You observe a low-mass helium white dwarf. What can you conclude? ...

[londonang]

You observe a low-mass helium white dwarf. What can you conclude?
 
  A) It is over 100 billion years old.
  B) It will soon be a planetary nebula.
  C) It is part of a binary star system.
  D) Its core is mostly carbon.
  E) It was once a blue supergiant.

Question 2

The book discussed two different zones of habitability; describe and compare them.
 
  What will be an ideal response?

[fauacakatahaias]

Answer to Question 1

C

Answer to Question 2

For stars, their zones would lie close enough to the star for planets like Earth to have liquid water oceans, but not so close they would turn into Venus. For the Sun, this zone extends from the orbits of Venus out to Mars. The brighter the star, the larger this zone around it would extend. But the Galactic zone would be more related to the potential for an active nucleus to create so much energy in a quasar-like phase to wipe out life near it on the inside, and on the outside to the fact that at the outer edge of the disk, the rate of star formation (and planet formation as well) drops off greatly; for the Milky Way, this zone is probably about 10,000 to 50,000 light years from the center.

[londonang]

Gracias!

[nguyenhoanhat]

TYSM