13 - Prob. 6QP
Ch. 13 - Prob. 7QPCh. 13 - Prob. 8QPCh. 13 - Prob. 9QPCh. 13 - Prob. 10QPCh. 13 - Prob. 11QPCh. 13 - Prob. 12QPCh. 13 - Prob. 13QPCh. 13 - Prob. 14QPCh. 13 - Prob. 15QPCh. 13 - Prob. 16QPCh. 13 - Prob. 17QPCh. 13 - Prob. 18QPCh. 13 - Prob. 19QPCh. 13 - Prob. 20QPCh. 13 - Prob. 21QPCh. 13 - Prob. 22QPCh. 13 - Prob. 23QPCh. 13 - Prob. 24QPCh. 13 - Prob. 25QPCh. 13 - Prob. 26QPCh. 13 - Prob. 27QPCh. 13 - Prob. 28QPCh. 13 - Prob. 29QPCh. 13 - Prob. 30QPCh. 13 - Prob. 31QPCh. 13 - Prob. 32QPCh. 13 - Prob. 33QPCh. 13 - Prob. 34QPCh. 13 - Prob. 35QPCh. 13 - Prob. 36QPCh. 13 - Prob. 37QPCh. 13 - Prob. 38QPCh. 13 - Prob. 39QPCh. 13 - Prob. 40QPCh. 13 - Prob. 41QPCh. 13 - Prob. 42QPCh. 13 - Prob. 43QPCh. 13 - Prob. 44QPCh. 13 - Prob. 45QP
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- . The spectrum of Star A peaks at 700 nm. The spectrum of Star B peaks at 470 nm. We know nothing about what stage of stellar evolution either of these stars are in. Which of the following are true? A. Star A has a higher luminosity than Star B. B. Star B has a higher luminosity than Star A. C. Star A is cooler than Star B. D. Not enough information to comment on their luminosities. E. B and C F. C and Darrow_forwardA star with a radius 1.7 times that of the Sun has a surface temperature T=10,000 K. Calculate the luminosity of this star and express your answer in units of the Solar luminosity (the Solar luminosity = 3.84 x 1026 W and the Solar radius = 7 x %3D 108 m). Choose the option below that most closely matches your answer. Select one: а. 20 O b. 100. O C. 26. O d. 5. O e. 1000arrow_forwardChoose the statements that correctly describe the characteristics of the stars located in the labeled quadrants of the H-R diagram. Luminosityarrow_forwardA star such as our Sun will eventually evolve to a “red giant” star and then to a “white dwarf” star. A typical white dwarf is approximately the size of Earth, and its surface temperature is about 2.4 × 104 K. A typical red giant has a surface temperature of 3.2 × 103 K and a radius ~90000 times larger than that of a white dwarf. Take the radius of the red giant to be 6 × 1010 m. What is the average radiated power per unit area of the red giant?_________W/m2 What is the average radiated power per unit area of the white-dwarf?________W/m2 What is the total power radiated by the red giant? _________W What is the total power radiated by the white dwarf? ________W Please show full work! Thank you!arrow_forwardThe spectral type of a star is directly related to its color. Recall that a star emits light as a blackbody, which has a particular shape to its spectrum, as shown in this figure. Based on this, what basic property of a star determines its color (and thus its spectral type)? Choose one: A. age B. composition C. radius D. temperaturearrow_forwardA star has a measured radial velocity of 100 km/s. If you measure the wavelength of a particular spectral line of Hydrogen as 486.42 nm, what was the laboratory wavelength (in nm) of the line? (Round your answer to at least one decimal place.) Which spectral line does this likely correspond to? Balmer-alpha (656.3 nm) Balmer-beta (486.1 nm) Balmer-gamma (434.0 nm) Balmer-delta (410.2 nm)arrow_forwardA star has a surface temperature of T = 10,000 K and a radius three times that of the Sun, R = 3R (recall that symbolizes the Sun). What is its luminosity, L, in units of solar luminosities, L? Give your answer to three significant figures. answer, expressed in solar luminosities, tells how many times more luminous this star is than the Sun.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_forward1 Solar constant, Sun, and the 10 pc distance! The luminosity of Sun is + 4- 1026 W - 4- 1033ergs-1, The Sun is located at a distance of m from the Earth. The Earth receives a radiant flux (above its atmosphere) of F = 1365W m- 2, also known as the solar constant. What would have been the Solar contact if the Sun was at a distance of 10 pc ? 1AU 1 1.5-+ 1011arrow_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_forwardSpectral types are an indicator of temperature. For the first 10 stars in Appendix J, the list of the brightest stars in our skies, estimate their temperatures from their spectral types. Use information in the figures and/or tables in this chapter and describe how you made the estimates.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_forwardarrow_back_iosSEE MORE QUESTIONSarrow_forward_ios
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