21 Aquilae

21 Aquilae

An ultraviolet band light curve for V1288 Aquilae, adapted from Veto (1980)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 13m 42.70120s[2]
Declination +02° 17′ 37.3103″[2]
Apparent magnitude (V) 5.06 - 5.16[3]
Characteristics
Spectral type B8II-III(Hg?)[4]
U−B color index −0.399[5]
B−V color index −0.065[5]
Variable type α2 CVn[3]
Astrometry
Radial velocity (Rv)−5.2[6] km/s
Proper motion (μ) RA: +10.102[2] mas/yr
Dec.: −0.825[2] mas/yr
Parallax (π)4.7730 ± 0.1052 mas[2]
Distance680 ± 20 ly
(210 ± 5 pc)
Absolute magnitude (MV)−2.12[7]
Details
Mass6.7[8] M☉
Radius6.2[9] R☉
Luminosity704[8] L☉
Surface gravity (log g)3.95[8] cgs
Temperature12,014[8] K
Metallicity [Fe/H]−0.20[10] dex
Rotation9.3 d[11]
Rotational velocity (v sin i)17[10] km/s
Age165[12] Myr
Other designations
21 Aql, V1288 Aql, BD+02°3824, FK5 3537, HD 179761, HIP 94477, HR 7287, SAO 124408, WDS J19137+0218A[13]
Database references
SIMBADdata

21 Aquilae is a solitary[14] variable star in the equatorial constellation of Aquila. It has the variable star designation V1288 Aql; 21 Aquilae is its Flamsteed designation. This object is visible to the naked eye as a dim, blue-white hued star with a baseline apparent visual magnitude of about 5.1. The star is located at a distance of around 680 light-years (210 parsecs) from Earth, give or take a 20 light-year margin of error. It is moving closer to the Earth with a heliocentric radial velocity of –5 km/s.[6]

The stellar classification of this star is B8 II-III, with the luminosity class of II-III suggesting that the spectrum displays elements of both a giant star and a bright giant. It is a chemically peculiar star of the Mercury-Manganese type (CP3),[10] although some catalogues consider that status to be doubtful.[15] This is a probable Alpha2 Canum Venaticorum variable that ranges in visual magnitude from 5.06 down to 5.16.[3] The star is radiating 704 times the luminosity of the Sun from its photosphere at an effective temperature of 12,014 K; this gives it the blue-white glow of a B-type star.[16]

21 Aquilae is catalogued as an optical double star, having a 12th magnitude companion 37″ away as of 2010. It was first identified as a double star by John Herschel.[17] The companion is a distant background object.[18]

  1. ^ Cite error: The named reference veto1980 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference cowley1972 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference apj154_945 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference rgcrv was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference fouesneau2022 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference kervella2021 was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference Ghazaryan2018 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference oelkers2018 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference gontcharov2012 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference renson2009 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference wds was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference dr3b was invoked but never defined (see the help page).