Iota Lupi

ι Lupi, Latinised as Iota Lupi, is a solitary[11] star in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 3.54.[2] Based upon an annual parallax shift of 9.65 mas as seen from Earth, it is located around 338 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.23 due to interstellar dust.[5] Relative to its neighbors, this star has a peculiar velocity of 27.4±4.9 km/s.[6] It appears to be a member of the Scorpio-Centaurus OB association.[12]

ι Lupi
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Lupus
Right ascension 14h 19m 24.22219s[1]
Declination −46° 03′ 29.1437″[1]
Apparent magnitude (V) 3.54[2]
Characteristics
Spectral type B2.5 IV[3]
U−B color index −0.742[2]
B−V color index −0.180[2]
Astrometry
Radial velocity (Rv)21.6±4.1[4] km/s
Proper motion (μ) RA: −12.56[1] mas/yr
Dec.: −4.76[1] mas/yr
Parallax (π)9.65 ± 0.20[1] mas
Distance338 ± 7 ly
(104 ± 2 pc)
Absolute magnitude (MV)−1.48[5]
Details
Mass6.9±0.1[6] M☉
Radius4.05±0.33[7] R☉
Luminosity (bolometric)2,082[8] L☉
Surface gravity (log g)3.94±0.07[7] cgs
Temperature18,605±221[7] K
Metallicity [Fe/H]+0.19±0.15[7] dex
Rotational velocity (v sin i)370[9] km/s
Age20.3±4.8[6] Myr
Other designations
ι Lup, CD−45° 9084, HD 125238, HIP 69996, HR 5354, SAO 224833.[10]
Database references
SIMBADdata

This star has the spectrum of a B-type subgiant star with a stellar classification of B2.5 IV,[3] which may indicate that it has used up its core supply of hydrogen and has begun to expand off the main-sequence. It is rotating rapidly with a projected rotational velocity of 370 km/s.[9] This is giving the star an oblate shape with an equatorial bulge that is an estimated 12% larger than the polar radius.[13] It is about 20[6] million years old with 6.9[6] times the mass of the Sun and 4[7] times the Sun's radius. The star radiates 2,082[8] times the solar luminosity from its outer atmosphere at an effective temperature of 18,605[7] K.

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.
  2. Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement, 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168.
  3. Hiltner, W. A.; et al. (July 1969), "MK Spectral Types for Bright Southern OB Stars", Astrophysical Journal, 157: 313–326, Bibcode:1969ApJ...157..313H, doi:10.1086/150069.
  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, A61.
  5. Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.
  6. 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, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.
  7. Fitzpatrick, E. L.; Massa, D. (March 2005), "Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry", The Astronomical Journal, 129 (3): 1642–1662, arXiv:astro-ph/0412542, Bibcode:2005AJ....129.1642F, doi:10.1086/427855.
  8. 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:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355.
  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. "iot Lup -- Variable Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-03-05.
  11. 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.
  12. de Geus, E. J.; et al. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics, 216 (1–2): 44–61, Bibcode:1989A&A...216...44D.
  13. Belle, G. T. (2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20: 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2.
  • Kaler, James B. (August 9, 2013), "Iota Lupi", Stars, University of Illinois, retrieved 2017-03-06.
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