Astronomy 1.Why do you suppose that O stars exhibit weak hydrogen absorption lin

Question

Astronomy

1.Why do you suppose that O stars exhibit weak hydrogen absorption lines?
      
A.O stars are too cool to excite hydrogen atoms to the first energy level from which they can then absorb visible wavelengths of light.
      
B.O stars contain very little hydrogen.
      
C.At these high temperatures, nearly all the hydrogen is ionized, and is therefore unable to interact with light.

2.Which most closely approximates the mass of a white dwarf?
      
A.the Sun
      
B.the Earth
      
C.the Moon
      
D.Jupiter

Explanation / Answer

1)ANSWER: A

EXPLANATION: O star is ahot bule white star.temperature is excess of 30,000 kelvin to 52,000kelvin.It emitts ultra violet rays.Due to the high temperatures all the hydrogen is ionized

2)ANSWER: A

EXPLANATION: White dwarf also called degeneratev dwarf composed mostly of electron degenerate matter.A white dwarf faint luminosity comes from the emmision of stored thermal energy,no fusion takes place in white dwarf where in mass converted to energy

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