are wider than the lines from stars because the gas is hotter than most stars.
are more narrow than the lines from stars because the gas has a lower pressure than stars.
indicate that the interstellar medium contains dust.
indicate that the interstellar medium is expanding away from the sun.
none of the above
____ 21. Extinction by the interstellar medium dims starlight by about 2 magnitudes for every 1000 pc the light travels. What fraction of the photons remain from a star that is 5000 pc from an observer?
____ 22. Which of the following have been suggested as explanations of the missing solar neutrinos?
The sun is fusing helium but not hydrogen.
Nuclear reactions do not produce neutrinos as fast as theory predicts.
The sun may contain WIMPs.
Neutrinos may oscillate between three different flavors.
III & IV
II, III, & IV
I, II, & IV
____ 23. _____________ are small luminous nebulae excited by nearby young stars.
____ 24. The region of the sun just below the photosphere
is undergoing thermonuclear fusion using the proton-proton chain.
is undergoing thermonuclear fusion using the CNO cycle.
is transporting energy to the photosphere by convection.
is not in hydrostatic equilibrium.
a and c above
____ 25. The diagram below is an HR diagram. The line indicates the location of the main sequence. Which of the five labeled locations on the HR diagram indicates a luminosity and temperature similar to that of a T Tauri star.
____ 26. If the sun produces energy by the proton-proton chain, then the center of the sun must have a temperature of at least
the result of the collapse of the iron core of each star.
nebulae associated with Herbig-Haro objects.
____ 36. When material expanding away from a star in a binary system reaches the Roche surface
the material will start to fall back toward the star.
all of the material will accrete on to the companion.
the material is no longer gravitationally bound to the star.
the material will increase in temperature an eventually undergo thermonuclear fusion.
c and d
____ 37. The diagram below shows a light curve from a supernova. How many days after maximum light did it take for the supernova to decrease in brightness by a factor of 100?
____ 38. A supernova remnant is expanding in radius at the rate of 0.5 seconds of arc per year. Doppler shifts show that the velocity of expansion is 5700 km/sec. How far away is the supernova remnant?
____ 39. The peculiar system SS 433
is emitting beams of energy and matter.
is producing a spectrum with both a red and a blue shift
probably contains an accretion disk.
is the result of a planetary nebula.
II & III
I, II, & III
I, II, III, & IV
____ 40. Millisecond pulsars that are very old are
believed to be the result of mass transfer from a companion that increases the mass of the pulsar.
all single objects.
not spinning as rapidly they seem because they have four hot spots that produce the flashes.
Complete each sentence or statement.
41. The parallax of the star 75 Leo is 0.10 and its apparent visual magnitude is +5.18. The absolute visual magnitude of 75 Leo is ____________.
42. Luminosity class IV objects are known as __________________.
43. On the HR diagram below, indicate the location of the white dwarf stars.
44. Molecules emit radiation at _____________ wavelengths.
45. __________ appear reddish in color due to the light emitted by the Balmer series of the hydrogen atom.
46. The ______________ is the thermonuclear fusion of helium to form carbon.
47. A gas in which the pressure no longer depends on the temperature of the gas is said to be _____________.
48. A(n) __________ is the sudden expulsion of the outer layers of a moderate mass star that has a dormant carbon core.
49. Electrons moving in a strong magnetic field emit _________________ radiation.
50. Material within the ____________ of a rotating black hole is forced to orbit the black hole due to the curvature of space-time, but could still escape the gravitational pull of the black hole.
51. If the sun and stars are supported by gas pressure, what supports a neutron star?
52. Why does our theory predict that neutron stars will have strong magnetic fields?
43. An elongated region should be indicated that stretches from a luminosity of about 10-2 and spectral type B to luminosity of about 10-4 and spectral type G. (See Figures 9-8 and 9-9 in the text).