Which is used observationally to determine the age of a star ...

[CORALGRILL2014]

Which is used observationally to determine the age of a star cluster?
 
  A) the total number of main-sequence stars
  B) the luminosity of the main-sequence turn-off point
  C) the amount of dust that lies around the cluster
  D) the number of white dwarfs
  E) the ratio of giants to supergiants

Question 2

Which of the following are the best candidates to search for planets that might harbor extraterrestrial life?
 
  A) low mass stars (less than one-tenth of the mass of the Sun), because these are the most common stars in our galaxy
  B) solar-mass stars, because they have both a large habitable zone and a long stellar lifetime.
  C) massive stars (greater than twice the mass of the Sun) because they provide more energy to promote biology
  D) halo stars, because planets can form in isolation from disruptive stellar encounters
  E) binary stars, because they provide twice as much energy to promote biology

[kaykay69]

Answer to Question 1

B

Answer to Question 2

B

[CORALGRILL2014]

Great answer, keep it coming

[helenmarkerine]

Gracias!