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HD 21278

HD 21278
Location of HD 21278 (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Perseus
Right ascension 03h 28m 03.07229s[1]
Declination 49° 03′ 46.3315″[1]
Apparent magnitude (V) 4.99[2]
Characteristics
Spectral type B5V[3]
U−B color index −0.56[4]
B−V color index −0.10[4]
Astrometry
Radial velocity (Rv)+1.20[5] km/s
Proper motion (μ) RA: +21.784[1] mas/yr
Dec.: −26.036[1] mas/yr
Parallax (π)5.6334 ± 0.2298 mas[1]
Distance580 ± 20 ly
(178 ± 7 pc)
Absolute magnitude (MV)−1.49[6]
Orbit[7]
Period (P)21.695±0.004 d
Semi-major axis (a)≥6.72 Gm
Eccentricity (e)0.12±0.04
Periastron epoch (T)24,446,714.5±0.2
Argument of periastron (ω)
(secondary)		109±3°
Semi-amplitude (K1)
(primary)		22.7±0.9 km/s
Semi-amplitude (K2)
(secondary)		49±3 km/s
Details
A
Mass4.597[8] M☉
Radius3.9[9] R☉
Luminosity940[6] L☉
Surface gravity (log g)4.152±0.113[10] cgs
Temperature15,274±244[10] K
Metallicity [Fe/H]0.00[11] dex
Rotational velocity (v sin i)75[10] km/s
Age187[11] or 60[6] Myr
Other designations
BD+48°920, GC 4108, HD 21278, HIP 16147, HR 1034, SAO 38849[12]
Database references
SIMBADdata

HD 21278 is a binary star[7] system in the constellation Perseus, located within the 60±7[6] million year old Alpha Persei Cluster.[7] It has a blue-white hue and is visible to the naked eye with a combined apparent visual magnitude of 4.99.[2] The system is located at a distance of approximately 580 light years from the Sun based on parallax,[1] and it is drifting further away with a radial velocity of +1.20 km/s.[5]

The binary nature of this star was announced in 1925 by Otto Struve.[13] It is a double-lined spectroscopic binary with an orbital period of 21.7 days and an eccentricity of 0.12.[7]

The primary component is a B-type main-sequence star with a stellar classification of B5V,[3] indicating it is generating energy through core hydrogen fusion. The star is spinning with a projected rotational velocity of 75 km/s.[10] It has 4.6[8] times the mass of the Sun and about 3.9[9] times the Sun's radius. HD 21278 is radiating 940[6] times the luminosity of the Sun from its photosphere at an effective temperature of 15,274 K.[10]

  1. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference XHIP was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Zuckerman2012 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Mallama2014 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Pourbaiz2004 was invoked but never defined (see the help page).
  6. ^ a b c d e Cite error: The named reference Silaj2014 was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference Morrell1992 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Sheikhi2016 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference CADARS was invoked but never defined (see the help page).
  10. ^ a b c d e Cite error: The named reference David2015 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference Gontcharov2012 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Struve1925 was invoked but never defined (see the help page).
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