Iota1 Scorpii

Iota1 Scorpii, Latinized from ι1 Scorpii, is a star in the southern constellation of Scorpius. With an apparent visual magnitude of 3.03, this star can be seen with the naked eye. It is sometimes called by the proper name Apollyon. Parallax measurements place it at a distance of roughly 1930 ly from Earth, with a 9% margin of error. At the estimated distance, the apparent magnitude is diminished by 0.66magnitudes due to interveining gas and dust between Earth and the star.

This star has a stellar classification of F2 Ia, with the 'Ia' luminosity class indicating this is a supergiant more luminous than typical supergiants. It has about 12 times the Sun's mass and is 35,000 times more luminous. The limb-darkened angular diameter of Iota1 Scorpii is estimated at $-6.51$. At the estimated distance, this corresponds to a physical radius of. The effective temperature of the photosphere is 6,910 or 7,103 K, which gives it a yellow-white hue typical of an F-type star.

Iota1 Scorpii has a 10th magnitude companion at an angular separation of 37.5 arcseconds, which, at the distance of this star, gives it a projected separation of 20,000 Astronomical Units (AU). As the relative separation of the two stars along the line of sight to the Earth is not known, however, this distance represents only a minimum value for their separation.