Omicron Lupi

Omicron Lupi (ο Lup) is a binary star^[3] in the southern constellation of Lupus. It is a visible to the naked eye with a combined apparent visual magnitude of 4.323.^[2] Based upon an annual parallax shift of 8.07 mas as seen from Earth,^[1] it is located around 400 light-years from the Sun, give or take 30 light-years. At that distance, the visual magnitude of the system is diminished by an extinction factor of 0.13±0.01 due to interstellar dust.^[5] It is a member of the Upper Centaurus–Lupus^[8] subgroup of the nearby Scorpius–Centaurus association.^[6]

Omicron Lupi

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Lupus
Right ascension	14h 51m 38.30289s[1]
Declination	−43° 34′ 31.2965″[1]
Apparent magnitude (V)	4.323[2] (4.84 + 5.27)[3]
Characteristics
Spectral type	B5 IV[3]
U−B color index	−0.620[2]
B−V color index	−0.159[2]
Astrometry
Radial velocity (Rv)	+7.30±0.74[4] km/s
Proper motion (μ)	RA: −25.20[1] mas/yr Dec.: −27.13[1] mas/yr
Parallax (π)	8.07 ± 0.59 mas[1]
Distance	400 ± 30 ly (124 ± 9 pc)
Absolute magnitude (MV)	−1.2±0.3[5]
Details
Mass	5.7±0.2[5] M☉
Radius	3.5[5] R☉
Luminosity	1,260[5] L☉
Surface gravity (log g)	4.1±0.1[5] cgs
Temperature	18,000[6] K
Rotational velocity (v sin i)	25[6] km/s
Other designations
ο Lup, CD−43° 9391, HD 130807, HIP 72683, HR 5528, SAO 225248.[7]
Database references
SIMBAD	data

This is a visual binary star system with the components having an angular separation of 0.1 arcsecond.^[8] The primary, component A, is a magnitude 4.84 B-type subgiant star with a stellar classification of B5 V.^[3] It displays radial velocity variations indicating it has an unseen second companion orbiting at a separation of at least 17 AU with a period of 27 years or more.^[6] The spectrum of the primary displays a Zeeman effect indicating a magnetic field with a strength ranging from −94 to 677 G.^[6] The visible companion, component B, has a visual magnitude of 5.27.^[3]

References

1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
2. Cousins, A. W. J. (1973), "Revised zero points and UBV photometry of stars in the Harvard E and F regions", Memoirs of the Royal Astronomical Society, 77: 223–236, Bibcode:1973MmRAS..77..223C.
3. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
4. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
5. Petit, V.; et al. (February 2013), "A magnetic confinement versus rotation classification of massive-star magnetospheres" (PDF), Monthly Notices of the Royal Astronomical Society, 429 (1): 398–422, arXiv:1211.0282, Bibcode:2013MNRAS.429..398P, doi:10.1093/mnras/sts344.
6. Alecian, E.; et al. (December 2011), "First HARPSpol discoveries of magnetic fields in massive stars", Astronomy & Astrophysics, 536: 4, arXiv:1111.3433, Bibcode:2011A&A...536L...6A, doi:10.1051/0004-6361/201118354, S2CID 51173988, L6.
7. "omi Lup". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-03-10.
8. Chen, Christine H.; et al. (September 2012), "A Spitzer MIPS Study of 2.5-2.0 M_⊙ Stars in Scorpius–Centaurus", The Astrophysical Journal, 756 (2): 24, arXiv:1207.3415, Bibcode:2012ApJ...756..133C, doi:10.1088/0004-637X/756/2/133, S2CID 119278056, 133.