Answer:
Rank of the stars from shortest to longest distances:
Barnard's Star (M4)
61 Cygnia A (K5)
Alpha Centauri A (G2)
Sirius (A1)
Spica (B1)
Explanation:
The habitable zone, also known as the circumstellar habitable zone, is the range of distances from a star where it is not too hot and not too cold for liquid water to exist on the surface of surrounding planets.
The location of a star’s habitable zone is dependent upon its luminosity, which is the amount of light emitted by an object in a unit of time, because a star’s luminosity increases with time; and also the star's mass.
The inverse square law of light brightness can be used to determine the extent of the habitable zones for different luminosity stars with the formula:
star boundary = Sun boundary × squareroot[(star luminosity)/(Sun luminosity].
