Rho Scorpii

Rho Scorpii
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 15h 56m 53.07624s[1]
Declination −29° 12 50.6612 [1]
Apparent magnitude (V) 3.86[2]
Spectral type B2 IV[3]
U−B color index -0.82[2]
B−V color index -0.20[2]
Radial velocity (Rv)−0.40[4] km/s
Proper motion (μ) RA: −15.68[1] mas/yr
Dec.: −24.88[1] mas/yr
Parallax (π)6.91 ± 0.19[1] mas
Distance470 ± 10 ly
(145 ± 4 pc)
Period (P)4.0033 d
Eccentricity (e)0.27
Periastron epoch (T)2442178.6060 JD
Argument of periastron (ω)
Semi-amplitude (K1)
16.40 km/s
Mass7.94±0.55[3] M
Radius5.0[6] R
Luminosity (bolometric)3,432[3] L
Temperature21,150[3] K
Rotational velocity (v sin i)113[7] km/s
Other designations
5 Scorpii, ADS 9846, CCDM J15569-2913A, FK5 3258, GC 21398, HD 142669, HIP 78104, HR 5928, SAO 183957.[8]

Rho Scorpii (ρ Sco, ρ Scorpii) is a binary star in the constellation Scorpius. It has an apparent visual magnitude of +3.87, which is bright enough to be seen with the naked eye. Based upon parallax measurements, it is located approximately 472 light years from the Sun.[1] At that distance, the visual magnitude of the star is reduced by 0.07 due to extinction from interstellar dust.[9]

The primary component A is a single-lined spectroscopic binary with an orbital period of 4 days and an eccentricity of 0.27.[5] This pair displays the spectrum of blue-white B-type subgiant with a stellar classification of B2 IV.[3] It has an estimated mass nearly 8 times that of the Sun and shines with 3,432 times the Sun's luminosity.[3] A third star, component B, is a magnitude 12.80 visual companion that lies at an angular separation of 38.40 arcseconds along a position angle of 95°, as of the year 2000.[10]

Rho Scorpii is a member of the Upper Scorpius OB association.[11]


  1. 1 2 3 4 5 6 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. 1 2 3 Ducati, J. R. (2002), "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system", CDS/ADC Collection of Electronic Catalogues, 2237, Bibcode:2002yCat.2237....0D.
  3. 1 2 3 4 5 6 Hohle, M. M.; et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335Freely accessible, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355.
  4. Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E.
  5. 1 2 Pourbaix, D.; et al. (September 2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics, 424: 727–732, arXiv:astro-ph/0406573Freely accessible, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213.
  6. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 521–524, arXiv:astro-ph/0012289Freely accessible, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  7. Simón-Díaz, S.; Herrero, A. (2014), "The IACOB project: I. Rotational velocities in northern Galactic O- and early B-type stars revisited. The impact of other sources of line-broadening", Astronomy & Astrophysics, 562: A135, arXiv:1311.3360Freely accessible, Bibcode:2014A&A...562A.135S, doi:10.1051/0004-6361/201322758.
  8. "rho Sco -- Spectroscopic binary", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-09-22.
  9. Shatsky, N.; Tokovinin, A. (January 2002), "The mass ratio distribution of B-type visual binaries in the Sco OB2 association", Astronomy and Astrophysics, 382: 92–103, arXiv:astro-ph/0109456Freely accessible, Bibcode:2002A&A...382...92S, doi:10.1051/0004-6361:20011542.
  10. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
  11. Grellmann, R.; et al. (June 2015), "New constraints on the multiplicity of massive young stars in Upper Scorpius", Astronomy & Astrophysics, 578: 11, Bibcode:2015A&A...578A..84G, doi:10.1051/0004-6361/201219577, A84.
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