HD 2454

HD 2454 is a probable binary star system in the zodiac constellation of Pisces. With an apparent visual magnitude of 6.04,[2] it is near the lower limit of visibility to the naked eye under good seeing conditions. An annual parallax shift of 27.36 mas as measured from Earth's orbit provides a distance estimate of 199 light years. It has a relatively high proper motion, traversing the celestial sphere at a rate of 0.208 arcseconds per year,[11] and is moving closer to the Sun with a heliocentric radial velocity of −10 km/s.[5]

HD 2454
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pisces
Right ascension  00h 28m 20.05173s[1]
Declination +10° 11′ 23.4501″[1]
Apparent magnitude (V) 6.04[2]
Characteristics
Spectral type F5 V Sr[3]
B−V color index 0.447 ± 0.005[4]
Astrometry
Radial velocity (Rv)−9.9±0.2[5] km/s
Proper motion (μ) RA: +33.04[1] mas/yr
Dec.: −203.30[1] mas/yr
Parallax (π)27.36 ± 0.32[1] mas
Distance119 ± 1 ly
(36.5 ± 0.4 pc)
Absolute magnitude (MV)3.24±0.03[2]
Details
Mass1.23[6] M☉
Radius1.6±0.1[7] R☉
Luminosity4.59[4] L☉
Surface gravity (log g)0.14±4.22[6] cgs
Temperature6,508±221[6] K
Metallicity [Fe/H]−0.32[2] dex
Rotation3 days[8]
Age1.865[6] Myr
Other designations
88[9] G. Piscium, BD+09° 47, FK5 2028, HD 2454, HIP 2235, HR 107, SAO 109224[10]
Database references
SIMBADdata

The visible component of this system is an F-type main-sequence star with a stellar classification of F5 V Sr,[3] showing an abnormally strong line of singly-ionized strontium (Sr II) at a wavelength of 4077 Å.[12] It has an estimated 1.23[6] times the mass of the Sun and 1.6[7] times the Sun's radius. The star is about 1.9[6] billion years old with a rotation period of around three days.[8] It is radiating 4.6[4] times the Sun's luminosity from its photosphere at an effective temperature of around 6,508 K.[6]

HD 2454 was the first star to be identified as a Barium dwarf, by Tomkin et al. (1989),[13] and is the brightest such object.[2] It displays a mild overabundance of the element barium, which is hypothesized to have been accreted when an unresolved white dwarf companion was passing through the asymptotic giant branch (RGB) stage.[13]

The visible component displays significant overabundances of three s-process peak elements that are generated during the RGB phase, as well as a mild overabundance of carbon.[14] In contrast, it shows severe depletion of lithium and beryllium, as well as a notable underabundance of boron. The surface abundances of these lighter elements may have been altered during the mass transfer process, having been previously consumed in the core region of the companion.[15]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. Gray, R. O.; et al. (May 2011), "First Direct Evidence That Barium Dwarfs Have White Dwarf Companions", The Astronomical Journal, 141 (5): 8, Bibcode:2011AJ....141..160G, doi:10.1088/0004-6256/141/5/160, 160.
  3. Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2006), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample", The Astronomical Journal, 132: 161, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
  4. 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.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  6. David, Trevor J.; Hillenbrand, Lynne A. (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.
  7. Allen, D. M.; Barbuy, B. (August 2006), "Analysis of 26 barium stars. I. Abundances", Astronomy and Astrophysics, 454 (3): 895−915, arXiv:astro-ph/0604036, Bibcode:2006A&A...454..895A, doi:10.1051/0004-6361:20064912.
  8. Baliunas, S.; et al. (1996), "Magnetic Field and Rotation in Lower Main-Sequence Stars: an Empirical Time-dependent Magnetic Bode's Relation?", Astrophysical Journal Letters, 457 (2): L99, Bibcode:1996ApJ...457L..99B, doi:10.1086/309891.
  9. Gould, Benjamin Apthorp (1879), Uranometria Argentina catalog of bright southern stars, Bibcode:1879RNAO....1.....G, retrieved 2018-02-26
  10. "HD 2454". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-22.
  11. Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal, 129 (3): 1483–1522, arXiv:astro-ph/0412070, Bibcode:2005AJ....129.1483L, doi:10.1086/427854.
  12. Gray, C. Richard O.; Corbally, J. (2009), Stellar Spectral Classification, Princeton University Press, pp. 247–248, ISBN 0691125112.
  13. Tomkin, J.; et al. (July 1989), "HR 107 - an F-type mild barium dwarf star", Astronomy and Astrophysics, 219: L15−L18, Bibcode:1989A&A...219L..15T.
  14. Roederer, Ian U. (September 2012), "Germanium, Arsenic, and Selenium Abundances in Metal-poor Stars", The Astrophysical Journal, 756 (1): 11, arXiv:1207.0518, Bibcode:2012ApJ...756...36R, doi:10.1088/0004-637X/756/1/36, 36.
  15. Boesgaard, Ann Merchant; et al. (March 2005), "Boron Depletion in F and G Dwarf Stars and the Beryllium-Boron Correlation", The Astrophysical Journal, 621 (2): 991−998, arXiv:astro-ph/0411246, Bibcode:2005ApJ...621..991B, doi:10.1086/427687.
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