HD 92845

HD 92845 (HR 4194) is a probable astrometric binary[15] in the southern constellation Antlia. It has an apparent magnitude of 5.62, allowing it to be faintly seen with the naked eye. Parallax measurements place the system at a distance of 790 light years and it is currently receding with a heliocentric radial velocity of 4.5 km/s.

HD 92845
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Antlia
Right ascension 10h 42m 43.1844s[1]
Declination −32° 42′ 56.413″[1]
Apparent magnitude (V) 5.62±0.01[2]
Characteristics
Evolutionary stage subgiant[3]
Spectral type A0 V[4]
B−V color index +0.00[5]
Astrometry
Radial velocity (Rv)4.5±0.5[6] km/s
Proper motion (μ) RA: −28.903 mas/yr[1]
Dec.: +1.262 mas/yr[1]
Parallax (π)4.1113 ± 0.2655 mas[1]
Distance790 ± 50 ly
(240 ± 20 pc)
Absolute magnitude (MV)−0.67[7]
Details
Mass3.1±0.1[3] M☉
Radius5.31[8] R☉
Luminosity206+72
−53[3] L☉
Surface gravity (log g)3.5[9] cgs
Temperature9,376±109[8] K
Metallicity [Fe/H]0.00[10] dex
Rotational velocity (v sin i)81±3[11] km/s
Age282±34[12] Myr
Other designations
78 G. Antilae[13], CD−32°7572, CPD−32°2953, FK5 1277, GC 14732, HIP 52407, HR 4194, SAO 201665, WDS J10427-3243A[14]
Database references
SIMBADdata

HD 92845 has a stellar classification of A0 V,[4] indicating that it is an ordinary A-type main-sequence star. However, stellar evolution models from Zorec and Royer reveal it to be a subgiant that has just left the main sequence.[3] It has 3.1 times the mass of the Sun[3] but has expanded to an enlarged radius of 5.31 R☉.[8] It radiates with a luminosity 206 times greater than the Sun[3] from its photosphere at an effective temperature of 9,376 K,[8] giving a white hue. At an age of 282 million years,[12] HD 92845 spins quickly with a projected rotational velocity of 81 km/s.[11]

There is an optical companion 17″ away along a position angle of 214° as of 1999.[16]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  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.
  3. Zorec, J.; Royer, F. (1 January 2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. ISSN 0004-6361. S2CID 55586789.
  4. Cucchiaro, A.; Macau-Hercot, D.; Jaschek, M.; Jaschek, C. (July 1978). "Spectral classification from the ultraviolet line features of S2/68 spectra. III. Early A-type stars". Astronomy and Astrophysics Supplement Series. 33: 15–26. Bibcode:1978A&AS...33...15C. ISSN 0365-0138.
  5. 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. 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. ISSN 1063-7737. S2CID 119231169.
  7. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  8. Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256.
  9. 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. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. ISSN 0004-6361.
  10. Gontcharov, G. A. (December 2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771–782. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. ISSN 0320-0108. S2CID 255201789.
  11. Royer, F.; Gerbaldi, M.; Faraggiana, R.; Gómez, A. E. (January 2002). "Rotational velocities of A-type stars". Astronomy & Astrophysics. 381 (1): 105–121. arXiv:astro-ph/0110490. Bibcode:2002A&A...381..105R. doi:10.1051/0004-6361:20011422. eISSN 1432-0746. ISSN 0004-6361.
  12. Gerbaldi, M.; Faraggiana, R.; Burnage, R.; Delmas, F.; Gómez, A. E.; Grenier, S. (June 1999). "Search for reference A0 dwarf stars: Masses and luminosities revisited withHipparcos parallaxes". Astronomy and Astrophysics Supplement Series. 137 (2): 273–292. Bibcode:1999A&AS..137..273G. doi:10.1051/aas:1999248. eISSN 1286-4846. ISSN 0365-0138.
  13. 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.
  14. "HR 4194". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved July 15, 2022.
  15. 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. eISSN 1365-2966. ISSN 0035-8711.
  16. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. ISSN 0004-6256.
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