A group of graduate students, bored during a cloudy night at a the observatory, begin to make bets about the time different stars will take to evolve. If they have a cluster of stars which were all born roughly the same time, and want to know which star will become a red giant first, which of the following stars should they bet on? a. a star that would type O on the main sequence star b. a star about 1/2 the mass of our sun  c. a star about 8% the mass of our sun d. all stars reach the red giant stage in roughly the same number of years

Based on what you learned about stellar evolution, select all of the correct statements from the following list.   1. The period of some Cepheid variables actually changes. 2. When getting dimmer, variable stars are releasing energy; when getting brighter they are storing energy. 3. variable stars are expanding and contracting 4. despite their variability, variable stars stay in a specific position on the H-R diagram. 5. A changing period in a Cepheid variable means that the size of the star is changing and that the star is therefore evolving. 6. Only stars on the instability strip are variable. 7. More massive stars will vary their brightness more quickly.

Astronomers 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.

Place the following events in the formation of stars in the proper chronological sequence, with the oldest first and the youngest last. w. the gas and dust in the nebula flatten to a disk shape due to gravity and a steadily increasing rate of angular rotation x. a star emerges when the mass is great enough and the temperature is high enough to trigger thermonuclear fusion in the core y. the rotation of the nebular cloud increases as gas and dust concentrates by gravity within the growing protostar in the center z. some force, perhaps from a nearby supernova, imparts a rotation to a nebular cloud y, then z, then w, then x z, then y, then w, then x w, then y, then z, then x z, then x, then w, then y x, then z, then y, then w MacBook Air on .H. O O O O

Stars are born in   a. reflection nebulae.   b. dense molecular clouds.   c. HII regions.   d. the intercloud medium.   e. the local bubble.

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Indicate whether the following statements are true or false (Select T-True, F-False. If the first is T and the rest are F, enter TFFFF) A) A planetary nebula forms when a star violently explodes. B) White dwarfs are composed mostly of hydrogen. C) A white dwarf is the remnant of the star's core visible after the outer layers have been ejected. D) A planetary nebula is the remnant of the outer envelope of a star. E) White dwarfs are small dense objects about the size of the Earth.

Give ALL correct answers referring to the properties of known stars, i.e., B, AC, BCD... A) On the main sequence, more massive stars are colder. B) High mass stars are the most numerous type of stars observed in the galaxy. C) Giants are colder than main sequence stars at the same luminosity. D) Giants are brighter than dwarfs at the same temperature. E) On the main sequence, more massive stars are dimmer. F) White dwarf stars are much denser than main sequence stars. Hint: White dwarf stars have about the mass of our sun, but are only the size of the Earth. Therefore, they have a very high density.