Eta Leonis

Eta Leonis (η Leo, η Leonis) is a third-magnitude blue supergiant star in the constellation Leo, about 1,270 light years away.

Eta Leonis

Location of η Leo (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Leo
Right ascension	10h 07m 19.95186s[1]
Declination	16° 45′ 45.592″[1]
Apparent magnitude (V)	3.486[2]
Characteristics
Evolutionary stage	Blue supergiant (blue loop)[3]
Spectral type	A0 Ib[2]
U−B color index	−0.206[2]
B−V color index	−0.026[2]
Astrometry
Radial velocity (Rv)	1.40[4] km/s
Proper motion (μ)	RA: −2.80[1] mas/yr Dec.: −1.82[1] mas/yr
Parallax (π)	2.57 ± 0.16 mas[1]
Distance	1,270 ± 80 ly (390 ± 20 pc)
Absolute magnitude (MV)	−5.54[3]
Details
Mass	10[5] M☉
Radius	47[3] R☉
Luminosity	19,000[5] L☉
Surface gravity (log g)	2.00[5] cgs
Temperature	9,600[2] K
Metallicity	−0.04[3]
Rotational velocity (v sin i)	2[2] km/s
Age	25[5] Myr
Other designations
η Leo, 30 Leonis, HR 3975, BD+17°2171, HD 87737, FK5 379, HIP 49583, SAO 98955, GC 13899
Database references
SIMBAD	data

Properties

Eta Leonis is a blue supergiant with the stellar classification A0Ib. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.^[6] Though its apparent magnitude is 3.5, making it a relatively dim star to the naked eye, it is nearly 20,000 times more luminous than the Sun, with an absolute magnitude of -5.60. The Hipparcos astrometric data has estimated the distance of Eta Leonis to be roughly 390 parsecs from Earth, or 1,270 light years away. It is believed to be in a blue loop phase.^[3]

Eta Leonis is apparently a multiple star system, but the number of components and their separation is uncertain.^[7]

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. Firnstein, M.; Przybilla, N. (2012). "Quantitative spectroscopy of Galactic BA-type supergiants. I. Atmospheric parameters". Astronomy & Astrophysics. 543: A80. arXiv:1207.0308. Bibcode:2012A&A...543A..80F. doi:10.1051/0004-6361/201219034. S2CID 54725386.
3. Przybilla, N.; Butler, K.; Becker, S. R.; Kudritzki, R. P. (2006). "Quantitative spectroscopy of BA-type supergiants". Astronomy and Astrophysics. 445 (3): 1099. arXiv:astro-ph/0509669. Bibcode:2006A&A...445.1099P. doi:10.1051/0004-6361:20053832. S2CID 118953817.
4. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
5. Tanrıverdi, Taner (2013). "Elemental abundances of the supergiant stars σ Cygnus and η Leonis". New Astronomy. 25: 50. arXiv:1512.04557. Bibcode:2013NewA...25...50T. doi:10.1016/j.newast.2013.03.013. S2CID 118525375.
6. Garrison, R. F. (December 1993). "Anchor Points for the MK System of Spectral Classification". Bulletin of the American Astronomical Society. 25: 1319. Bibcode:1993AAS...183.1710G.
7. Mason, Brian D. (1996). "ICCD Speckle Observations of Binary Stars.XV.An Investigation of Lunar Occultation Systems". The Astronomical Journal. 112: 2260. Bibcode:1996AJ....112.2260M. doi:10.1086/118179.

External links

• Jim Kaler's Stars: Eta Leonis