Process of Science: Astronomers have not found any stars without ...

[KWilfred]

Process of Science: Astronomers have not found any stars without some heavy elements. How does this constrain theories for the formation of the first generation of stars in the Universe?
 
  What will be an ideal response?

Question 2

Define absorption lines.
 
  What will be an ideal response?

[Perkypinki]

Answer to Question 1

The first stars that formed must have lifetimes that are less than the present age of the Universe. This means that their masses were higher than the average mass of stars that form today.

Answer to Question 2

When light from a continuous source, such as the dense photosphere of a star, is passed though a thin, cool gas, certain energies from the continuum are absorbed, depending on which elements are present, creating a pattern of dark lines which identify the elements and molecules present in the cool gas cloud.

[KWilfred]

YES! Correct, THANKS for helping me on my review

[abro1885]

Excellent