26 Ursae Majoris is a single[9] star in the northern circumpolar constellation of Ursa Major, located 262 light years away from the Sun.[1] It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.47.[2] The object is moving further from the Earth with a heliocentric radial velocity of +22 km/s.[5]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 09h 34m 49.43259s[1] |
| Declination | +52° 03′ 05.3165″[1] |
| Apparent magnitude (V) | 4.47[2] |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | A0 Vn[3] |
| U−B color index | +0.00[4] |
| B−V color index | +0.027±0.013[2] |
| Astrometry | |
| Radial velocity (Rv) | +22.2±1.1[5] km/s |
| Proper motion (μ) | RA: −65.74[1] mas/yr Dec.: −37.32[1] mas/yr |
| Parallax (π) | 12.44 ± 0.19 mas[1] |
| Distance | 262 ± 4 ly (80 ± 1 pc) |
| Absolute magnitude (MV) | −0.06[2] |
| Details | |
| Mass | 2.16[6] M☉ |
| Radius | 2.2[7] R☉ |
| Luminosity | 99.2[2] L☉ |
| Surface gravity (log g) | 3.94[6] cgs |
| Temperature | 9,757±332[6] K |
| Rotational velocity (v sin i) | 165[3] km/s |
| Age | 147[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is an A-type main-sequence star with a stellar classification of A0 Vn,[3] where the 'n' indicates "nebulous" lines in the spectrum due to rapid rotation. It has a high rate of spin with a projected rotational velocity of 165 km/s,[3] which is giving it an oblate shape with an equatorial bulge that is 8% larger than the polar radius.[10] The star is 147[6] million years old with just over double[6] the mass of the Sun and twice[7] the Sun's radius. It is radiating 99[2] times the Sun's luminosity from its photosphere at an effective temperature of 9,757 K.[6]
References
edit- ^ a b c d e f 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 e f 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 Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.
- ^ Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- ^ a b Gontcharov, G. A. (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. S2CID 119231169.
- ^ 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 Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (Third ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
- ^ "26 UMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-19.
- ^ Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
- ^ 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