Eta Leonis
Binary star system in the constellation Leo
From Wikipedia, the free encyclopedia
Eta Leonis (η Leo, η Leonis) is a third-magnitude blue supergiant star in the constellation Leo, about 1,270 light years away.
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Leo |
| Right ascension | 10h 07m 19.9519s[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 |
Nomenclature
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.[9] 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.[10]