Post Main Sequence

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  1. A nova is a sudden brightening of a star that occurs when
    material from a companion star is transferred onto the surface of a white dwarfin a binary system and is subsequently blasted into space by a runaway thermonuclearexplosion, leaving the white dwarf intact to repeat the process.
  2. In terms of nuclear reactions, what is the next stage of a star's life after theend of hydrogen burning in the core?
    hydrogen burning in a thin shell around the core
  3. At which phase of its evolutionary life is a white dwarf star?
    very late for a small mass star, the dying phase
  4. Observations of the spectrum of the solar corona reveal emission lines that comefrom atoms from which many electrons have been stripped. What conclusion can bedrawn from this result?
    The gas temperatures are extremely high.
  5. What happens to the surface of a low-mass star after the helium core and heliumshell nuclear fusion "burning" stages are completed?
    It is propelled slowly away from the core to form a planetary nebula.
  6. In some binary star systems, such as Algol, the less massive star is a red giantand the more massive star is on the main sequence. This is evidence that
    mass transfer has occurred from one star to another.
  7. A white dwarf star, as it evolves, undergoes which of the following changes?
    Luminosity and temperature decrease, but its size remains constant.
  8. What is the most important quantity on which the lifetime of a star depends?
    mass of the star
  9. At what stage of evolution are the horizontal-branch stars, which have similarluminosities between 50 and 100 times that of the Sun but a range of temperatures?
    post–main-sequence stage
  10. The helium flash is another name for
    a sudden onset of helium fusion reactions in the core of a low-mass red giantstar.
  11. Which stage in a low mass star's life will life on the surface of the Earth beextinguished?
    red giant
  12. At what stage of its evolutionary life is the Sun?
    main sequence—middle age
  13. Compared to the composition of the early Sun, the composition of the gas in thecore of a red giant star is
    significantly different, with a very high fraction of He and no H.
  14. What is the last nuclear burning stage in the life of a low-mass star like theSun?
    fusion of helium nuclei to form carbon
  15. A white dwarf is
    a low-mass star at the end of its life.

Card Set Information

Post Main Sequence
2012-04-28 21:13:10
Astro1 Exam2

post main sequence
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