KT Lupi

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

KT Lupi is a visual binary star system in the constellation Lupus. It is visible to the naked eye with a combined apparent visual magnitude of 4.55. As of 1983, the pair had an angular separation of 2.19″±0.03″. Based upon an annual parallax shift of 7.6 mas 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. It is a member of the Upper Centaurus-Lupus sub-group of the Scorpius–Centaurus association.

A light curve for KT Lupi, plotted from Hipparcos data

The primary, component A, is a variable Be star, with the variation being modulated by rotation. It is visual magnitude 4.66 with a stellar classification of B3 V, matching a B-type main-sequence star. Hiltner et al. (1969) gave a class of B3 IVp, which is still used in some studies. 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. The star is about 21 million years old with nearly six times the mass of the Sun and three times the Sun's radius. It is radiating roughly 794 times the Sun's luminosity from its photosphere at an effective temperature of 18,400 K.

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

References

  1. 1 2 3 4 5 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. XHIP record for this object at VizieR.
  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 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. ↑ "KT Lup". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 3 September 2018.
  12. ↑ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
  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