Omega Ursae Majoris
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 10h 53m 58.74035s[1] |
| Declination | +43° 11′ 23.8483″[1] |
| Apparent magnitude (V) | 4.61[2] |
| Characteristics | |
| Spectral type | A1VsSi:[3] or A0 IV−V[4] |
| U−B color index | −0.11[2] |
| B−V color index | −0.04[2] |
| Astrometry | |
| Radial velocity (Rv) | −18.70±0.80[5] km/s |
| Proper motion (μ) | RA: +42.97[1] mas/yr Dec.: −23.62[1] mas/yr |
| Parallax (π) | 13.24 ± 0.50 mas[1] |
| Distance | 246 ± 9 ly (76 ± 3 pc) |
| Absolute magnitude (MV) | +0.86[6] |
| Orbit[7] | |
| Period (P) | 15.8307 d |
| Eccentricity (e) | 0.31 |
| Periastron epoch (T) | 2435185.246 JD |
| Argument of periastron (ω) (secondary) | 27.3° |
| Semi-amplitude (K1) (primary) | 22.2 km/s |
| Details | |
| Radius | 2.5[8] R☉ |
| Luminosity | 76[9] L☉ |
| Surface gravity (log g) | 3.88[4] cgs |
| Temperature | 9,647[9] K |
| Rotational velocity (v sin i) | 47[10] km/s |
| Age | 325[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Omega Ursae Majoris (Omega UMa, ω Ursae Majoris, ω UMa) is the Bayer designation for a binary star system in the northern circumpolar constellation of Ursa Major. It is visible to the naked eye with an apparent visual magnitude of 4.61.[2] Based upon an annual parallax shift of 13.24 mas,[1] it is roughly 246 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.11 due to interstellar dust.[6]
This is a single-lined spectroscopic binary star system with an orbital period of 15.8 days and an eccentricity of 0.31.[7] The primary member, component A, is an A-type main sequence star with a stellar classification of A1VsSi:.[3] The stellar spectrum has the appearance of a hot Am star, showing overabundances of many iron-peak and heavier elements, but an underabundance of helium.[12] In particular, it has an abnormal abundance of silicon.[13]
Naming
In Chinese, 天牢 (Tiān Láo), meaning Celestial Prison, refers to an asterism consisting of ω Ursae Majoris, 57 Ursae Majoris, 47 Ursae Majoris, 58 Ursae Majoris, 49 Ursae Majoris and 56 Ursae Majoris. Consequently, the Chinese name for ω Ursae Majoris itself is 天牢一 (Tiān Láo yī, Template:Lang-en.).[14]
References
- ^ 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.
- ^ 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 Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
- ^ a b Adelman, S. J. (2005), "The physical properties of normal a stars", Proceedings of the International Astronomical Union, 2004: 1–11, Bibcode:2004IAUS..224....1A, doi:10.1017/S1743921304004314.
- ^ 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.
- ^ a b c Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.
- ^ a b Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics, 424 (2): 727, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213.
- ^ Pasinetti-Fracassini, L. E.; et al. (February 2001), "Catalog 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.
- ^ a b 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.
{{citation}}: CS1 maint: unflagged free DOI (link) - ^ 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.
- ^ "* ome UMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-02-22.
{{cite web}}: CS1 maint: postscript (link) - ^ Caliskan, Hulya; Adelman, Saul J. (June 1997), "Elemental abundance analyses with DAO spectrograms - XVII. The superficially normal early A stars 2 Lyncis, omicron Ursa Majoris and phiAquilae", Monthly Notices of the Royal Astronomical Society, 288 (2): 501–511, Bibcode:1997MNRAS.288..501C, doi:10.1093/mnras/288.2.501.
- ^ Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars" (PDF), Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
- ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 21 日
