Astronomy:Chi2 Fornacis

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Short description: Star in the constellation Fornax
χ2 Fornacis
Location of χ2 Fornacis (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Fornax
Right ascension  03h 27m 33.42119s[1]
Declination −35° 40′ 52.7728″[1]
Apparent magnitude (V) 5.70±0.01[2]
Characteristics
Spectral type K2 III[3]
B−V color index +1.29[4]
Variable type suspected[5]
Astrometry
Radial velocity (Rv)30.0±4.3[6] km/s
Proper motion (μ) RA: +77.064[1] mas/yr
Dec.: +5.989[1] mas/yr
Parallax (π)6.8558 ± 0.0446[1] mas
Distance476 ± 3 ly
(145.9 ± 0.9 pc)
Absolute magnitude (MV)0.00[7]
Details
Mass1.18[8] M
Radius23.58±1.19[9] R
Luminosity194+4−3[1] L
Surface gravity (log g)1.83[8] cgs
Temperature4,477±122[10] K
Metallicity [Fe/H]+0.02[11] dex
Rotational velocity (v sin i)<1.0[12] km/s
Other designations
χ2 For, NSV 15697, CD−36°1306, CPD−36°355, FK5 2244, GC 4129, HD 21574, HIP 16112, HR 1054, SAO 194312[13]
Database references
SIMBADdata

Chi2 Fornacis, Latinized from χ2 Fornacis, is a solitary star[14] located in the southern constellation Fornax, the furnace. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.70. Gaia DR3 parallax measurements imply a distance of 476 light-years and it is currently receding with a heliocentric radial velocity of approximately 30 km/s.[6] At its current distance, Chi2 Fornacis' brightness is diminished by an interstellar extinction of 0.11 magnitudes[15] and it has an absolute magnitude of 0.00.[7]

Chi2 Fornacis is an old-disk star[11] and it has a stellar classification of K2 III.[3] The class indicates that it is an evolved K-type giant that has ceased hydrogen fusion at its core and left the main sequence. It has 118% the mass of the Sun[8] but it has expanded to 23.58 times the radius of the Sun.[9] It radiates 194 time the luminosity of the Sun[1] from its photosphere at an effective temperature of 4,477 K.[10] Chi2 Fornacis is slightly metal enriched with a near-solar iron abundance of [Fe/H] = +0.02.[11] It spins too slowly for its projected rotational velocity to be measured accurately, having a projected rotational velocity lower than 1.0 km/s.[12]

The star was observed to be variable in infrared light during a 1991 IRAS survey for galaxy clusters.[16] However, its variability in optical light is unknown. In addition, subsequent observations have not confirmed the variability in infrared and optical light.[17] The lenticular galaxy NGC 1380 lies 2 degrees north-northeast of Chi2 Fornacis.[18]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode2000A&A...355L..27H. 
  3. 3.0 3.1 Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. 3. Bibcode1982mcts.book.....H. 
  4. Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99–110. Bibcode1966CoLPL...4...99J. 
  5. Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports 61 (1): 80–88. doi:10.1134/S1063772917010085. ISSN 1063-7729. Bibcode2017ARep...61...80S. 
  6. 6.0 6.1 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. ISSN 1063-7737. Bibcode2006AstL...32..759G. 
  7. 7.0 7.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode2012AstL...38..331A. 
  8. 8.0 8.1 8.2 Anders, F. et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics 628: A94. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode2019A&A...628A..94A. 
  9. 9.0 9.1 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (April 8, 2004). "The angular sizes of dwarf stars and subgiants: Surface brightness relations calibrated by interferometry". Astronomy & Astrophysics 426 (1): 297–307. doi:10.1051/0004-6361:20035930. ISSN 0004-6361. Bibcode2004A&A...426..297K. 
  10. 10.0 10.1 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode2019AJ....158..138S. 
  11. 11.0 11.1 11.2 Eggen, O. J. (July 1993). "Evolved GK stars near the sun. I - The old disk population". The Astronomical Journal 106: 80. doi:10.1086/116622. Bibcode1993AJ....106...80E. 
  12. 12.0 12.1 De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars V: Southern stars *". Astronomy & Astrophysics 561: A126. doi:10.1051/0004-6361/201220762. ISSN 0004-6361. Bibcode2014A&A...561A.126D. 
  13. "Chi02 For". https://simbad.cds.unistra.fr/mobile/object.html?object_name=HD+21574. 
  14. Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869–879. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. Bibcode2008MNRAS.389..869E. 
  15. Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society 472 (4): 3805–3820. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode2017MNRAS.472.3805G. 
  16. Wang, G.; Clowes, R. G.; Leggett, S. K.; MacGillivray, H. T.; Savage, A. (1991). "Optical identifications of IRAS point sources: the Fornax, Hydra I and Coma clusters". Monthly Notices of the Royal Astronomical Society 248 (1): 112–127. doi:10.1093/mnras/248.1.112. ISSN 0035-8711. Bibcode1991MNRAS.248..112W. 
  17. Samus, N. N.; Durlevich, O. V. (November 2004). "VizieR Online Data Catalog: Combined General Catalogue of Variable Stars (Samus+ 2004)". VizieR Online Data Catalog: II/250. Bibcode2004yCat.2250....0S. 
  18. O'Meara, Stephen James (2013). Deep-Sky Companions: Southern Gems. Cambridge University Press. pp. 78–80. ISBN 9781107015012. Bibcode2013dcsg.book.....O. https://books.google.com/books?id=S5QIEKns33sC&pg=PA78. 
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