Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Draco |
Pronunciation | /ælˈruːbə/ |
Right ascension | 17h 43m 59.17049s [1] |
Declination | +54° 48′ 06.1637″ [1] |
Apparent magnitude (V) | 5.76 [2] |
Characteristics | |
Evolutionary stage | Main sequence [3] |
Spectral type | A0V [4] |
Astrometry | |
Radial velocity (Rv) | −2.0 [5] km/s |
Proper motion (μ) |
RA: 17.450
[1]
mas/
yr Dec.: −18.125 [1] mas/ yr |
Parallax (π) | 7.1436 ± 0.0605 mas [1] |
Distance | 457 ± 4
ly (140 ± 1 pc) |
Details | |
Mass | 2.97±0.07 [3] M☉ |
Luminosity | 146.7+29.6 −24.7 [3] L☉ |
Surface gravity (log g) | 3.80±0.10 [6] cgs |
Temperature | 9,226+107 −106 [3] K |
Metallicity [Fe/H] | −0.40±0.11 [6] dex |
Rotational velocity (v sin i) | 170 [3] km/s |
Age | 58 [7] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Alruba, [9] a name derived from Arabic for "the foal", is a suspected astrometric binary [10] star system in the northern circumpolar constellation of Draco. It is just barely visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.76. [2] Based on parallax measurements obtained during the Gaia mission, it is located at a distance of about 457 light-years (140 parsecs) from the Sun. The system is drifting closer with a radial velocity of −2 km/s. [5]
The visible component is an A-type main-sequence star with a stellar classification of A0 V. [4] It is about 58 [7] million years old with three [3] times the mass of the Sun and has a high rate of spin, showing a projected rotational velocity of 170 km/s. [3] The star is radiating 147 [3] times the luminosity of the Sun from its photosphere at an effective temperature of 9,226 K. [3] The system is a source for X-ray emission, which is most likely coming from the unseen companion. [11]
In the Henry Draper catalogue this system has the designation HD 161693, while it has the identifier HR 6618 in the Bright Star Catalogue. [8]
It bore the traditional Arabic name الربع Al Rubaʽ "the foal" (specifically a young camel born in the spring), a member of the Mother Camels asterism in early Arabic astronomy. [12] [13]
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) [14] to catalogue and standardize proper names for stars. The WGSN approved the name Alruba for this star on 1 June 2018 and it is now so entered on the List of IAU-approved Star Names. [9]
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Draco |
Pronunciation | /ælˈruːbə/ |
Right ascension | 17h 43m 59.17049s [1] |
Declination | +54° 48′ 06.1637″ [1] |
Apparent magnitude (V) | 5.76 [2] |
Characteristics | |
Evolutionary stage | Main sequence [3] |
Spectral type | A0V [4] |
Astrometry | |
Radial velocity (Rv) | −2.0 [5] km/s |
Proper motion (μ) |
RA: 17.450
[1]
mas/
yr Dec.: −18.125 [1] mas/ yr |
Parallax (π) | 7.1436 ± 0.0605 mas [1] |
Distance | 457 ± 4
ly (140 ± 1 pc) |
Details | |
Mass | 2.97±0.07 [3] M☉ |
Luminosity | 146.7+29.6 −24.7 [3] L☉ |
Surface gravity (log g) | 3.80±0.10 [6] cgs |
Temperature | 9,226+107 −106 [3] K |
Metallicity [Fe/H] | −0.40±0.11 [6] dex |
Rotational velocity (v sin i) | 170 [3] km/s |
Age | 58 [7] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Alruba, [9] a name derived from Arabic for "the foal", is a suspected astrometric binary [10] star system in the northern circumpolar constellation of Draco. It is just barely visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.76. [2] Based on parallax measurements obtained during the Gaia mission, it is located at a distance of about 457 light-years (140 parsecs) from the Sun. The system is drifting closer with a radial velocity of −2 km/s. [5]
The visible component is an A-type main-sequence star with a stellar classification of A0 V. [4] It is about 58 [7] million years old with three [3] times the mass of the Sun and has a high rate of spin, showing a projected rotational velocity of 170 km/s. [3] The star is radiating 147 [3] times the luminosity of the Sun from its photosphere at an effective temperature of 9,226 K. [3] The system is a source for X-ray emission, which is most likely coming from the unseen companion. [11]
In the Henry Draper catalogue this system has the designation HD 161693, while it has the identifier HR 6618 in the Bright Star Catalogue. [8]
It bore the traditional Arabic name الربع Al Rubaʽ "the foal" (specifically a young camel born in the spring), a member of the Mother Camels asterism in early Arabic astronomy. [12] [13]
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) [14] to catalogue and standardize proper names for stars. The WGSN approved the name Alruba for this star on 1 June 2018 and it is now so entered on the List of IAU-approved Star Names. [9]