Eta2 Pictoris

η2 Pictoris, Latinised as Eta2 Pictoris, is a solitary[8] star in the southern constellation of Pictor. It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.02.[2] With an annual parallax shift of 7.8 mas as seen from the Earth,[1] it is located around 418 light years from the Sun. It is a member of the HR 1614 moving group of stars that share a common motion through space.[6]

For other stars with this Bayer designation, see η Pictoris.
Eta2 Pictoris
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Pictor
Right ascension  05h 04m 58.01433s[1]
Declination −49° 34′ 40.2034″[1]
Apparent magnitude (V) 5.02[2]
Characteristics
Spectral type K5 III[3]
U−B color index +1.82[2]
B−V color index +1.51[2]
Variable type suspected[4]
Astrometry
Radial velocity (Rv)−5.0±7.4[5] km/s
Proper motion (μ) RA: +68.538[1] mas/yr
Dec.: −2.186[1] mas/yr
Parallax (π)7.8033 ± 0.1351[1] mas
Distance418 ± 7 ly
(128 ± 2 pc)
Absolute magnitude (MV)−1.2[6]
Details
Radius40.56+0.59
−2.38[1] R☉
Luminosity362.6±7.4[1] L☉
Temperature3,955+121
−28[1] K
Other designations
η2 Pic, NSV 1827, CD−49°1562, FK5 187, GC 6234, HD 33042, HIP 23649, HR 1663, SAO 217164[7]
Database references
SIMBADdata

This is an evolved K-type giant star with a stellar classification of K5 III,[3] having exhausted the supply of hydrogen at its core, then cooled and expanded off the main sequence. At present it has 41[1] times the girth of the Sun. It is radiating an estimated 363.5 times the Sun's luminosity from its photosphere at an effective temperature of 4,136 K.[9] This is a member of the old disk population and is a suspected variable star.[10]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Cousins, A. W. J.; et al. (1969), "Comparison Stars for Long Period Variables", Monthly Notes of the Astronomical Society of Southern Africa, 28: 63, Bibcode:1969MNSSA..28...63C.
  3. Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Ann Arbor: Department of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  6. Eggen, Olin J. (October 1996), "Star Streams and Galactic Structure", Astronomical Journal, 112: 1595, Bibcode:1996AJ....112.1595E, doi:10.1086/118126.
  7. "* eta02 Pic". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-22.
  8. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  9. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  10. Eggen, O. J. (1973), "The classification of intrinsic variables. IV. Very-small-amplitude, very-short-period red variables", Astrophysical Journal, 184: 793, Bibcode:1973ApJ...184..793E, doi:10.1086/152371.
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