Considering both longevity and luminosity, which of these stars ...

[HCHenry]

Considering both longevity and luminosity, which of these stars would be the most likely candidate for seeking extraterrestrial intelligence?
 
  A) Spica, a B3 main-sequence star
  B) Sirius B, a white dwarf
  C) Antares, a M3 supergiant
  D) 61 Cygni, a K2 main-sequence star
  E) Barnard's star, a M5 dwarf

Question 2

Why is M-42, the Orion Nebula, so important to us?
 
  What will be an ideal response?

[juliaf]

Answer to Question 1

D

Answer to Question 2

It is the closest and brightest region of active star formation visible to most of the astronomers of the world. It is bright enough to be seen with the naked eye, and a cinch to find just below the belt of Orion. We can detect young protostars still hiding behind their cocoons of dust with infrared telescopes, and watch their T-Tauri winds blow away the dust and reveal the young stars stabilizing on the main sequence. Many of the protostars show dusty disks, suggesting that planet formation is routine, and some brown dwarfs are also evident, still hot from gravitational contraction.