Antares (α Scorpii, Alpha Scorpii) is a red supergiant star in the Milky Way galaxy and the sixteenth brightest star in the nighttime sky. It is listed as 15th or 16th brightest, depending on how the two brighter components of the Capella quadruple star system are counted.
Antares has a secondary, or companion star, Antares B. The orbit of the companion star and its properties are not properly known, with an estimated period of 1,200 to 2,562 years.
Antares has a radius of about 680 to 800 times that of the Sun. This gives Antares a diameter between 947 to 1.114 billion kilometers in size. If Antares was placed in the center of our solar system, its outer surface would lie between the orbits of Mars and Jupiter, in the asteroid belt. Antares is about 550 light-years (or 170 parsecs) from the Earth. Its visual luminosity is about 10,000 times that of the Sun. Because the star radiates much of its energy in the infrared part of the spectrum, the bolometric luminosity is about 65,000 times that of the Sun. The mass of the star is in the range of 15 to 18 solar masses.
Antares is one of the first red supergiants to be directly imaged.
- Pecaut, Mark J. et al 2012. A revised age for Upper Scorpius and the star formation history among the F-type members of the Scorpius-Centaurus OB Association. Astrophysical Journal 746 (2): 154 .
- Schaaf, Fred 2008. The brightest stars: discovering the Universe through the sky's most brilliant stars. Wiley. p. 218. ISBN 978-0-471-70410-2