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 | B9Ve [3] or B7 IV [4] |
U−B color index | −0.44 [2] |
B−V color index | −0.125 [2] |
R−I color index | −0.09 [5] |
Astrometry | |
Radial velocity (Rv) | +35.0 [6] km/s |
Proper motion (μ) |
RA: −1.58
[1]
mas/
yr Dec.: −24.82 [1] mas/ yr |
Parallax (π) | 12.48 ± 0.36 mas [1] |
Distance | 261 ± 8
ly (80 ± 2 pc) |
Absolute magnitude (MV) | −1.87 [7] |
Details | |
Mass | 4.5 [8] M☉ |
Radius | 5.8 [9] R☉ |
Luminosity (bolometric) | 1,000 [8] L☉ |
Surface gravity (log g) | 3.73 [9] cgs |
Temperature | 12,963 [9] K |
Rotational velocity (v sin i) | 176 [10] km/s |
Age | 93 [3] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Alpha Columbae or α Columbae, officially named Phact ( /ˈfækt/), [12] [13] is a third magnitude star in the southern constellation of Columba. 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]
α Columbae, Latinized to Alpha Columbae, is the star's Bayer designation.
The traditional name of Phact (also rendered Phad, Phaet, Phakt) [14] derives from the Arabic فاختة fākhitah ' ring dove'. It was originally applied to the constellation Cygnus and later transferred to this star. [15] [16] [17] [18] The etymology of its name hadāri (unknown meaning) [19] has also been suggested. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) [20] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 [21] included a table of the first two batches of names approved by the WGSN; which included Phact for this star.
In Chinese, 丈人 (Zhàng Rén), meaning Grandfather, refers to an asterism consisting of α Columbae and ε Columbae. [22] Consequently, α Columbae itself is known as 丈人一 (Zhàng Rén yī, English: the First Star of Grandfather.). [23] From this Chinese name, the name Chang Jin has appeared [24]
This is believed to be a solitary star, [10] [25] although it has a faint optical companion at an angular separation of 13.5 arcseconds, making it a double star. [26] The stellar classification of Alpha Columbae is B9Ve, [3] matching a B-type main-sequence 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. [14] 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. [10] It is a suspected Gamma Cassiopeiae type (GCAS) variable star, with its apparent magnitude varying from 2.62m to 2.66m.
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 | B9Ve [3] or B7 IV [4] |
U−B color index | −0.44 [2] |
B−V color index | −0.125 [2] |
R−I color index | −0.09 [5] |
Astrometry | |
Radial velocity (Rv) | +35.0 [6] km/s |
Proper motion (μ) |
RA: −1.58
[1]
mas/
yr Dec.: −24.82 [1] mas/ yr |
Parallax (π) | 12.48 ± 0.36 mas [1] |
Distance | 261 ± 8
ly (80 ± 2 pc) |
Absolute magnitude (MV) | −1.87 [7] |
Details | |
Mass | 4.5 [8] M☉ |
Radius | 5.8 [9] R☉ |
Luminosity (bolometric) | 1,000 [8] L☉ |
Surface gravity (log g) | 3.73 [9] cgs |
Temperature | 12,963 [9] K |
Rotational velocity (v sin i) | 176 [10] km/s |
Age | 93 [3] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Alpha Columbae or α Columbae, officially named Phact ( /ˈfækt/), [12] [13] is a third magnitude star in the southern constellation of Columba. 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]
α Columbae, Latinized to Alpha Columbae, is the star's Bayer designation.
The traditional name of Phact (also rendered Phad, Phaet, Phakt) [14] derives from the Arabic فاختة fākhitah ' ring dove'. It was originally applied to the constellation Cygnus and later transferred to this star. [15] [16] [17] [18] The etymology of its name hadāri (unknown meaning) [19] has also been suggested. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) [20] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 [21] included a table of the first two batches of names approved by the WGSN; which included Phact for this star.
In Chinese, 丈人 (Zhàng Rén), meaning Grandfather, refers to an asterism consisting of α Columbae and ε Columbae. [22] Consequently, α Columbae itself is known as 丈人一 (Zhàng Rén yī, English: the First Star of Grandfather.). [23] From this Chinese name, the name Chang Jin has appeared [24]
This is believed to be a solitary star, [10] [25] although it has a faint optical companion at an angular separation of 13.5 arcseconds, making it a double star. [26] The stellar classification of Alpha Columbae is B9Ve, [3] matching a B-type main-sequence 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. [14] 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. [10] It is a suspected Gamma Cassiopeiae type (GCAS) variable star, with its apparent magnitude varying from 2.62m to 2.66m.