Rigel
 Rigel in the constellation Orion |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Orion |
| A | |
| Right ascension | 05h 14m 32.27210s |
| Declination | −08° 12′ 05.8981″ |
| Apparent magnitude (V) | 0.13(0.05 - 0.18) |
| B | |
| Right ascension | 05h 14m 32.049s |
| Declination | −08° 12′ 14.78″ |
| Apparent magnitude (V) | 6.67 |
| Characteristics | |
| A | |
| Evolutionary stage | Blue supergiant |
| Spectral type | B8 Ia |
| U−B color index | −0.66 |
| B−V color index | −0.03 |
| Variable type | Alpha Cygni |
| B | |
| Evolutionary stage | Spectroscopic binary |
| Spectral type | B9V + B9V |
| U−B color index | −0.66 |
| B−V color index | −0.03 |
| Variable type | Alpha Cygni |
| Astrometry | |
| Radial velocity (Rv) | 17.8±0.4 km/s |
| Proper motion (μ) |
RA: +1.31 mas/yr Dec.: +0.50 mas/yr |
| Parallax (π) | 3.78 ± 0.34mas |
| Distance | 860 ± 80 ly (260 ± 20 pc) |
| Absolute magnitude (MV) | -7.84 |
| Orbit | |
| Primary | Ba |
| Companion | Bb |
| Period (P) | 9.860 days |
| Eccentricity (e) | 0.1 |
|
Semi-amplitude (K1) (primary) |
25.0 km/s |
|
Semi-amplitude (K2) (secondary) |
32.6 km/s |
| Details | |
| A | |
| Mass | 23 M☉ |
| Radius | 78.9±7.4 R☉ |
| Luminosity (bolometric) |
1.20+0.25 −0.21×105 L☉ |
| Surface gravity (log g) | 1.75±0.10 cgs |
| Temperature | 12100±150 K |
| Metallicity [Fe/H] | −0.06±0.10 dex |
| Rotational velocity (v sin i) | 25±3 km/s |
| Age | 8±1 Myr |
| Ba | |
| Mass | 3.84 M☉ |
| Bb | |
| Mass | 2.94 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
Rigel, also designated Beta Orionis (β Orionis, abbreviated Beta Ori, β Ori), is generally the seventh-brightest star in the night sky and the brightest star in the constellation of Orion—though there are times where it is outshone in the constellation by the variable Betelgeuse. With a visual magnitude of 0.13, it is a remote and luminous star some 863 light-years distant from Earth.
The star as seen from Earth is actually a triple, quadruple or quintuple star system, with the primary star (Rigel A) a blue-white supergiant that is estimated to be anywhere from 120,000 to 279,000 times as luminous as the Sun, depending on method used to calculate its properties. It has exhausted its core hydrogen and swollen out to between 79 and 115 times the Sun's radius. It pulsates quasi-periodically and is classified as an Alpha Cygni variable. A companion, Rigel B, is 500 times fainter than the supergiant Rigel A and visible only with a telescope. Rigel B is itself a spectroscopic binary system, consisting of two main sequence blue-white stars of spectral type B9V that are estimated to be respectively 3.9 and 2.9 times as massive as the Sun, Rigel Bb may itself be a binary. Rigel B also appears to have a very close visual companion Rigel C of almost identical appearance.
Beta Orionis is the star's Bayer designation. The traditional name Rigel is first recorded in the Alfonsine Tables of 1252. It is derived from the Arabic name Rijl Jauzah al Yusrā, "the left leg (foot) of Jauzah" (i.e. rijl meaning "leg, foot"), which can be traced to the 10th century. "Jauzah" was a proper name of the Orion figure, an alternative Arabic name was رجل الجبار riǧl al-ǧabbār, "the foot of the great one", which is the source of the rarely used variant names Algebar or Elgebar. The Alphonsine Tables saw its name split into "Rigel" and "Algebar", with the note, "et dicitur Algebar. Nominatur etiam Rigel." Alternate spellings from the 17th century include Regel by Giovanni Battista Riccioli, Riglon by Wilhelm Schickard, and Rigel Algeuze or Algibbar by Edmund Chilmead.
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