Delta Doradus
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Dorado |
Right ascension | 05h 44m 46.37811s[1] |
Declination | −65° 44′ 07.9011″[1] |
Apparent magnitude (V) | +4.34[2] |
Characteristics | |
Spectral type | A7 V[3] |
U−B color index | +0.11[2] |
B−V color index | +0.22[2] |
Astrometry | |
Radial velocity (Rv) | −8.3±0.8[4] km/s |
Proper motion ( | RA: −28.91[1] mas/yr Dec.: +5.17[1] mas/yr |
Parallax ( | 21.80 ± 0.14 mas[1] |
Distance | 149.6 ± 1.0 ly (45.9 ± 0.3 pc) |
Absolute magnitude (MV) | +1.03[5] |
Details | |
Mass | 1.85[6] M☉ |
Radius | 2.1[7] R☉ |
Luminosity | 29[8] L☉ |
Surface gravity (log g) | 3.89[6] cgs |
Temperature | 7,828±266[6] K |
Metallicity [Fe/H] | −0.40[9] dex |
Rotational velocity (v sin i) | 172[3] km/s |
Age | 940[6] Myr |
Other designations | |
Database references | |
SIMBAD | data |
This is an A-type main sequence star with a stellar classification of A7 V.[3] The star is spinning rapidly with a projected rotational velocity of 172 km/s.[3] This is giving the star an oblate shape with an equatorial bulge that is 12% larger than the polar radius.[11] Although A-type stars are not expected to harbor a magnetic dynamo needed to power X-ray emission, an X-ray flux of 3.6×1027 erg/s has been detected at these coordinates. This may indicate that the star has an unseen companion.[12]
Currently this star is the Moon's south pole star, which occurs once every 18.6 years.[13] The pole star status changes periodically, because of the precession of the Moon's rotational axis. When
References
[edit]- ^ a b c d e 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, S2CID 18759600.
- ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
- ^ a b c d Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298.
- ^ 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.
- ^ 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 c d 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.
- ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (3rd ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
- ^ McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
- ^ a b Saffe, C.; Gómez, M.; Pintado, O.; González, E. (October 2008), "Spectroscopic metallicities of Vega-like stars", Astronomy and Astrophysics, 490 (1): 297–305, arXiv:0805.3936, Bibcode:2008A&A...490..297S, doi:10.1051/0004-6361:200810260, S2CID 15059920.
- ^ "del Dor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-04-17.
{{cite web}}
: CS1 maint: postscript (link) - ^ van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.
- ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677–684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.
- ^ Patrick Moore (1983), The Guinness Book of Astronomy Facts & Feats, p. 29,
In 1968 the north pole star of the Moon was Omega Draconis; by 1977 it was 36 Draconis. The south pole star is Delta Doradus.