HD 2454
Probable binary star system in the constellation Pisces
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 26.3 mas as measured from Earth's orbit provides a distance estimate of 124 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]
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
^ a b c d 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 .
^ a b c d e 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.
^ a b 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 (1): 161–170, arXiv :astro-ph/0603770 , Bibcode :2006AJ....132..161G , doi :10.1086/504637 , S2CID 119476992 .
^ a b c 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 .
^ a b 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 , S2CID 59451347 , A61.
^ a b c d e f g 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 , S2CID 33401607 .
^ a b 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 , S2CID 6378168 .
^ a b 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 .
^ Gould, Benjamin Apthorp (1879), "Uranometria Argentina catalog of bright southern stars" , Resultados del Observatorio Nacional Argentino , 1 , Bibcode :1879RNAO....1.....G , retrieved 2018-02-26 .
^ "HD 2454" . SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2018-02-22 .
^ 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 , S2CID 2603568 .
^ Gray, C. Richard O.; Corbally, J. (2009), Stellar Spectral Classification , Princeton University Press , pp. 247–248, ISBN 978-0691125114 .
^ a b 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 .
^ 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 , S2CID 118407008 , 36.
^ 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 , S2CID 8994810 .