HD 21819

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HD 21819
Location of HD 21819 on the map (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Camelopardalis
Right ascension 03h 33m 39.06000s[1]
Declination +54° 58′ 29.4970″[1]
Apparent magnitude (V) 5.97±0.01[2]
Characteristics
Evolutionary stage main sequence star[3]
Spectral type A3 V[4] or A2 Vp[5]
B−V color index +0.11[6]
Astrometry
Radial velocity (Rv)−6.5±1.5[7] km/s
Proper motion (μ) RA: −41.053 mas/yr[1]
Dec.: −0.357 mas/yr[1]
Parallax (π)13.1723 ± 0.0317 mas[1]
Distance247.6 ± 0.6 ly
(75.9 ± 0.2 pc)
Absolute magnitude (MV)+1.62[8]
Details
Mass2.00+0.19
−0.15[9] M☉
Radius2.06±0.10[10] R☉
Luminosity30.6+2.2
−2.0[3] L☉
Surface gravity (log g)4.08[11] cgs
Temperature9,000[12] K
Metallicity [Fe/H]−0.17[11] dex
Rotational velocity (v sin i)160±8[5] km/s
Age737±102[9] Myr
Other designations
AG+54°370, BD+54°693, GC 4229, HD 21819, HIP 16599, HR 1073, SAO 24099, TIC 316848255[13]
Database references
SIMBADdata

HD 21819, also designated as HR 1073, is a solitary star[14] located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.97,[2] making faintly visible to the naked eye under ideal conditions. The object is located relatively close at a distance of 248 light-years based on Gaia DR3 parallax measurements[1] and it is drifting closer with a heliocentric radial velocity of −6.5 km/s.[7] At its current distance, HD 21819's brightness is diminished by an interstellar extinction of 0.17 magnitudes[15] and it has an absolute magnitude of +1.62.[8]

HD 21819 has a stellar classification of A3 V,[4] indicating that it is an ordinary A-type main-sequence star that is generating energy via hydrogen fusion at its core. Abt & Morell (1995) gave a slightly hotter star of A2 Vp,[5] indicating that it is instead an Ap star with weak magnesium lines. It has twice the mass of the Sun[9] and 2.06 times the radius of the Sun.[10] It radiates 30.6 times the luminosity of the Sun[3] from its photosphere at an effective temperature of 9,000 K,[12] giving it a white hue when viewed in the night sky. HD 21819 is metal deficient with an iron abundance of [Fe/H] = −0.17 or 67.6% of the Sun's[11] and it is estimated to be 737 million years old,[9] having completed 55.7% of its main sequence lifetime.[3] Like most hot stars it spins rapidly, having a projected rotational velocity of 160 km/s.[5]

References[edit]

  1. ^ a b c d e 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. ^ a b 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. ^ a b c d 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. ^ a b Cowley, A.; Cowley, C.; Jaschek, M.; Jaschek, C. (April 1969). "A study of the bright stars. I. A catalogue of spectral classifications". The Astronomical Journal. 74: 375. Bibcode:1969AJ.....74..375C. doi:10.1086/110819. ISSN 0004-6256. S2CID 121555804.
  5. ^ a b c d Abt, Helmut A.; Morrell, Nidia I. (July 1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182. ISSN 0067-0049. S2CID 120495962.
  6. ^ Häggkvist, L.; Oja, T. (1969). "Photoelectric BV photometry of 368 northern stars". Arkiv for Astronomi. 5: 125–135. Bibcode:1969ArA.....5..125H. ISSN 0004-2048.
  7. ^ a b 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. ^ a b 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. ^ a b c d 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. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. eISSN 1538-4357. S2CID 33401607.
  10. ^ a b 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. S2CID 6077801.
  11. ^ a b c 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. eISSN 1432-0746. ISSN 0004-6361. S2CID 131780028.
  12. ^ a b 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.
  13. ^ "HD 21819". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved December 24, 2023.
  14. ^ De Rosa, R. J.; et al. (26 November 2013). "The VAST Survey – III. The multiplicity of A-type stars within 75 pc". Monthly Notices of the Royal Astronomical Society. 437 (2): 1216–1240. arXiv:1311.7141. Bibcode:2014MNRAS.437.1216D. doi:10.1093/mnras/stt1932. eISSN 1365-2966. ISSN 0035-8711. S2CID 88503488.
  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. arXiv:1709.01160. Bibcode:2017MNRAS.472.3805G. doi:10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711. S2CID 118879856.
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