Understanding Our Universe
3rd Edition
ISBN: 9780393614428
Author: PALEN, Stacy, Kay, Laura, Blumenthal, George (george Ray)
Publisher: W.w. Norton & Company,
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Chapter 10, Problem 31QAP
To determine
The reason why O stars and G stars have weak absorption lines; the reason why A stars have strongest lines.
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Analyze the multi-wavelength images below and answer the few questions that follows up :
1. Where do you see the higher energy phenomena? What are they? Are they visible in any image? Why?2. Where are the young stars? What colour do they have? Are they visible in any image? Why?3. Where are the old stars? What colour do they have? Are they visible in any image? Why?
1. If a star has a surface temperature of 3000 K but a luminosity 150 times greater than our Sun, what size is this star? Give your answer in units of the solar radius.
2. At what wavelengths do stars of surface temperates 20 000 K, 10 000 K, and 3000 K have their peak intensity?
3. If the Hα absorption line in the spectrum of a galaxy is observed at a wavelength of 6715 ˚A, at what speed is the galaxy moving away from us?
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.
Chapter 10 Solutions
Understanding Our Universe
Ch. 10.1 - Prob. 10.1CYUCh. 10.2 - Prob. 10.2CYUCh. 10.3 - Prob. 10.3CYUCh. 10.4 - Prob. 10.4CYUCh. 10 - Prob. 1QAPCh. 10 - Prob. 2QAPCh. 10 - Prob. 3QAPCh. 10 - Prob. 4QAPCh. 10 - Prob. 5QAPCh. 10 - Prob. 6QAP
Ch. 10 - Prob. 7QAPCh. 10 - Prob. 8QAPCh. 10 - Prob. 9QAPCh. 10 - Prob. 10QAPCh. 10 - Prob. 11QAPCh. 10 - Prob. 12QAPCh. 10 - Prob. 13QAPCh. 10 - Prob. 14QAPCh. 10 - Prob. 15QAPCh. 10 - Prob. 16QAPCh. 10 - Prob. 17QAPCh. 10 - Prob. 18QAPCh. 10 - Prob. 19QAPCh. 10 - Prob. 20QAPCh. 10 - Prob. 21QAPCh. 10 - Prob. 22QAPCh. 10 - Prob. 23QAPCh. 10 - Prob. 24QAPCh. 10 - Prob. 25QAPCh. 10 - Prob. 26QAPCh. 10 - Prob. 27QAPCh. 10 - Prob. 28QAPCh. 10 - Prob. 29QAPCh. 10 - Prob. 31QAPCh. 10 - Prob. 32QAPCh. 10 - Prob. 33QAPCh. 10 - Prob. 34QAPCh. 10 - Prob. 35QAPCh. 10 - Prob. 36QAPCh. 10 - Prob. 37QAPCh. 10 - Prob. 38QAPCh. 10 - Prob. 39QAPCh. 10 - Prob. 40QAPCh. 10 - Prob. 41QAPCh. 10 - Prob. 42QAPCh. 10 - Prob. 43QAPCh. 10 - Prob. 44QAPCh. 10 - Prob. 45QAP
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- Select all the statements below regarding spectral lines that are true. The stars with the most prominent hydrogen absorption lines are O stars. K stars have many more spectral lines than B stars. Heavy elements generally have fewer spectral lines than light elements. An absorption line is produced when a cooler gas absorbs light from a bright background continuum light source. Emission lines are produced when electrons jump from low energy levels to high ones. The longest wavelength Hydrogen Balmer line is red.arrow_forwardWhy don’t we see hydrogen Balmer lines in the spectra of stars with temperatures of 3,200 K? a. There is no hydrogen in stars this cool. b. The stars are hot enough that most of the hydrogen is ionized and the atoms cannot absorb energy. c. These stars are so cool that nearly all of the hydrogen atoms are in the ground state. d. Stars of this temperature are too cool to produce an absorption spectrum. e. Stars of this temperature are too hot to produce an absorption spectrum.arrow_forwardAll massive main sequence stars reside in clouds of glowing gas. The four powerful stars in the center of the Orion Nebula are good examples. Lower mass stars like the Sun generally don't have clouds of gas around them. a. Why do powerful stars reside in gas clouds? b. What is making the gas glow exactly? For the last question, refer to the surface temperature of these stars, and to Wien's Law.arrow_forward
- Tutorial Star A has a temperature of 5,000 K and Star B has a temperature of 6,000 K. At what wavelengths (in nm) will each of these star's intensity be at its maximum? If the temperatures of the stars increase, the wavelength of maximum intensity. What is the temperature (in K) of a star that appears most intense at a wavelength of 829 nm? Part 1 of 4 Wien's Law tells us how the temperature of a star determines the wavelength of maximum intensity or at what wavelength the star appears brightest. 2.90 x 106 TK If the temperature is in kelvin (K) then A is in nanometers (nm). Anm ^A = AB = = Part 2 of 4 To determine the wavelengths of maximum intensity for the two stars: 2.90 x 106 2.90 x 106 K nm nmarrow_forwardChoose the statements that correctly describe the characteristics of the stars located in the labeled quadrants of the H-R diagram. Luminosityarrow_forwarda) The star 58 Eridani is a feint but naked-eye star similar to the Sun. Suppose that you are observing this star in the night sky without a telescope. Ignoring any interstellar extinction or atmospheric absorption, approximately how many photons per second arrive at your retina? Show all steps in your calculation. Look up any required information about the star using Wikipedia. Use sensible approximations so your calculation is straightforward. For example you could consider only the region of the spectrum where the photon flux peaks. b) The Mid-Infrared Instrument (MIRI, camera and spectrograph) on the James Webb Space Telescope operates in the band 5 – 28 µm. For 58 Eridani, approximately how many photons per second can be used by this instrument? Assume that MIRI takes all the photons from the full JWST mirror. Show all steps in your calculation. Describe briefly two or three other factors which play a role in determining the sensitivity of an instrument such as MIRI?arrow_forwardConsider two stars, A and B, of equal size. You take a spectrum of each star and findthat the flux of star A peaks at a wavelength of 9000 ̊ A and the flux of star B peaksat 3000 ̊ A. What is the relative luminosities of the two stars? Which star is the hotterone? If star A is at a distance of 10 pc, what distance would star B have to be inorder for both stars to appear equally bright as viewed from Earth?arrow_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_forwardAs a star runs out of hydrogen to fuel nuclear fusion in its core, changes within the star usually cause it to leave the main sequence, expanding and cooling as it does so. Would a star with a radius 12 times that of the Sun, but a surface temperature 0.5 times that of the Sun, be more, or less luminous than the Sun? Show and explain your reasoning. You may assume the surface area of a sphere is A = 4πr2.arrow_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_forwardAstronomers us the P-Cygni line features in a spectrum of a supernova to... Select one alternative: ...measure the velocity of the supernova ejecta. ...to measure the rotation speed of the star that exploded. ...measure the composition of the supernova ejecta more accurately than with other lines. ...to measure the mass of the neutron star or black hole formed in the supernova.arrow_forwardlambdamax = 600nm (5000K/T) L ∝ R2 T 4 1. What is the peak wavelength of an O star of temperature 50,000 K? What range of the spectrum is this?arrow_forwardarrow_back_iosSEE MORE QUESTIONSarrow_forward_ios
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