Question

30. Why are the Balmer lines in the spectra of giant stars narrower than those for main-sequence stars?

31. Binary stars are [common, very rare].

32. Binary stars allow us to determine what very important property of stars?

33. In a binary system the center of mass lies closer to the [more massive, less massive] star.

34. What type of star is Sirius B? [main sequence, white dwarf, giant]

35. Why does a spectroscopic binary system only allow us to find a lower limit to the masses of the stars?

36. It takes about how many hours for the stars of Algol to revolve?

37. [Giants, White dwarfs, Main sequence stars] best obey the mass-luminosity relation.

38. Which has the higher average density, supergiants or main-sequence stars?

39. The sun converts how many million tons of mass intro energy each second?

40. Three types of binary systems are called visual, spectroscopic, and what?

Answer 1

Q30)Balmer lines are due to atmospheric density .main sequence stars are most dense so they have widelines whereas faint stars have narrower lines because it's less dense then main sequence ones and supergaints have most narrow as they are least dense then both .

Q31)They are common.More than four-fifths of the single points of light we observe in the night sky are actually two or more stars orbiting together. The most common of the multiple star systems are binary stars, systems of only two stars together.

Q32) Binary star systems provide the best means for scientists to determine the mass of a star. As the pair pulls on each other, astronomers can calculate the size, and from there determine characteristics such as temperature and radius.

Q33)If they have different masses, the center of mass is always found closer to the more massive object.

**According to the HOMEWORKLIB RULES I should have done only first question in case of multiple questions.here I have done 4 but next time I wouldn't be able to do so .

Please mark tha required one or upload them separately.