Alpha Horologii

Alpha Horologii
Observation data
Epoch J2000      Equinox J2000
Constellation Horologium
Right ascension 04h 14m 00.114s[1]
Declination −42° 17′ 39.727″ [1]
Apparent magnitude (V) +3.846[2]
Characteristics
Evolutionary stage Giant star
Spectral type K2 III[3]
U−B color index +1.013[4]
B−V color index 1.083±0.037[2]
Astrometry
Radial velocity (Rv)+21.6±0.3[5] km/s
Proper motion (μ) RA: +41.992±0.125 mas/yr[1]
Dec.: −203.157±0.154 mas/yr[1]
Parallax (π)27.721 ± 0.11195 mas[1]
Distance117.6+0.55
−0.52 ly
(36.06+0.17
−0.16 pc)[6]
Absolute bolometric
magnitude (Mbol)		+1.08[7]
Details[2]
Mass1.409±0.265 M☉
Radius9.931±0.351 R☉
Luminosity37.61[8] L☉
Surface gravity (log g)2.82±0.02 cgs
Temperature4695±50 K
Metallicity [Fe/H]−0.03±0.03 dex
Age3.561±2.333 Gyr
Other designations
α Hor, CD−42° 1425, HD 26967, HIP 19747, HR 1326, SAO 216710[9]
Database references
SIMBADdata

Alpha Horologii (α Horologii) is a solitary[10] orange-hued giant star and the brightest star in the constellation Horologium. It is visible to the naked eye with an apparent visual magnitude of +3.85.[2] Based upon an parallax shift of 27.721 mas as seen from the Earth, it is located at a distance of 36 light-years (11 parsecs).[1] The star is moving away from the Sun with a radial velocity of +21.6 km/s.[5]

The stellar classification of K2 III[3] indicates this is an evolved giant star of the K class. This means it has consumed the hydrogen at its core and has migrated away from the main sequence, with its outer envelope cooling and expanding in the process. Alpha Horologii has an estimated 1.41 times the mass of the Sun[2] and is radiating 38[8] times the Sun's luminosity from its photosphere at an effective temperature of 4,695 K.[2] Being 3.56 billion years old, it has swollen to around 10 times the diameter of the Sun,[2] having spent much of its life as a white main sequence star.[11]

  1. ^ a b c d e Cite error: The named reference DR3 was invoked but never defined (see the help page).
  2. ^ a b c d e f g Cite error: The named reference Gomes2021 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Gray2006 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Cousins1973 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference b-j was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Liu 2007 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Mcdonald was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD 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. ^ Kaler, Jim. "Alpha Horologii". James Kaler's Stars. Retrieved 20 September 2019.