Chapter 10 Questions and Answers 2024

Chapter 10 Questions and Answers 2024 The star Bernard's Star has an apparent magnitude of 9.5 and the star Lelande 21185 has an apparent magnitude of 7.5. Which one is brighter? By how many times? Lelande 21185 is the brighter star as the more negative the magnitude is, the brighter the object is. Subtract the two magnitudes and take the absolute value to get a positive answer. Then use that answer as the power on 2.512. |9.5-(+7.5)| =2| =2| 2.5 ^2 = 6.25 Therefore Lelande 21185 is about 6 times brighter than Bernard's Star. The star Rigel Kentaurus has an apparent magnitude of -0.01 and an absolute magnitude of 4.4. Is Rigel Kentaurus bright in our sky because it is intrinsically bright or because it is close to the Earth? The star Rigel Kentaurus is bright in our sky because it is "close" to our Solar System. (You can tell this by looking at the absolute magnitude, which is lower than the apparent magnitude.) Brainpower Read More Previous Play Next Rewind 10 seconds Move forward 10 seconds Unmute 0:00 / 0:15 Full screen The star Spica has an apparent magnitude of 1.04 and an absolute magnitude of 3.55. Is Spica bright in our sky because it is intrinsically luminous or is it bright because it is close to the Earth? The star Spica is bright because it is intrinsically luminous (its absolute magnitude is higher than its apparent magnitude). What are the two factors that determine the luminosity of a star? The luminosity of a star is determined by its mass (determines temperature and amount of energy emitted) and its size (how large of a surface area is emitting light). What quantities does the Hertzsprung-Russell diagram relate? The Hertzsprung-Russell diagram relates luminosity (or absolute magnitude) on the vertical axis to the spectral class (or temperature) on the horizontal axis. In what group are most of the stars located? Most of the stars are located in the main sequence. The star Capella has roughly the same surface temperature as the Sun, but has a luminosity about 100 times greater than the Sun. Which star is larger? Capella must be larger in order to have the same surface temperature as our Sun but emitting more energy than our Sun. Regulus and Capella have the same luminosities, but Regulus has a surface temperature of 15,000 K while Capella's surface temperature is about 5500 K. Which star is larger? Capella must be larger because it is cooler (and emitting less energy per square mile) than Regulus so must have a larger surface area to emit as much energy as Regulus. Which is hotter, a B spectral class star or an F spectral class star? The B spectral class stars are hotter than the F spectral class stars. How are continuous, emission, and absorption spectra formed? When light is passed through a prism or diffraction grating: (1) a continuous spectrum is formed when light is being emitting from a hot, dense gas or a hot solid, (2) an emission spectrum is formed when light is being emitting from a hot, very low-density gas, (3) an absorption spectrum is formed when light that is being emitting from a hot, dense gas passes through a cooler gas. Stars generally have a(n) ____spectrum. A. absorption or an emission B. continuous C. emission D. absorption D. absorption The spectrum of a star provides information on ___. A. the radial motion of the star B. the surface composition of the star C. the surface temperature of the star D. only choices (a) and (b) E. choices (a), (b), and (c) E. choices (a), (b), and (c) We can find the distance to a star if we know its ___. A. mass B. apparent magnitude C. surface temperature D. parallax angle D. parallax angle The luminosity class of a star is related to its ___. A. temperature B. distance C. radius D. mass C. radius Applying Kepler's third law to a binary star system allows us to determine ____. A. the system's apparent magnitude B. the system's total mass C. the system's distance from Earth D. the mass of each star B. the system's total mass Stars A and B have the same temperature, but star A is more luminous than star B. Star A must be ___. A. hotter B. further away C. less massive D. smaller in radius E. larger in radius E. larger in radius In the Hertzsprung-Russell diagram, the main sequence extends from ___. A. high luminosity, high temperature to low luminosity, low temperature B. high luminosity, low temperature to low luminosity, high temperature C. high luminosity, low temperature to low luminosity, low temperature D. high luminosity, high temperature to low luminosity, high temperature A. high luminosity, high temperature to low luminosity, low temperature A star that is very luminous but has a low surface temperature must ____. A. be very massive B. have a very large diameter C. be very distant D. have a dim companion star B. have a very large diameter Stars that have the largest radii are classified as ___. A. upper main sequence B. ultragiants C. supergiants D. giants C. supergiants Which of the following spectral classes is the hottest? A. M B. K C. G D. B D. B The luminosity of a star depends on ___. A. the amount of energy it emits per second (power) B. its distance C. its Doppler shift A. the amount of energy it emits per second (power)