HD 169904
Location of HD 204904 on the map (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Octans
Right ascension 18h 42m 14.42015s[1]
Declination −81° 48′ 29.2064″[1]
Apparent magnitude (V) 6.26±0.01[2]
Characteristics
Evolutionary stage main sequence star[3]
Spectral type B8 V[4]
U−B color index −0.37[5]
B−V color index −0.13[5]
Variable type suspected[6]
Astrometry
Radial velocity (Rv)−6.0±4.3[7] km/s
Proper motion (μ) RA: +13.838 mas/yr[1]
Dec.: −16.605 mas/yr[1]
Parallax (π)6.7598 ± 0.0413 mas[1]
Distance482 ± 3 ly
(147.9 ± 0.9 pc)
Absolute magnitude (MV)+0.19[8]
Details
Mass3.25±0.06[3] M☉
Radius2.42±0.12[9] R☉
Luminosity141+14
−13[3] L☉
Surface gravity (log g)4.20[10] cgs
Temperature13,622[11] K
Metallicity [Fe/H]−0.18[12] dex
Rotational velocity (v sin i)123[13] km/s
Other designations
35 G. Octantis[14], NSV 24510, CD−81°693, CPD−81°813, GC 25366, HD 169904, HIP 91723, HR 6912, SAO 258804, TIC 351920521[15]
Database references
SIMBADdata

HD 169904 (HR 6912; 35 G. Octantis) is a solitary star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 6.26,[2] placing it near the limit for naked eye visibility, even under ideal conditions. Gaia DR3 parallax measurements imply a distance of 482 light-years[1] and it is currently drifting closer with a somewhat constrained radial velocity of −6.0 km/s.[7] At its current distance, HD 169904's brightness is diminished by 0.24 magnitudes due to interstellar extinction[16] and it has an absolute magnitude of +0.19.[8]

HD 169904 has a stellar classification of B8 V,[4] indicating that it is an ordinary B-type main-sequence star that is generating energy via hydrogen fusion at its core. It has 3.25 times the mass of the Sun[3] and 2.42 times the radius of the Sun.[9] It radiates 141 times the luminosity of the Sun[3] from its photosphere at an effective temperature of 13,622 K,[11] giving it a blue-white hue when viewed in the night sky. HD 169904 is metal deficient with an iron abundance of [Fe/H] = −0.18 or 66.1% of the Sun's,[12] and it spins rapidly with a projected rotational velocity of 123 km/s.[13] HD 169904 is estimated to have completed 47.5% of its main sequence lifetime.[3]

The object was listed as a suspected variable star based on photometric observations,[6] but subsequent observations have not confirmed this.[17]

References

  1. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361. S2CID 17128864.
  3. 1 2 3 4 5 6 Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars IV: Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. eISSN 1432-0746. ISSN 0004-6361. S2CID 55586789.
  4. 1 2 Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars: Declinations −90° to −53°. Vol. 1. Bibcode:1975mcts.book.....H.
  5. 1 2 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. 1 2 Grønbech, B.; Olsen, E. H. (July 1976). "Four-color uvby photometry for bright O to G0 type stars south of declination +10 ". Astronomy and Astrophysics Supplement Series. 25: 213–270. Bibcode:1976A&AS...25..213G. ISSN 0365-0138. S2CID 118304388.
  7. 1 2 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. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
  8. 1 2 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
  9. 1 2 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. arXiv:astro-ph/0404180. Bibcode:2004A&A...426..297K. doi:10.1051/0004-6361:20035930. eISSN 1432-0746. ISSN 0004-6361.
  10. ↑ McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017). "Fundamental parameters and infrared excesses of Tycho–Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770–791. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. eISSN 1365-2966. ISSN 0035-8711. S2CID 73594365.
  11. 1 2 Philip, A. G. D.; Egret, D. (May 1980). "An analysis of the Hauck-Mermillod catalogue of homogeneous four-color data. II". Astronomy and Astrophysics Supplement Series. 40: 199–205. Bibcode:1980A&AS...40..199P. ISSN 0365-0138.
  12. 1 2 Anders, F.; et al. (February 2022). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia EDR3 stars brighter than G = 18.5". Astronomy & Astrophysics. 658: A91. arXiv:2111.01860. Bibcode:2022A&A...658A..91A. doi:10.1051/0004-6361/202142369. eISSN 1432-0746. ISSN 0004-6361.
  13. 1 2 Levato, Hugo; Grosso, Mónica (June 2004). "New Projected Rotational Velocities of All Southern B-type Stars of the Bright Star Catalogue". Symposium - International Astronomical Union. 215: 51–52. Bibcode:2004IAUS..215...51L. doi:10.1017/S0074180900195191. ISSN 0074-1809.
  14. ↑ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
  15. ↑ "HD 169904". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 4, 2023.
  16. ↑ 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. arXiv:1709.01160. Bibcode:2017MNRAS.472.3805G. doi:10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711. S2CID 118879856.
  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. Bibcode:2004yCat.2250....0S.
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