Lambda Mensae

Lambda Mensae, Latinized from λ Mensae, is an orange-hued star in the southern constellation of Mensa. It has an apparent visual magnitude of 6.53,[2] which places it at or near the limit on stars visible to the naked eye. According to the Bortle scale, it requires a dark night from rural skies for this star to be viewed. Though it has the designation Lambda, it is actually the twenty-fourth-brightest star in the constellation and not the eleventh-brightest. Based upon an annual parallax shift of 6.9873 mas as seen from GAIA,[7] this star is located roughly 467 light years from the Sun.

Lambda Mensae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Mensa
Right ascension 05h 47m 48.13340s[1]
Declination −72° 42′ 08.0993″[1]
Apparent magnitude (V) 6.53[2]
Characteristics
Spectral type K0 III[3]
Apparent magnitude (B) 7.614[4]
Apparent magnitude (J) 4.820[5]
Apparent magnitude (H) 4.163[5]
Apparent magnitude (K) 4.119[5]
U−B color index +0.97[2]
B−V color index +1.08[2]
Astrometry
Radial velocity (Rv)13.67±0.59[6] km/s
Proper motion (μ) RA: −7.181[7] mas/yr
Dec.: +24.522[7] mas/yr
Parallax (π)6.9873 ± 0.0220[7] mas
Distance467 ± 1 ly
(143.1 ± 0.5 pc)
Absolute magnitude (MV)+0.84[8]
Details
Radius10[9] R☉
Luminosity54[10] L☉
Surface gravity (log g)2.43[6] cgs
Temperature4,713[6] K
Other designations
λ Men, CPD−72° 289, HD 39810, HIP 27369, HR 2062, SAO 256239[11]
Database references
SIMBADdata

This is an evolved K-type giant star with a stellar classification of K0 III.[3] It is a red clump star, which means it is generating energy through helium fusion at its core.[5] The measured angular diameter is 0.68±0.01 mas.[12] At an estimated distance of the star, this yields a physical size of about 10 times the radius of the Sun.[9] It is radiating 54[10] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,713 K.[6]

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, S2CID 18759600.
  2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  3. Houk, Nancy; Cowley, A. P. (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. Høg, E.; et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics, 355: L27, Bibcode:2000A&A...355L..27H, doi:10.1888/0333750888/2862.
  5. Laney, C. D.; et al. (January 2012), "A new Large Magellanic Cloud K-band distance from precision measurements of nearby red clump stars", Monthly Notices of the Royal Astronomical Society, 419 (2): 1637–1641, arXiv:1109.4800, Bibcode:2012MNRAS.419.1637L, doi:10.1111/j.1365-2966.2011.19826.x, S2CID 117788450.
  6. Kordopatis, G.; Gilmore, G.; Steinmetz, M.; Boeche, C.; Seabroke, G. M.; Siebert, A.; Zwitter, T.; Binney, J.; et al. (November 2013), "The Radial Velocity Experiment (RAVE): Fourth Data Release", The Astronomical Journal, 146 (5): 36, arXiv:1309.4284, Bibcode:2013AJ....146..134K, doi:10.1088/0004-6256/146/5/134, S2CID 119221010, 134.
  7. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
  8. 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.
  9. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
  10. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
  11. "lam Men". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-15.
  12. Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
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