Eta Leonis

Eta Leonis
Location of η Leo (circled)
Observation data
Epoch J2000      Equinox ICRS
Constellation Leo
Right ascension 10h 07m 19.9519s
Declination +16° 45′ 45.592″
Apparent magnitude (V) 3.486
Characteristics
Evolutionary stage Blue supergiant (blue loop)
Spectral type A0 Ib
U−B color index −0.206
B−V color index −0.026
Astrometry
Radial velocity (Rv)1.40 km/s
Proper motion (μ) RA: −2.80 mas/yr
Dec.: −1.82 mas/yr
Parallax (π)2.57±0.16 mas
Distance1,270 ± 80 ly
(390 ± 20 pc)
Absolute magnitude (MV)−5.54
Details
Mass10 M☉
Radius47 R☉
Luminosity19,000 L☉
Surface gravity (log g)2.00 cgs
Temperature9,600 K
Metallicity−0.04
Rotational velocity (v sin i)2 km/s
Age25 Myr
Other designations
η Leo, 30 Leonis, HR 3975, BD+17°2171, HD 87737, FK5 379, HIP 49583, SAO 98955, GC 13899
Database references
SIMBADdata

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

Nomenclature

With Regulus, γ Leonis (Algieba), and ζ Leonis (Adhafera), it formed the Arabic lunar mansion Al Jabhah, the forehead (of the lion). Some sources apply the name Al Jabhah to this star specifically, though the name Algieba for γ Leonis has the same etymology.

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. 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.

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

References

  1. 1 2 3 4 5 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. 1 2 3 4 5 6 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. 1 2 3 4 5 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. 1 2 3 4 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. ↑ Allen, R. H. (1899), Star Names: Their Lore and Meaning, p. 257
  7. ↑ Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars (PDF), Jet Propulsion Laboratory, California Institute of Technology.
  8. ↑ Ridpath, Ian. "Star Tales - Leo". Retrieved 28 July 2025.
  9. ↑ 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.
  10. ↑ 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.