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]
Delta Aquarii, officially named Skat, is the third-brightest star in the constellation of Aquarius. The apparent visual magnitude is 3.3, which can be seen with the naked eye. The distance to this star is about 113 light-years based upon parallax measurements, and it has a close companion.
Theta Eridani, Latinized from θ Eridani, is a binary system in the constellation of Eridanus with a combined apparent magnitude of 2.88. Its two components are designated θ1 Eridani, formally named Acamar, and θ2 Eridani. The system's distance from the Sun based on parallax measurements is approximately 165 light-years.
21 Tauri, formally known as Asterope, is a component of the Asterope double star in the Pleiades open cluster. 21 Tauri is the stars' Flamsteed designation. This star is potentially faintly visible to the naked eye with an apparent visual magnitude of 5.76 in ideal conditions, although anybody viewing the object is likely to instead see the pair as a single elongated form of magnitude 5.6. The distance to 21 Tauri can be estimated from its annual parallax shift of 7.6 mas, yielding a range of around 431 light years. It is moving further from the Earth with a heliocentric radial velocity of +6 km/s.
Epsilon Aquarii, Latinized from ε Aquarii, is a single star in the equatorial zodiac constellation of Aquarius, located near the western constellation border with Capricornus. It has the proper name Albali, now formally recognized by the IAU. This is a white-hued star that is visible to the naked eye with an apparent visual magnitude of 3.77. Based upon parallax measurements taken during the Hipparcos mission, it is located at a distance of approximately 208 light-years (64 pc) from the Sun with an absolute magnitude of −0.46. The star is drifting closer with a radial velocity of −15 km/s.
Epsilon Cancri is a white-hued binary star system in the zodiac constellation of Cancer. It is the brightest member of the Beehive Cluster with an apparent visual magnitude of +6.29, which is near the lower limit of visibility with the naked eye. The annual parallax shift of 5.4 mas as seen from Earth yields a distance estimate of approximately 606 light-years from the Sun.
Beta1 Sagittarii, Latinized from β1 Sagittarii, is a binary star system in the zodiac constellation of Sagittarius, next to the southern constellation border with Telescopium. The brighter primary is named Arkab Prior, the traditional name of the system. It is visible to the naked eye with a combined apparent visual magnitude of +4.01. Based upon an annual parallax shift of 10.40 mas as seen from Earth, it is located roughly 310 light-years from the Sun. At Beta¹ Sagittarii's distance, the visual magnitude is diminished by an extinction factor of 0.17 due to interstellar dust.
Merope, designated 23 Tauri, is a star in the constellation of Taurus and a member of the Pleiades star cluster. It is approximately 440 light-years (135 pc) away.
Xi Andromedae, officially named Adhil, is a solitary star in the northern constellation of Andromeda. It has an apparent magnitude of +4.9. Based on parallax measurements obtained during the Gaia mission, it lies at a distance of roughly 223 light-years from the Sun.
Delta Antliae is the Bayer designation for a binary star system in the southern constellation of Antlia. The combined apparent visual magnitude of the system is +5.57, allowing it to be viewed from the suburbs with the naked eye. Judging by the parallax shift of this system, it is located at a distance of 450 ± 10 light-years from Earth. The system is reduced in magnitude by 0.03 due to extinction caused by intervening gas and dust.
41 Aurigae is a binary star system located around 310–316 light years away from the Sun in the northern constellation of Auriga. It is visible to the naked eye as a dim, white-hued star with a combined apparent visual magnitude of 5.83. This system is moving further from the Earth with a heliocentric radial velocity of 31 km/s. It is a probable member of the Hyades Supercluster.
Mu Boötis, Latinized from μ Boötis, consists of a pair of double stars in the northern constellation of Boötes, 120 light-years from the Sun.
38 Boötis is a single star in the northern constellation of Boötes, located approximately 157 light years from the Sun. It has the traditional name Merga and the Bayer designation h Boötis; 38 Boötis is the star's Flamsteed designation. This object is visible to the naked eye as a dim, yellow-white hued star with an apparent visual magnitude of 5.76. It is moving closer to the Earth with a heliocentric radial velocity of −4.5 km/s.
1 Boötis is a binary star system in the northern constellation of Boötes, located 318 light years away from the Sun. It is visible to the naked eye as a dim, white-hued star with a combined apparent visual magnitude of 5.71. The pair had an angular separation of 4.660″ as of 2008. It is moving closer to the Earth with a heliocentric radial velocity of −26 km/s.
Lambda Cancri is a blue-white-hued spectroscopic binary star in the zodiac constellation of Cancer. With a combined apparent visual magnitude of +5.93, it is faintly visible to the naked eye. Based upon parallax measurements obtained during the Gaia mission, it is about 550 light-years distant from the Sun.
Nu Capricorni or ν Capricorni is a binary star system in the southern constellation of Capricornus. It is visible to the naked eye with an apparent visual magnitude of +4.76.
λ Ophiuchi, Latinized as Lambda Ophiuchi, is a triple star system in the equatorial constellation of Ophiuchus. It has the traditional name Marfik, which now applies exclusively to the primary component. The system is visible to the naked eye as a faint point of light with an apparent visual magnitude of 3.82. It is located approximately 173 light-years from the Sun, based on its parallax, but is drifting closer with a radial velocity of –16 km/s.
Alpha2 Capricorni, or Algedi, is a triple star system in the southern constellation of Capricornus. It is visible to the naked eye with an apparent visual magnitude of +3.57. It is separated from the fainter α¹ Capricorni by 0.11° of the sky, a gap just resolvable with the naked eye, similar to Mizar and Alcor. Based on parallax shift as refined from orbits around the sun of the Gaia spacecraft at earth's Lagrange point 2, the star is 101 to 103 light years from the solar system.
HD 85951, formally named Felis, is a solitary orange hued star in the constellation Hydra. It has an apparent magnitude of 4.94, making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements, the object is about 570 light-years away from the Sun and is receding with a heliocentric radial velocity of 50 km/s.
Upsilon Pegasi, Latinised from υ Pegasi, is a star within the great square in the northern constellation of Pegasus. It has the proper name Alkarab. This object has a yellow-white hue and is faintly visible to the naked eye with an apparent magnitude of 4.40. It is located at a distance of approximately 170 light-years from the Sun based on parallax, but is drifting closer with a radial velocity of −8.6 km/s. The star is moving through the galaxy at a speed of 50.6 km/s relative to the Sun. Its projected galactic orbit carries it between 18,600 and 26,300 light-years from the center of the galaxy.
8 Draconis, formally named Taiyi, is a single star in the northern circumpolar constellation of Draco. Based upon an annual parallax shift of 34.14 mas as seen from the Earth, the star is located approximately 96 light-years from the Sun. It is moving further away with a heliocentric radial velocity of +9 km/s, having come within 40.6 ly some 2.6 million years ago.