Here's why:

* Spectral Type: Etamin is a giant star classified as a K5 giant.

* Luminosity: K5 giants are considerably more luminous than our Sun. Etamin's luminosity is estimated to be around 1000 times that of the Sun.

* Temperature: While K-type stars are cooler than our Sun, their high luminosity indicates that they are much larger and have significantly higher mass.

Therefore, Etamin is classified as a high-mass star.