Lambda Mensae

Lambda Mensae

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Mensa
Right ascension	05^h 47^m 48.13340^s[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)	15.35±0.13[6] km/s
Proper motion (μ)	RA: -7.013[6] mas/yr Dec.: +24.451[6] mas/yr
Parallax (π)	6.9890 ± 0.0139 mas[6]
Distance	466.7 ± 0.9 ly (143.1 ± 0.3 pc)
Absolute magnitude (MV)	+0.84[7]
Details
Radius	10[8] R☉
Luminosity	54[9] L☉
Surface gravity (log g)	2.43[10] cgs
Temperature	4,713[10] K
Other designations
λ Men, CPD−72° 289, HD 39810, HIP 27369, HR 2062, SAO 256239, 2MASS J05474813-7242080[11]
Database references
SIMBAD	data

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.

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.^[8] It is radiating 54^[9] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,713 K.^[10]

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, vol. 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. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
7. 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.
8. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R_*) is given by:

   ${\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(138.7\cdot 0.68\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 20\cdot R_{\bigodot }\end{aligned}}}$

9. 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.
10. 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.
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.