HIP 12961

HIP 12961 / Koeia
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Eridanus
Right ascension 02h 46m 42.8869s[1]
Declination −23° 05′ 11.802″[1]
Apparent magnitude (V) 10.24[2]
Characteristics
Spectral type K5V[3] or M0[4]
Apparent magnitude (B) 11.20[2]
Apparent magnitude (J) 7.56[2]
Apparent magnitude (H) 6.93[2]
Apparent magnitude (K) 6.74[2]
B−V color index 1.6
Astrometry
Radial velocity (Rv)+32.865±0.001[5] km/s
Proper motion (μ) RA: 294.717(11) mas/yr[1]
Dec.: 140.966(15) mas/yr[1]
Parallax (π)42.6929 ± 0.0141 mas[1]
Distance76.40 ± 0.03 ly
(23.423 ± 0.008 pc)
Absolute magnitude (MV)8.50±0.09[4]
Details
Mass0.64 M☉[6]
0.65±0.07[4] M☉
Radius0.63 R☉[6]
0.61±0.04[4] R☉
Luminosity0.095±0.018[4] L☉
Surface gravity (log g)4.65±0.09[7] cgs
Temperature3,901±175 K[7]4,092±93[4] K
Metallicity [Fe/H]+0.10±0.06 dex[6]
−0.14 dex[7]0.01±0.17[8] dex
Rotational velocity (v sin i)1.5[6] km/s
Other designations
Koeia, CD−23 1056, HIP 12961, SAO 168043, PPM 245393, LTT 1349, NLTT 8966, TYC 6434-00494-1, 2MASS J02464286-2305119[9]
Database references
SIMBADdata
Exoplanet Archivedata

HIP 12961 is a star with an exoplanetary companion in the equatorial constellation of Eridanus. It is too faint to be visible to the naked eye, with an apparent visual magnitude of 10.24.[2] The distance to this system can be estimated from its parallax measurements, which yield a separation of 76.4 light-years from the Sun. It is receding with a radial velocity of +33 km/s[5] and has a high proper motion, traversing the celestial sphere at an angular rate of 0.300″ yr−1.[2]

This was classified as a cool red dwarf star of stellar classification M0 in 1980,[4] while C. B. Stephenson graded it as class K5V in 1986.[3] The absolute magnitude and color index of this star is a closer match to the former. It shows a high chromospheric activity level[4] and is one of the largest and brightest M class red dwarf stars known, with 64% of the mass and 63% of the radius of the Sun.[6] The star is radiating 10% of the luminosity of the Sun from its photosphere at an effective temperature of 4,092 K.[4]

HIP 12961 is named Koeia. The name was selected in the NameExoWorlds campaign by Puerto Rico, during the 100th anniversary of the IAU. Koeia was the word for star in the language of the Taíno Indigenous People of the Caribbean.[10][11]

  1. ^ a b c d Cite error: The named reference Gaia DR3 was invoked but never defined (see the help page).
  2. ^ a b c d e f g Cite error: The named reference Winters_et_al_2015 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Stephenson1986 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h i Cite error: The named reference Gaidos_et_al_2014 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Soubiran_et_al_2018 was invoked but never defined (see the help page).
  6. ^ a b c d e Cite error: The named reference Lindgren2017 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference Stassun_et_al_2016 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference apj748_2_934 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 NameExoworlds was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference IAU was invoked but never defined (see the help page).