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Science

Q: A parsec is slightly more than 200,000 AU.
Q: A parsec is about 3.3 light-years.
Q: Every solar type star ever formed still shines in the Milky Way Galaxy, yet our naked eyes see stars that generally are much younger than the Sun. Explain.
Q: Describe the various ways that stellar masses can be determined in binary star systems.
Q: What special type of information is yielded only by eclipsing binary stars?
Q: Why are eclipsing binaries the rarest of the three types discussed?
Q: Compare and contrast stars on the upper left and lower right of the main sequence.
Q: Where do the majority of naked-eye stars fall on the H-R diagram? Is this true of the majority of stars close to our Sun as well?
Q: What two properties of the stars were Hertzsprung and Russell comparing?
Q: Why do the spectra of stars differ, if they are all chiefly hydrogen and helium?
Q: Contrast apparent and absolute magnitudes.
Q: Explain the difference between radial and transverse velocities.
Q: How did the Hipparcos mission revolutionize our knowledge of stellar properties?
Q: Must we see both spectral lines splitting to find a spectroscopic binary?
Q: Why don't stars less massive then type M exist?
Q: What is the relationship between a star's mass and its lifetime?
Q: Contrast finding the distances to seventh magnitude M3V and M3Ib stars.
Q: What color are most of the stars closest to the Sun?
Q: Why is the main sequence main? Why are these stars so common?
Q: Contrast main sequence stars of type B and G.
Q: What percentage of stars lie on the main sequence? Why?
Q: How can a white dwarf be hotter than our Sun, yet much less luminous?
Q: Discuss the mass, temperature, color and size of an M3V star, compared to the Sun.
Q: Why can the Hubble Space Telescope give us better direct measurements of star diameters than larger Earth-based telescopes can?
Q: How does a star's luminosity relate to its radius and surface temperature?
Q: How can Betelgeuse be only half the Sun's surface temperature, yet about 10,000 times more luminous than the hotter Sun?
Q: Why is it difficult to directly measure the size of a star's disk from Earth?
Q: Why is hydrogen less obvious in B stars than in A class?
Q: What role do molecules play in spectral classification?
Q: What role does hydrogen play in spectral classification?
Q: What role does helium play in spectral classification?
Q: The apparent magnitude of the Sun is -26, while Sirius has an apparent magnitude of -1; how much brighter does the Sun appear than Sirius?
Q: Describe the distance and composition of the Alpha Centauri system.
Q: Which star has the largest proper motion? Why?
Q: Why must both parallax and proper motion be known to give transverse velocity?
Q: How is proper motion measured?
Q: In general, as you examine stars on the main sequence, going from bottom right to top left, their stellar radii ________.
Q: The type of binaries where we can find their sizes have their orbits almost ________ as seen from the Earth.
Q: High mass stars are typically found on the ________ of the main sequence.
Q: In general, the more massive the star, the ________ its lifetime.
Q: A star system where we observe the magnitude to increase and decrease is an ________.
Q: If a binary is detected by periodic shifts in its spectral lines, it is a ________ binary.
Q: The star's ________ plays the major role in determining its main sequence position and luminosity.
Q: Stellar masses are determined by observing ________ stars.
Q: Contrasting a M3Ib and M3V star, they differ primarily in ________ and ________.
Q: The largest supergiants, like Deneb and Rigel, are luminosity class ________.
Q: A star's ________ parallax is found by using the spectral lines to estimate the spectral class and luminosity of distant stars.
Q: The complete spectral classification of our Sun is ________.
Q: White dwarfs like Sirius B are typically the size of ________.
Q: Where on the H-R diagram are the majority of stars that dominate the night sky?
Q: Stars of the main sequence, like our own, are all converting ________ into helium.
Q: If a G2 star is 100 times as luminous as our Sun, it must be ________ times the Sun's diameter.
Q: At spectral type B1, Spica is about three times hotter than the Sun, so every square cm. of Spica must give off ________ times more energy than our Sun does.
Q: A star both twice the diameter and twice the temperature of our Sun would be ________ times more luminous than our Sun; in fact, Vega fits this description well.
Q: Arcturus, the brightest star of spring skies, is spectral type K, so to us it appears ________ in color.
Q: Only type O stars are hot enough to show ionized ________ in their spectra.
Q: The strongest lines present in spectral class A stars are absorption lines of ________.
Q: In the M class stars, we find ________ absorption lines not seen in hotter stars.
Q: The ionized helium lines show up only in class ________ stars.
Q: From hottest to coolest, the seven letters for the star types are ________.
Q: The main difference between an A2V and F2V star is their ________.
Q: Two stars are both spectral type K2V; if the closer is magnitude +3.7, and the fainter is magnitude +8.7, then the brighter star is about ________ times closer.
Q: A star with an apparent magnitude of +2.3 and an absolute magnitude of +5.9 lies ________ than 10 parsecs away.
Q: The absolute magnitude of a star is how bright it appears if viewed from a distance of ________ light-years.
Q: The ________ magnitude of a star depends on its luminosity and distance from us.
Q: The absolute magnitude of the Sun is ________.
Q: If two stars have the same parallax, but the brighter is magnitude +2.3, and the fainter is magnitude +3.3, then the fainter star is ________ less luminous.
Q: The absolute magnitude scale is defined so that a difference of five magnitudes is a luminosity difference of ________.
Q: If a star has a parallax of .005", then its distance is ________ light-years.
Q: To find the ________ velocity, we must combine proper motion and parallax data.
Q: The distance to a star with a parallax angle of 0.2 arc seconds is ________.
Q: Studies of a star's position made on the same calendar date over subsequent years yield ________.
Q: A stars total velocity is a combination of its ________ and ________ velocities.
Q: If its parallax is 1", then the distance to the star is ________ light-years.
Q: To find the distance of nearby stars, we use their parallaxes obtained over ________-month intervals.
Q: In addition to the proper motion, we also need the ________ to find the transverse velocity of a star across our line of sight.
Q: What information can be gained from the light curves of eclipsing binaries? A) their distances B) their masses C) their sizes D) their temperatures E) their luminosities
Q: In what range of masses are most stars found? A) 0.1 to 2 solar masses B) 1 to 3 solar masses C) 0.1 to 100 solar masses D) 0.01 to 100 solar masses E) Stars can have any mass.
Q: Stellar masses are measured directly by observations of the motions of A) eclipsing binary systems. B) spectroscopic binary systems. C) visual binary systems. D) All of the above can give us their masses. E) Stellar masses cannot be measured directly by any method.
Q: If we know the average separation and period of revolution for a binary system, we can then measure A) the actual sizes of the two stars. B) the total mass of the system. C) their absolute magnitudes. D) the actual mass of both individual stars. E) the actual luminosity of each star.
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