Antares is a class M supergiant star, with a diameter of approximately 1.33 * 10 ^9 km, or if in place of our sun, it would slightly more than encompass the average orbit of Jupiter, and is approximately 600 light years from earth. Visually, its luminosity is about 10,000 times that of the Sun but overall, taking into account that the star radiates a considerable part of its energy in the infrared part of the spectrum the luminosity equals roughly 65,000 times that of the Sun. The mass of the star is calculated to be 15 to 18 solar masses. Its large size and relatively small mass give Antares a very low density.
Т.е. очень большая но очень легкая ("всего" в 18 раз тяжелее солнца) звезда.