HD 210056

HD 210056, also known as HR 8432, is a solitary orange hued star located in the southern circumpolar constellation Octans. Eggen (1993) listed it as a member of the old disk population.[12]

HD 210056
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Octans
Right ascension 22h 11m 54.98416s[1]
Declination −76° 06′ 57.6788″[1]
Apparent magnitude (V) 6.13±0.01[2]
Characteristics
Spectral type K0 III[3]
U−B color index +0.82[4]
B−V color index +1.00[4]
Astrometry
Radial velocity (Rv)24±1[5] km/s
Proper motion (μ) RA: −59.351 mas/yr[1]
Dec.: −40.005 mas/yr[1]
Parallax (π)11.1656 ± 0.0205 mas
Distance292.1 ± 0.5 ly
(89.6 ± 0.2 pc)
Absolute magnitude (MV)+1.41[6]
Details[7]
Mass1.59±0.07 M☉
Radius7.72±0.13 R☉
Luminosity29.7±0.5 L☉
Surface gravity (log g)2.86±0.10 cgs
Temperature4,849±37 K
Metallicity [Fe/H]−0.08±0.03 dex
Rotational velocity (v sin i)<1.5[8] km/s
Age2.10±0.22[9] Gyr
Other designations
68 G. Octantis[10], CD−76°1120, CPD−76°1549, GC 31004, HD 210056, HIP 109584, HR 8432, SAO 258006[11]
Database references
SIMBADdata

The object has an apparent magnitude of 6.13,[2] making it barely visible to the naked eye. Based on parallax measurements from the Gaia satellite, the object is estimated to be 292 light years distant.[1] It appears to be receding with a heliocentric radial velocity of 24 km/s.[5] At its current distance, HD 210056's brightness is diminished by 0.2 magnitudes due to interstellar dust. It has an absolute magnitude of +1.41.[13]

This is an evolved giant star with a stellar classification of K0 III. It has 1.59 times the mass of the Sun but has expanded to 7.72 times its girth.[7] It radiates 29.7 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,849 K.[7] Based on asteroseismologic measurements, HD 210056 is estimated to be 2 billion years old.[9] The star has about 90% of the Sun's metallicity — what astronomers define a star's abundance of chemical elements heavier than helium.[7] It currently spins slowly with a projected rotational velocity lower than 1.5 km/s.[9]

References
  1. 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. 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. Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations −90° to −53°. Bibcode:1975mcts.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. Bibcode:1966CoLPL...4...99J.
  5. 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.
  6. 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.
  7. Ottoni, G.; Udry, S.; Ségransan, D.; Buldgen, G.; Lovis, C.; Eggenberger, P.; Pezzotti, C.; Adibekyan, V.; Marmier, M.; Mayor, M.; Santos, N. C.; Sousa, S. G.; Lagarde, N.; Charbonnel, C. (January 2022). "CORALIE radial-velocity search for companions around evolved stars (CASCADES): I. Sample definition and first results: Three new planets orbiting giant stars". Astronomy & Astrophysics. 657: A87. arXiv:2201.01528. Bibcode:2022A&A...657A..87O. doi:10.1051/0004-6361/202040078. eISSN 1432-0746. ISSN 0004-6361.
  8. 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". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. eISSN 1432-0746. ISSN 0004-6361.
  9. Aguirre, Víctor Silva; et al. (29 January 2020). "Detection and Characterization of Oscillating Red Giants: First Results from the TESS Satellite". The Astrophysical Journal. 889 (2): L34. arXiv:1912.07604. Bibcode:2020ApJ...889L..34S. doi:10.3847/2041-8213/ab6443. eISSN 2041-8213.
  10. 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.
  11. "HD 210056". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 21, 2022.
  12. Eggen, O. J. (July 1993). "Evolved GK stars near the sun. I - The old disk population". The Astronomical Journal. 106: 80. Bibcode:1993AJ....106...80E. doi:10.1086/116622.
  13. 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.
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