Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Boötes |
Right ascension | 14h 25m 11.79703s [1] |
Declination | +51° 51′ 02.6769″ [1] |
Apparent magnitude (V) | 4.05 [2] + 13.23 [3] |
Characteristics | |
Spectral type | F7 V [2] + M2.5V [3] |
U−B color index | −0.02 [4] |
B−V color index | +0.50 [2] |
Astrometry | |
Radial velocity (Rv) | −10.627±0.0065 [5] km/s |
Proper motion (μ) |
RA: −235.40
[1]
mas/
yr Dec.: −399.07 [1] mas/ yr |
Parallax (π) | 68.82 ± 0.14 mas [1] |
Distance | 47.39 ± 0.10
ly (14.53 ± 0.03 pc) |
Absolute magnitude (MV) | 3.25 [6] |
Details | |
A | |
Mass | 1.41 M☉
[7] 1.24 [8] M☉ |
Radius | 1.733±0.011 [9] R☉ |
Luminosity | 4.131±0.096 [9] L☉ |
Surface gravity (log g) | 4.07 [8] cgs |
Temperature | 6,294±40 [8] K |
Metallicity [Fe/H] | 0.03 [8] dex |
Rotational velocity (v sin i) | 29.2 [10] km/s |
Age | 3.1 Gyr
[11] 3.83 [8] Gyr |
B | |
Mass | 0.21 [7] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
ARICNS | data |
Theta Boötis, Latinized from θ Boötis, is a star in the northern constellation of Boötes the herdsman, forming a corner of the upraised left hand of this asterism. [13] It has the traditional name Asellus Primus ( /əˈsɛləs ˈpraɪməs/; Latin for "first donkey colt") [13] and the Flamsteed designation 23 Boötis. Faintly visible to the naked eye, this star has a yellow-white hue with an apparent visual magnitude of 4.05. [2] It is located at a distance of 47 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −10.6 km/s. [5]
The stellar classification of Theta Boötis is F7 V, [2] matching an F-type main-sequence star. It is a solar-type star that may be near the end of its main sequence lifetime based on a high luminosity for a star of its type. [11] Theta Boötis is a suspected variable star [14] and a source of X-ray emission. [15] There is evidence for low amplitude radial velocity variation of about 5 km/s. [11] The star has a greater mass and a larger radius than the Sun. It is about 3–4 billion years old and is spinning with a projected rotational velocity of 29 km/s. [10] The star is radiating 4.1 [9] times the luminosity of the Sun from its photosphere at an effective temperature of 6,294 K. [8]
There is a nearby 11th magnitude optical companion star about 70 arcseconds away. This is a class M2.5 red dwarf that is separated by a minimum of 1,000 AUs. It is uncertain whether they are gravitationally bound, but they do have a common motion through space and so the two stars probably share a common origin. [16] [3]
θ Boötis, along with the other Aselli ( ι Boo and κ Boo) and λ Boo, were Aulād al Dhiʼbah (أولاد الضّباع - awlād al-ḍibā‘), "the Whelps of the Hyenas". [13]
In Chinese, 天枪 (Tiān Qiāng), meaning Celestial Spear, refers to an asterism consisting of θ Boötis, κ2 Boötis and ι Boötis. [17] Consequently, the Chinese name for θ Boötis itself is 天枪三 (Tiān Qiāng sān, English: the Third Star of Celestial Spear.) [18]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Boötes |
Right ascension | 14h 25m 11.79703s [1] |
Declination | +51° 51′ 02.6769″ [1] |
Apparent magnitude (V) | 4.05 [2] + 13.23 [3] |
Characteristics | |
Spectral type | F7 V [2] + M2.5V [3] |
U−B color index | −0.02 [4] |
B−V color index | +0.50 [2] |
Astrometry | |
Radial velocity (Rv) | −10.627±0.0065 [5] km/s |
Proper motion (μ) |
RA: −235.40
[1]
mas/
yr Dec.: −399.07 [1] mas/ yr |
Parallax (π) | 68.82 ± 0.14 mas [1] |
Distance | 47.39 ± 0.10
ly (14.53 ± 0.03 pc) |
Absolute magnitude (MV) | 3.25 [6] |
Details | |
A | |
Mass | 1.41 M☉
[7] 1.24 [8] M☉ |
Radius | 1.733±0.011 [9] R☉ |
Luminosity | 4.131±0.096 [9] L☉ |
Surface gravity (log g) | 4.07 [8] cgs |
Temperature | 6,294±40 [8] K |
Metallicity [Fe/H] | 0.03 [8] dex |
Rotational velocity (v sin i) | 29.2 [10] km/s |
Age | 3.1 Gyr
[11] 3.83 [8] Gyr |
B | |
Mass | 0.21 [7] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
ARICNS | data |
Theta Boötis, Latinized from θ Boötis, is a star in the northern constellation of Boötes the herdsman, forming a corner of the upraised left hand of this asterism. [13] It has the traditional name Asellus Primus ( /əˈsɛləs ˈpraɪməs/; Latin for "first donkey colt") [13] and the Flamsteed designation 23 Boötis. Faintly visible to the naked eye, this star has a yellow-white hue with an apparent visual magnitude of 4.05. [2] It is located at a distance of 47 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −10.6 km/s. [5]
The stellar classification of Theta Boötis is F7 V, [2] matching an F-type main-sequence star. It is a solar-type star that may be near the end of its main sequence lifetime based on a high luminosity for a star of its type. [11] Theta Boötis is a suspected variable star [14] and a source of X-ray emission. [15] There is evidence for low amplitude radial velocity variation of about 5 km/s. [11] The star has a greater mass and a larger radius than the Sun. It is about 3–4 billion years old and is spinning with a projected rotational velocity of 29 km/s. [10] The star is radiating 4.1 [9] times the luminosity of the Sun from its photosphere at an effective temperature of 6,294 K. [8]
There is a nearby 11th magnitude optical companion star about 70 arcseconds away. This is a class M2.5 red dwarf that is separated by a minimum of 1,000 AUs. It is uncertain whether they are gravitationally bound, but they do have a common motion through space and so the two stars probably share a common origin. [16] [3]
θ Boötis, along with the other Aselli ( ι Boo and κ Boo) and λ Boo, were Aulād al Dhiʼbah (أولاد الضّباع - awlād al-ḍibā‘), "the Whelps of the Hyenas". [13]
In Chinese, 天枪 (Tiān Qiāng), meaning Celestial Spear, refers to an asterism consisting of θ Boötis, κ2 Boötis and ι Boötis. [17] Consequently, the Chinese name for θ Boötis itself is 天枪三 (Tiān Qiāng sān, English: the Third Star of Celestial Spear.) [18]