Astronomy:HD 204904

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Short description: Spectroscopic binary in the constellation Octans
HD 204904
Octans constellation map.svg
Red circle.svg
Location of HD 204904 on the map (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Octans
Right ascension  21h 38m 56.38010s[1]
Declination −79° 26′ 33.2989″[1]
Apparent magnitude (V) 6.17±0.01[2]
Characteristics
Spectral type F6 IV[3] or F4 IV[4]
U−B color index +0.02[5]
B−V color index +0.46[5]
Astrometry
Radial velocity (Rv)−5.2±0.5[6] km/s
Proper motion (μ) RA: +71.185[1] mas/yr
Dec.: −26.928[1] mas/yr
Parallax (π)15.369 ± 0.0195[1] mas
Distance212.2 ± 0.3 ly
(65.07 ± 0.08 pc)
Absolute magnitude (MV)+2.13[7]
Details
Mass1.53[8] M☉
Radius2.87±0.15[9] R☉
Luminosity12.1±0.1[1] L☉
Surface gravity (log g)3.67+0.10−0.09[10] cgs
Temperature6,443±80[11] K
Metallicity [Fe/H]−0.20±0.06[12] dex
Rotational velocity (v sin i)12±1.6[13] km/s
Age2.56[8] Gyr
Other designations
CD−79°856, CPD−79°1158, FK5 3723, GC 30221, HD 204904, HIP 106881, HR 8234, SAO 257942[14]
Database references
SIMBADdata

HD 204904 (HR 8234; 59 G. Octantis) is a spectroscopic binary located in the southern circumpolar constellation Octans. It has an apparent magnitude of 6.17,[2] placing it near the limit for naked eye visibility, even under ideal conditions. The object is located relatively close at distance of 212 light-years based on Gaia DR3 parallax measurements[1] and it is drifting closer with a heliocentric radial velocity of −5.2 km/s.[6] At its current distance, HD 204904's brightness is diminished by 0.19 magnitudes due to interstellar extinction[15] and it has an absolute magnitude of +2.13.[7]

HD 204904 has a stellar classification of either F6 IV or F4 IV,[4] indicating that it is a slightly evolved F-type subgiant. It has 1.53 times the mass of the Sun[8] and a slightly enlarged radius 2.87 times that of the Sun's.[9] It radiates 12.1 times the luminosity of the Sun[1] from its photosphere at an effective temperature of 6,443 K,[11] giving it the typical yellowish-white hue of an F-type star. HD 204904 is metal deficient with an iron abundance of [Fe/H] = −0.20 or 63.1% of the Sun's iron abundance.[12] It is estimated to be 2.56 billion years old[8] and it spins modestly with a projected rotational velocity of 12 km/s.[13]

In 2014, J. R. De Medeiros and colleagues detected radial velocity variations from the star, indicating that it was a spectroscopic binary.[13] However, the system does not have a defined orbit.[16]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 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. ↑ 2.0 2.1 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. Bibcode: 2000A&A...355L..27H. 
  3. ↑ Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars: Declinations −90° to −53°. 1. Bibcode: 1975mcts.book.....H. 
  4. ↑ 4.0 4.1 Malaroda, S. (August 1975). "Study of the F-Type Stars I: MK spectral types.". The Astronomical Journal 80: 637. doi:10.1086/111786. ISSN 0004-6256. Bibcode: 1975AJ.....80..637M. 
  5. ↑ 5.0 5.1 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. Bibcode: 1966CoLPL...4...99J. 
  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. Bibcode: 2006AstL...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. Bibcode: 2012AstL...38..331A. 
  8. ↑ 8.0 8.1 8.2 8.3 David, Trevor J.; Hillenbrand, Lynne A. (12 May 2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal 804 (2): 146. doi:10.1088/0004-637X/804/2/146. Bibcode: 2015ApJ...804..146D. 
  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. Bibcode: 2004A&A...426..297K. 
  10. ↑ 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. Bibcode: 2019AJ....158..138S. 
  11. ↑ 11.0 11.1 Casagrande, L.; Schönrich, R.; Asplund, M.; Cassisi, S.; Ramírez, I.; Meléndez, J.; Bensby, T.; Feltzing, S. (26 May 2011). "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s): Improved astrophysical parameters for the Geneva-Copenhagen Survey⋆". Astronomy & Astrophysics 530: A138. doi:10.1051/0004-6361/201016276. ISSN 0004-6361. Bibcode: 2011A&A...530A.138C. 
  12. ↑ 12.0 12.1 Netopil, Martin (4 May 2017). "Metallicity calibrations for dwarf stars and giants in the Geneva photometric system". Monthly Notices of the Royal Astronomical Society 469 (3): 3042–3055. doi:10.1093/mnras/stx1077. ISSN 0035-8711. Bibcode: 2017MNRAS.469.3042N. 
  13. ↑ 13.0 13.1 13.2 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. Bibcode: 2014A&A...561A.126D. 
  14. ↑ "HD 204904". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+204904. 
  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. Bibcode: 2017MNRAS.472.3805G. 
  16. ↑ Tokovinin, Andrei (14 March 2014). "From Binaries to Multiples. I. Data on F and G Dwarfs within 67 pc of the Sun". The Astronomical Journal 147 (4): 86. doi:10.1088/0004-6256/147/4/86. ISSN 0004-6256. Bibcode: 2014AJ....147...86T. 
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