Pi Fornacis

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Pi Fornacis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Fornax
Right ascension 02h 01m 14.72272s[1]
Declination −30° 00′ 06.5913″[1]
Apparent magnitude (V) 5.360[2]
Spectral type G8 III[3]
U−B color index +0.471[2]
B−V color index +0.882[2]
Radial velocity (Rv)24.40±0.10[4] km/s
Proper motion (μ) RA: −109.37[1] mas/yr
Dec.: −109.19[1] mas/yr
Parallax (π)11.08 ± 0.29[1] mas
Distance294 ± 8 ly
(90 ± 2 pc)
Absolute magnitude (MV)+0.68[5]
π For A
Mass1.04±0.22 M
Radius9.62±0.44 R
Luminosity57.5 L
Surface gravity (log g)2.75±0.05 cgs
Temperature5,048±26 K
Metallicity [Fe/H]−0.56±0.03 dex
Rotational velocity (v sin i)0.92±0.44 km/s
Age5.18±3.05 Gyr
π For B
Mass0.5[6] M
Other designations
π For, CD−30° 703, HD 12438, HIP 9440, HR 594, SAO 193455.[7]
Database references

π Fornacis (Latinised as Pi Fornacis) is the Bayer designation for a binary star system in the southern constellation of Fornax. It has an apparent visual magnitude of 5.360,[2] which is bright enough to be seen with the naked eye on a dark night. With an annual parallax shift of 11.08 mas, it is estimated to lie around 294 light years from the Sun. At that distance, the visual magnitude is diminished by an interstellar absorption factor of 0.10 due to dust.[4]

This system is a member of the thin disk population of the Milky Way galaxy.[4] The primary, component A, is an evolved G-type giant star with a stellar classification of G8 III.[3] It has an estimated mass slightly higher than the Sun, but has expanded to more than nine times the Sun's radius. The star is roughly five billion years old and is spinning slowly with a projected rotational velocity of 0.9 km/s. Pi Fornacis A radiates 57.5 times the solar luminosity from its outer atmosphere at an effective temperature of 5,048 K.[4]

A companion, component B, was discovered in 2008 using the AMBER instrument of the Very Large Telescope facility. At the time of discovery, this star lay at an estimated angular separation of 12.0±4.0 mas from the primary along a position angle of 120°±20°. The preliminary orbital period for the pair is 11.4 years, and the semimajor axis is at least 70 mas. The orbit is highly inclined to the line of sight from the Earth.[6]


  1. ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ^ a b c d Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society, 172: 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
  3. ^ a b Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H
  4. ^ a b c d e Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, A50.
  5. ^ Ammler-von Eiff, M.; Reiners, A. (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724.
  6. ^ a b Cusano, F.; et al. (March 2012), "AMBER/VLTI observations of five giant stars", Astronomy & Astrophysics, 539: 7, arXiv:1112.5043, Bibcode:2012A&A...539A..58C, doi:10.1051/0004-6361/201116731, A58.
  7. ^ "pi. For -- High proper-motion Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-01-24.