Kept on Wikipedia:Alnilam
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 36m 12.8s[1] |
| Declination | −01° 12′ 06.9″[1] |
| Apparent magnitude (V) | 1.69[2] |
| Characteristics | |
| Spectral type | B0 Ia[3] |
| Variable type | α Cygni[4] |
| Astrometry | |
| Radial velocity (Rv) | 25.9[5] km/s |
| Parallax (π) | 1.65 ± 0.45[1] mas |
| Distance | approx. 2,000 ly (approx. 600 pc) |
| Absolute magnitude (MV) | −6.89[6] |
| Details | |
| Mass | 40[6] M☉ |
| Radius | 32.4[6] R☉ |
| Luminosity | 537,000[6] L☉ |
| Temperature | 27,500±100[6] K |
| Age | 5.7[7] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Alnilam, also designated ε Orionis (Latinized to Epsilon Orionis), is a large blue supergiant star about 2,000 light-years distant in the constellation of Orion. It is estimated to be up to 832,000 times as luminous as the Sun and 30–64.5 times as massive.
Observation
Alnilam is the 29th-brightest star in the sky and the 4th-brightest in Orion. It is a blue-white supergiant and forms Orion's Belt with Mintaka and Alnitak. Alnilam is the middle star and slightly variable, from magnitude 1.64 to 1.74. Since 1943, the spectrum of this star has served as a standard for classification. It is also one of the 58 stars used in celestial navigation.
Physical characteristics
Alnilam's properties vary by analysis. Estimates include a luminosity up to 832,000 times that of the Sun, an effective temperature of 27,500 K, and a radius up to 32.4 times that of the Sun. It is estimated to be 34.6 times as massive as the Sun and about 5.7 million years old. Alnilam's stellar winds may reach up to 2,000 km/s, causing significant mass loss.
Nomenclature and history
The traditional name Alnilam derives from the Arabic Al-nilam, related to the word for sapphire. The star's Bayer designation is ε Orionis and its Flamsteed designation is 46 Orionis. In 2016, the International Astronomical Union approved the name Alnilam for this star.
Orion's Belt
The three belt stars were known by many names in various cultures. In Arabic, they were known as Al Nijād (the Belt) and in Chinese as Shēn Sù (Three Stars).
References
- ↑ 1.0 1.1 1.2 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- ↑ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedmkk - ↑ Ruban, E. V.; Alekseeva, G. A.; Arkharov, A. A.; Hagen-Thorn, E. I.; Galkin, V. D.; Nikanorova, I. N.; Novikov, V. V.; Pakhomov, V. P.; Puzakova, T. Yu. (September 2006). "Spectrophotometric observations of variable stars". Astronomy Letters. 32 (9): 604–607. Bibcode:2006AstL...32..604R. doi:10.1134/S1063773706090052.
- ↑ Gontcharov, G. A. (November 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.
- ↑ 6.0 6.1 6.2 6.3 6.4 Cite error: Invalid
<ref>tag; no text was provided for refs namedSearle 2008 - ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedVoss 2010
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