Eta Lupi

η Lupi
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Lupus
Right ascension 16h 00m 07.32786s[1]
Declination −38° 23′ 48.1513″[1]
Apparent magnitude (V) 3.41[2] (3.37 + 7.50 + 10.85)[3]
Characteristics
Spectral type B2 IV + A5 Vp + F5 V[4]
U−B color index −0.83[2]
B−V color index −0.22[2]
Astrometry
Radial velocity (Rv)+1.00±3.80[5] km/s
Proper motion (μ) RA: −16.96[1] mas/yr
Dec.: −27.83[1] mas/yr
Parallax (π)7.38 ± 0.18[1] mas
Distance440 ± 10 ly
(136 ± 3 pc)
Details
η Lup A
Mass7.0±0.2[6] M☉
Radius6.7[7] R☉
Luminosity1,729[8] L☉
Temperature14,668[8] K
Rotational velocity (v sin i)242[9] km/s
Age39.8±9.2[6] Myr
Other designations
η Lup, CD−38° 10797, HD 143118, HIP 78384, HR 5948, SAO 207208.[10]
Database references
SIMBADdata

η Lupi, often Latinised as Eta Lupi, is a probable triple star[4][11] system in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 3.41.[2] Based upon an annual parallax shift of 27.80[1] mas as seen from Earth, it is located around 136 parsecs (440 ly) distant from the Sun. It is a member of the Upper Centaurus Lupus subgroup of the nearby Sco OB2 association.[12]

The inner pair in this triple system has an estimated orbital period of around 27,000 years.[11] As of 2013, they had an angular separation of 15.0 arc seconds along a position angle of 19°.[3] The primary star, component A, is an evolving A-type subgiant star with a stellar classification of B2 IV.[4] It has used up the supply of hydrogen at its core and has begun to expand off the main-sequence.

The secondary, component B, is a chemically peculiar A-type main sequence star with a class of A5 Vp[4] and an estimated mass 2.10 times that of the Sun.[11] The outer member, component C, has an orbital period of around half a million years.[11] As of 2007, it had an angular separation of 115.8 arc seconds along a position angle of 248° from the primary.[3] It is an F-type main sequence star with a classification of F5 V and an estimated 1.29 times the Sun's mass.[11]

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752 Freely accessible, doi:10.1051/0004-6361:20078357.
  2. 1 2 3 4 Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
  3. 1 2 3 Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22
  4. 1 2 3 4 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, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878 Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x.
  5. ↑ 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, Bibcode:2012A&A...546A..61D, arXiv:1208.3048 Freely accessible, doi:10.1051/0004-6361/201219219, A61.
  6. 1 2 Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, Bibcode:2011MNRAS.410..190T, arXiv:1007.4883 Freely accessible, doi:10.1111/j.1365-2966.2010.17434.x.
  7. ↑ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, Bibcode:2001A&A...367..521P, arXiv:astro-ph/0012289 Freely accessible, doi:10.1051/0004-6361:20000451.
  8. 1 2 McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037 Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x.
  9. ↑ Uesugi, Akira; Fukuda, Ichiro (1970), "Catalogue of rotational velocities of the stars", Contributions from the Institute of Astrophysics and Kwasan Observatory, University of Kyoto, Bibcode:1970crvs.book.....U
  10. ↑ "eta Lup -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-03-03.
  11. 1 2 3 4 5 Tokovinin, A. (2008), "Comparative statistics and origin of triple and quadruple stars", Monthly Notices of the Royal Astronomical Society, 389 (2): 925, Bibcode:2008MNRAS.389..925T, arXiv:0806.3263 Freely accessible, doi:10.1111/j.1365-2966.2008.13613.x.
  12. ↑ Kouwenhoven, M. B. N.; et al. (October 2007), "The primordial binary population. II. Recovering the binary population for intermediate mass stars in Scorpius OB2", Astronomy and Astrophysics, 474 (1): 77–104, Bibcode:2007A&A...474...77K, arXiv:0707.2746 Freely accessible, doi:10.1051/0004-6361:20077719.
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