Beta Leporis (β Leporis, abbreviated Beta Lep, β Lep), formally named Nihal /ˈnaɪ.æl/,[10][11] is the second brightest star in the constellation of Lepus.[12]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lepus |
| Right ascension | 05h 28m 14.72316s[1] |
| Declination | −20° 45′ 33.9878″[1] |
| Apparent magnitude (V) | 2.813[2] |
| Characteristics | |
| Spectral type | G5 II[3] |
| U−B color index | +0.47[4] |
| B−V color index | +0.808[2] |
| R−I color index | +0.44[5] |
| Astrometry | |
| Radial velocity (Rv) | −13.6 ± 0.9[6] km/s |
| Proper motion (μ) | RA: −5.02[1] mas/yr Dec.: −85.92[1] mas/yr |
| Parallax (π) | 20.34 ± 0.18 mas[1] |
| Distance | 160 ± 1 ly (49.2 ± 0.4 pc)[1] |
| Absolute magnitude (MV) | −0.65[7] |
| Details | |
| Mass | 2.948±0.031[2] M☉ |
| Radius | 12.573±0.153[2] R☉ |
| Luminosity | 171[8] L☉ |
| Surface gravity (log g) | 2.88[2] cgs |
| Temperature | 5,398[2] K |
| Metallicity [Fe/H] | −0.08±0.02[2] dex |
| Rotational velocity (v sin i) | 11[9] km/s |
| Age | 391±11[2] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Nomenclature
Beta Leporis is the star's Bayer designation. It is also known by the traditional named Nihal, Arabic for "quenching their thirst". The occasional spelling Nibal appears to be due to a misreading.[13] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[14] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[15] included a table of the first two batches of names approved by the WGSN; which included Nihal for this star.
In Chinese, 廁 (Cè), meaning Toilet, refers to an asterism consisting of β Leporis, α Leporis, γ Leporis and δ Leporis.[16] Consequently, the Chinese name for β Leporis itself is 廁二 (Cè èr), "the Second Star of Toilet".[17]
Properties
Based on parallax measurements from the Hipparcos astrometry satellite,[18] this star is located about 160 light-years (49 parsecs) from the Earth. It has an apparent visual magnitude of 2.81[2] and a stellar classification of G5 II.[3] The mass of this star is 3 times the mass of the Sun and it is about 390 million years old,[2] which is the sufficient time for a star this massive to consume the hydrogen at its core and evolve away from the main sequence, becoming a G-type bright giant.[3] Currently, it has expanded to 12.6 times the Sun's size[2] and is emitting 171 times its luminosity.[8]
This is a double star system and may be a binary, whereby the second star has a brightness of 7.34 mag.[19] Using adaptive optics on the AEOS telescope at Haleakala Observatory, the pair was found to be separated by an angle of 2.58 arcseconds at a position angle of 1.4°.[20] Component B has been observed to fluctuate in brightness and is catalogued as suspected variable star NSV 2008.[21]