Theta Octantis

Theta Octantis
Location of θ Octantis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Octans
Right ascension 00h 01m 35.70158s[1]
Declination −77° 03′ 56.6092″[1]
Apparent magnitude (V) 4.78[2]
Characteristics
Spectral type K3III[3]
U−B color index +1.41[4]
B−V color index +1.27[4]
Astrometry
Radial velocity (Rv)+22.48±0.17[5] km/s
Proper motion (μ) RA: −57.30[1] mas/yr
Dec.: −177.06[1] mas/yr
Parallax (π)15.02 ± 0.18 mas[1]
Distance217 ± 3 ly
(66.6 ± 0.8 pc)
Absolute magnitude (MV)0.66[2]
Details
Mass1.20[6] M☉
Radius15.84+0.42
−1.02[5] R☉
Luminosity79.2±1.5[5] L☉
Surface gravity (log g)2.16[6] cgs
Temperature4,325+147
−55[5] K
Rotational velocity (v sin i)< 1.0[7] km/s
Other designations
θ Oct, CPD−77° 1596, FK5 904, GC 33321, HD 224889, HIP 122, HR 9084, SAO 258207[8]
Database references
SIMBADdata

θ Octantis, Latinized as Theta Octantis, is a single[9] star in the southern circumpolar constellation of Octans, near the constellation border with Hydrus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.78.[2] The star is located approximately 217 light years from the Sun based on parallax,[1] and is drifting further away with a radial velocity of +22.5 km/s.[5]

This is an aging giant star with a stellar classification of K3III,[3] having exhausted the supply of hydrogen at its core then cooled and expanded. It has been catalogued as a red clump giant,[10] which would indicate it is on the horizontal branch and is undergoing core helium fusion. At present it has 16[5] times the radius of the Sun. This star has 1.20[6] times the mass of the Sun and is radiating 79[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,325 K.[5]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference XHIP was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference houk1979 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 c d e f g h Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference AllendePrieto was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference deMedeiros2014 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 Eggleton2008 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Gontcharov2008 was invoked but never defined (see the help page).