13 Scorpii is a spectroscopic binary, meaning the two stars are too close to be individually resolved, but periodic Doppler shifts in the star's spectrum indicate there must be orbital motion. In this case, light from only one of its stars can be detected and it is a double-lined spectroscopic binary.[3] The two have an orbital period of 5.7805 days and an eccentricity of 0.19.[3] The primary star, at 11 million years old,[6] is a B-type main-sequence star with a spectral type of B2V.[3] While the primary's mass is estimated to be about 7.8 M☉, its companion is thought to have a mass of 1.12 M☉.[6]
^ abHøg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
^ abJohnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
^Evans, D. S. (1967). "The Revision of the General Catalogue of Radial Velocities". In Alan Henry Batten; John Frederick Heard (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 held at the University of Toronto 20-24 June, 1966. International Astronomical Union. Vol. 30. London: Academic Press. p. 57. Bibcode:1967IAUS...30...57E.