Zeta Octantis

ζ Octantis
Location of ζ Octantis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Octans
Right ascension 08h 56m 40.97572s[1]
Declination −85° 39′ 47.3476″[1]
Apparent magnitude (V) 5.42±0.01[2]
Characteristics
Spectral type A8/9 IV[3] or F0 III[4]
U−B color index +0.07[5]
B−V color index +0.31[5]
Astrometry
Radial velocity (Rv)−3.6±2[6] km/s
Proper motion (μ) RA: −117.699 mas/yr[1]
Dec.: +33.964 mas/yr[1]
Parallax (π)20.9964 ± 0.0776 mas[1]
Distance155.3 ± 0.6 ly
(47.6 ± 0.2 pc)
Absolute magnitude (MV)+1.95[7]
Details
Mass2.06±0.40[8] M☉
Radius2.25±0.11[9] R☉
Luminosity12.63±0.09[1] L☉
Surface gravity (log g)4.04±0.28[8] cgs
Temperature7,063±325[10] K
Metallicity [Fe/H]−0.36[11] dex
Rotational velocity (v sin i)115[12] km/s
Age1.25[13] Gyr
Other designations
ζ Oct, 9 G. Octantis[14], CPD−85°183, FK5 918, GC 12580, HD 79837, HIP 43908, HR 3678, SAO 258515[15]
Database references
SIMBADdata

Zeta Octantis, Latinized from ζ Octantis, is a solitary,[16] yellowish-white hued star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.42,[2] making it faintly visible to the naked eye under ideal conditions. The star is located relatively close at a distance of only 156 light-years based on Gaia DR3 parallax measurements,[1] but is drifting closer with a radial velocity of −3.6 km/s.[6] At its current distance, Zeta Octantis' brightness is diminished by 0.25 magnitudes due to interstellar dust.[17]

This s an evolved A-type star with a stellar classification of A8/9 IV.[3] David S. Evans and colleagues, however, give it a classification of F0 III,[4] which suggests it is already an evolved giant star. It has double the Sun's mass,[8] and 2.25 times the Sun's radius.[9] It radiates around 13 times the luminosity of the Sun[1] from its photosphere at an effective temperature of 7,063 K.[10] Zeta Octantis is estimated to be 1.25 billion years olds based on stellar evolution models by Trevor J. David and Lynne A. Hillenbrand.[13] It has a low metallicity, having only 44% the abundance of heavy metals compared to the Sun.[11] Despite its advanced age, the object spins rapidly with a projected rotational velocity of 115 km/s,[12] resulting in an oblate shape with a equatorial bulge 11% larger than the polar radius.[18]

  1. ^ a b c d e f g Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Tycho2000 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Houk1975 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Evans1959 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Mall2014 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Evans1967 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference XHIP was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference Stassun2018 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Kervella2004 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Bai2019 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference Netopil2017 was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference Huang1953 was invoked but never defined (see the help page).
  13. ^ a b Cite error: The named reference David2015 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Gould1879 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Gontcharov2017 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference van Belle2012 was invoked but never defined (see the help page).