1. More massive stars have, compared to our Sun, a) shorter lifetimes b) a large
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1. More massive stars have, compared to our Sun, a) shorter lifetimes b) a larger rate of H to He fusion c) hotter surface and core temperatures d) all of the above 2. Two stars have the same radius but star A has a surface temperature of 5000 degrees K while star B has a surface temperature of 15, 000 degrees K. Star B will have a) more electromagnetic radiation in the UV than star A always have a larger absolute luminosity than star c) sometimes have a smaller and sometime have a larger apparent luminosity than star d) all of the above 3. The gravitational pull in the centers of highly evolved Red Giants is resisted by the pressure due to a) the weak nuclear force b) helium atoms c) the interstellar medium d) degenerate electronsExplanation / Answer
1)a) Shorter life time.
the life time of a star depends on its mass (amount of fuel) and the rate at which this fuel burns, as the mass of the star increases the gravitational force inside become stronger and which rises the temperature with in the star leads to rapid burning of this fuel, hence the life time become short.
2)d) All the above.
according to the relation between temperature and flux emitted by the star, flux is proportional to fourth power of temperature. so high surface temperature star emit large flux in all wavelength, and the luminosity also increases with the surface temperature.
3)degenerate electrons
the electron degeneracy pressure prevents such star from collaps under gravitational field. matter in this conditions are highly denser and it oppose the gravitational force in addition to the thermal pressure.
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