Alruba

Alruba
Location of Alruba (circled)
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]
Distance457 ± 4 ly
(140 ± 1 pc)
Details
Mass2.97±0.07[3] M☉
Luminosity146.7+29.6
−24.7[3] L☉
Surface gravity (log g)3.80±0.10[6] cgs
Temperature9,226+107
−106[3] K
Metallicity [Fe/H]−0.40±0.11[6] dex
Rotational velocity (v sin i)170[3] km/s
Age58[7] Myr
Other designations
Alruba, BD+53°1978, CPD–51°9815, HD 161693, HIP 86782, HR 6618, SAO 30538[8]
Database references
SIMBADdata

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]

  1. ^ a b c d e Cite error: The named reference dr2 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference ubv was invoked but never defined (see the help page).
  3. ^ a b c d e f g h i Cite error: The named reference zorec2012 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference abt was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference pulkovo was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Wu2011 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference gullikson was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference IAU-LSN was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Schröder2007 was invoked but never defined (see the help page).