KT Lupi

A light curve for KT Lupi, plotted from Hipparcos data [1]
Observation data
Epoch J2000      Equinox J2000
Constellation Lupus
Right ascension 15h 35m 53.24806s[2]
Declination −44° 57′ 30.1982″[2]
Apparent magnitude (V) 4.55[3] (4.66 + 6.62)[4]
Characteristics
Spectral type B3 V + B6 V[5]
B−V color index −0.175±0.003[3]
Variable type Be[6]
Astrometry
Radial velocity (Rv)+6.5±2.8[7] km/s
Proper motion (μ) RA: −20.53[2] mas/yr
Dec.: −21.23[2] mas/yr
Parallax (π)7.62 ± 0.43 mas[2]
Distance430 ± 20 ly
(131 ± 7 pc)
Absolute magnitude (MV)−1.03[3]
Details
KT Lup A
Mass5.9±0.1[8] M☉
Radius3.00±0.06[9] R☉
Luminosity794+791
−396[10] L☉
Surface gravity (log g)3.50±0.04[9] cgs
Temperature18,400±184[9] K
Rotational velocity (v sin i)30±0.6[9] km/s
Age21.0±10.6[8] Myr
KT Lup B
Mass2.79[11] M☉
Other designations
d Lup, KT Lup, CD−44°10239, HD 138769, HIP 76371, HR 5781, SAO 225950, WDS J15359-4457AB[12]
Database references
SIMBADdata

KT Lupi is a visual binary star[5] system in the constellation Lupus. It is visible to the naked eye with a combined apparent visual magnitude of 4.55.[3] As of 1983, the pair had an angular separation of 2.19″±0.03″.[10] Based upon an annual parallax shift of 7.6 mas[2] as seen from Earth's orbit, it is located 430 light-years from the Sun. The system is moving further from the Earth with a heliocentric radial velocity of +6.5 km/s.[7] It is a member of the Lower Centaurus–Crux sub-group of the Scorpius–Centaurus association.[5]

The primary, component A, is a variable Be star,[6] with the variation being modulated by rotation.[13] It is visual magnitude 4.66[4] with a stellar classification of B3 V,[5] matching a B-type main-sequence star. Hiltner et al. (1969) gave a class of B3 IVp,[14] which is still used in some studies.[8][9][10] It is a helium-weak chemically peculiar star showing an enhanced silicon patch near the equator and a silicon-weak region close to the pole.[10] The star is about 21 million years old with nearly six[8] times the mass of the Sun and three times the Sun's radius.[9] It is radiating roughly 794[10] times the Sun's luminosity from its photosphere at an effective temperature of 18,400 K.[9]

The secondary companion, component B, is of magnitude 6.62[4] with a class of B6 V.[5] It has 2.79 times the Sun's mass.[11]

References

  1. ↑ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
  2. 1 2 3 4 5 6 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.
  3. 1 2 3 4 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  4. 1 2 3 Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  5. 1 2 3 4 5 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.
  6. 1 2 Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  7. 1 2 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.
  8. 1 2 3 4 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, S2CID 118629873.
  9. 1 2 3 4 5 6 7 Arcos, C.; et al. (March 2018), "Stellar parameters and H α line profile variability of Be stars in the BeSOS survey", Monthly Notices of the Royal Astronomical Society, 474 (4): 5287–5299, arXiv:1711.08675, Bibcode:2018MNRAS.474.5287A, doi:10.1093/mnras/stx3075, S2CID 74872624.
  10. 1 2 3 4 5 Briquet, M.; et al. (January 2007), "Discovery of magnetic fields in three He variable Bp stars with He and Si spots", Astronomische Nachrichten, 328 (1): 41–45, arXiv:astro-ph/0610537, Bibcode:2007AN....328...41B, doi:10.1002/asna.200610702, S2CID 18724568.
  11. 1 2 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, arXiv:0707.2746, Bibcode:2007A&A...474...77K, doi:10.1051/0004-6361:20077719, S2CID 15750945.
  12. ↑ "KT Lup". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 3 September 2018.
  13. ↑ Briquet, M.; et al. (January 2004), "He and Si surface inhomogeneities of four Bp variable stars", Astronomy and Astrophysics, 413: 273–283, Bibcode:2004A&A...413..273B, doi:10.1051/0004-6361:20031450
  14. ↑ Hiltner, W. A.; et al. (July 1969), "MK Spectral Types for Bright Southern OB Stars", Astrophysical Journal, 157: 313, Bibcode:1969ApJ...157..313H, doi:10.1086/150069
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