Question

Which of the following stars is the coolest?

Sirius, a type A star
Arcturus, a type K star
Spica, a type B star
Antares, a type M star

Answer 1

Antares, a type M star

Step-by-step explanation:

Stars are classified based in temperature using alphabets:

O, B, A, F, G, K, and M

Where, O represents a star having very high temperature. It would also be blue in color. (temperature about 41,000 K)

M represents a cool star having low temperature and red in color. (temperature about 3850 K)

Thus, Antares which is classified as a type M star would be the coolest.

Answer 2

A star is a sphere composed of hydrogen and plasma. Red dwarfs are the coolest stars , also called M type of stars. (The solution is Antares, a type M star). These cool stars are small stars in therms of their mass and have not enough mass to produce energy. That is the reason why they are the coolest.