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Tau Octantis

τ Octantis
Location of τ Octantis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Octans
Right ascension 23h 28m 03.7855s[1]
Declination −87° 28′ 55.967″[1]
Apparent magnitude (V) 5.50[2]
Characteristics
Spectral type K2 III[3]
U−B color index +1.43[4]
B−V color index +1.27[4]
Astrometry
Radial velocity (Rv)31.0±1.4[5] km/s
Proper motion (μ) RA: +16.782 mas/yr[1]
Dec.: +11.957 mas/yr[1]
Parallax (π)6.8009 ± 0.0574 mas[1]
Distance480 ± 4 ly
(147 ± 1 pc)
Absolute magnitude (MV)−0.36[2]
Details
Mass1.14[6] M☉
Radius24[7] R☉
Luminosity223[8] L☉
Surface gravity (log g)1.63[6] cgs
Temperature4,422[8] K
Metallicity [Fe/H]+0.12[9] dex
Rotational velocity (v sin i)<1[10] km/s
Other designations
τ Oct, 81 G. Octantis, CPD−88°204, FK5 925, GC 32558, HD 219765, HIP 115836, HR 8862, SAO 258970
Database references
SIMBADdata

Tau Octantis, Latinized from τ Octantis, is a solitary[11] star in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.50,[2] allowing it to be faintly seen with the naked eye. The object is located at a distance of 480 light years[1] but is receding with a heliocentric radial velocity of 31 km/s.[5]

Tau Octantis has a stellar classification of K2 III, indicating that the object is a red giant. It has 114% the mass of the Sun[6] but is 223 times as luminous.[8] However, an enlarged radius of 24 R☉ yields an effective temperature of 4,422 K,[8] giving it an orange glow. Tau Octantis has an iron abundance 132% that of the Sun and is believed to be a member of the old disk population.[9] Currently, it spins with a projected rotational velocity less than 1 km/s.[10]

  1. ^ a b c d e Cite error: The named reference EDR3 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Houk1975 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference Anders2019 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference ticv8 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference McDonald2012 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Eggen1993 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference DeMederios2014 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Eggelton2008 was invoked but never defined (see the help page).
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