Lambda Pavonis

λ Pavonis, Latinized as Lambda Pavonis, is a single,[13] variable star in the southern constellation of Pavo. It is a blue-white hued star that is faintly visible to the naked eye with an apparent visual magnitude that fluctuates around 4.22.[2] This object is located approximately 1,400 light years from the Sun, based upon parallax. It is a member of the Scorpius-Centaurus Association.[14]

Lambda Pavonis
Location of λ Pavonis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pavo
Right ascension  18h 52m 13.03427s[1]
Declination −62° 11′ 15.3324″[1]
Apparent magnitude (V) 4.22[2] (4.00 - 4.26)[3]
Characteristics
Spectral type B2Ve[4] or B2II–IIIe[5]
U−B color index −0.88[6]
B−V color index −0.15[2]
Variable type γ Cas[3]
Astrometry
Radial velocity (Rv)+9.0±4.1[7] km/s
Proper motion (μ) RA: −1.86[1] mas/yr
Dec.: −13.02[1] mas/yr
Parallax (π)2.28 ± 0.18[1] mas
Distance1,400 ± 100 ly
(440 ± 30 pc)
Absolute magnitude (MV)−3.97[2]
Details
Mass12.5[8] M☉
Radius9±1[9] (polar) R☉
Luminosity8,450[2] L☉
Temperature20,300[10] K
Rotational velocity (v sin i)190[11] km/s
Other designations
λ Pav, CD−62°1254, FK5 704, GC 25823, HD 173948, HIP 92609, HR 7074, SAO 254393, CCDM J18522-6212A, WDS J18522-6211[12]
Database references
SIMBADdata

This is a massive Be star, a rapidly rotating hot blue star which has developed a gas disk around it. It is a γ Cassiopeiae variable or shell star which has occasionally brightened to magnitude 4.0.[3] The stellar classification of B2Ve[4] suggests it is a B-type main-sequence star that is generating energy through core hydrogen fusion. This star is spinning rapidly with a projected rotational velocity of 190 km/s.[11] This is giving the star an oblate shape with an equatorial bulge that is an estimated 10% larger than the polar radius.[15] Lambda Pavonis has 12.5[8] times the mass of the Sun and nine times the Sun's polar radius.[9] It is radiating 8,450[2] times the luminosity of the Sun from its photosphere at an effective temperature of 20,300 K.[10]

Variations in signals coming from Lambda Pavonis have led to a debate on whether it is a binary, single or pulsating variable star.[14]

References
  1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
  2. 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. Vizier catalog entry
  3. Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085.
  4. Levenhagen, R. S.; Leister, N. V. (2006). "Spectroscopic analysis of southern B and Be stars". Monthly Notices of the Royal Astronomical Society. 371: 252. arXiv:astro-ph/0606149. Bibcode:2006MNRAS.371..252L. doi:10.1111/j.1365-2966.2006.10655.x.
  5. Samus, N. N.; Durlevich, O. V.; et al. (2009). "General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  6. Mermilliod, J. C. (2006). "Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
  7. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  8. Tetzlaff, N.; et al. (2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410: 190. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. Vizier catalog entry
  9. Vieira, R. G.; et al. (January 2017). "The life cycles of Be viscous decretion discs: time-dependent modelling of infrared continuum observations". Monthly Notices of the Royal Astronomical Society. 464 (3): 3071–3089. arXiv:1707.02861. Bibcode:2017MNRAS.464.3071V. doi:10.1093/mnras/stw2542.
  10. Hohle, M. M.; et al. (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.
  11. Glebocki, R.; Gnacinski, P. (2005). "VizieR Online Data Catalog: Catalog of Stellar Rotational Velocities (Glebocki+ 2005)". VizieR On-line Data Catalog: III/244. Originally Published in: 2005csss...13..571G. 3244. Bibcode:2005yCat.3244....0G. Vizier catalog entry
  12. "lam Pav". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-20.
  13. 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.
  14. Levenhagen, R. S.; et al. (2011). "Spectroscopic variabilities in λ Pavonis". Astronomy & Astrophysics. 533: 75–75. Bibcode:2011A&A...533A..75L. doi:10.1051/0004-6361/201116590.
  15. 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.
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