Alpha Columbae
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
|
---|---|
Constellation | Columba |
Right ascension | 05h 39m 38.94103s[1] |
Declination | −34° 04′ 26.7950″[1] |
Apparent magnitude (V) | 2.645[2] |
Characteristics | |
Spectral type | B7 IV[3] |
U−B color index | −0.44[2] |
B−V color index | −0.125[2] |
R−I color index | −0.09[4] |
Astrometry | |
Radial velocity (Rv) | +35.0[5] km/s |
Proper motion (μ) | RA: −1.58[1] mas/yr Dec.: −24.82[1] mas/yr |
Parallax (π) | 12.48 ± 0.36[1] mas |
Distance | 261 ± 8 ly (80 ± 2 pc) |
Absolute magnitude (MV) | −1.9 |
Details | |
Mass | 4.5[6] M☉ |
Radius | 5.8[7] R☉ |
Luminosity (bolometric) | 1,000[6] L☉ |
Surface gravity (log g) | 3.73[7] cgs |
Temperature | 12,963[7] K |
Rotational velocity (v sin i) | 176[8] km/s |
Other designations | |
Database references | |
SIMBAD | data |
Alpha Columbae (α Columbae, α Col) is the Bayer designation for a third magnitude star in the southern constellation of Columba. It has the traditional name of Phact, which is derived from the Arabic term for "ring-necked dove". It has an apparent visual magnitude of 2.6,[2] making it the brightest member of Columba. Based upon parallax measurements made during the Hipparcos mission, Alpha Columbae is located at a distance of around 261 light-years (80 parsecs).[1]
Properties
This is believed to be a solitary star,[8][10] although it has a faint optical companion at an angular separation of 13.5 arcseconds, making it a double star.[11] The stellar classification of Alpha Columbae is B7 IV,[3] with the luminosity class of IV indicating it has evolved into a subgiant star. The spectrum shows it to be a Be star surrounded by a hot gaseous disk, which is generating emission lines because of hydrogen recombination.[12] Like most if not all such stars, it is rotating rapidly with a projected rotational velocity of 176 km s−1. The azimuthal equatorial velocity may be 457 km s−1.[8] It is a suspected Gamma Cassiopeiae type (GCAS) variable star, with its apparent magnitude varying from 2.62m to 2.66m.
Etymology
The proper name "Phact" (also Phad, Phaet, Phakt[12]) derived from the Arabic ألفاجتة - fākh(i)tah [fa:x(i)ta] which meaning "ring dove". It was originally applied to the constellation Cygnus as al-Fākhtah, but later transferred to this star.[13][14][15][16] The etymology of its name hadāri (unknown meaning)[17] has also been suggested.
In Chinese, 丈人 (Zhàng Rén), meaning Grandfather, refers to an asterism consisting of α Columbae and ε Columbae.[18] Consequently, α Columbae itself is known as 丈人一 (Zhàng Rén yī, English: the First Star of Grandfather.).[19] From this Chinese name, the name Chang Jin was appeared[20]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ HR 1956, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line April 21, 2009.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 6.0 6.1 Jim Kaler: Phact - STARS. Accessed on line April 21, 2009.
- ↑ 7.0 7.1 7.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 8.0 8.1 8.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ * alf Col -- Be Star, database entry, SIMBAD. Accessed on line April 21, 2009.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ CCDM J05396-3404, database entry, J. Dommanget and O. Nys (2002) Catalogue of the Components of Double and Multiple Stars, Accessed on line April 21, 2009.
- ↑ 12.0 12.1 Note of HR 1956, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line April 21, 2009.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ↑ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ↑ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Columbae