Astronomy:Chi Ursae Majoris
  | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 11h 46m 3.01407s[1] |
| Declination | +47° 46′ 45.8626″[1] |
| Apparent magnitude (V) | 3.72[2] |
| Characteristics | |
| Evolutionary stage | Horizontal branch[3] |
| Spectral type | K0.5 IIIb[4] |
| U−B color index | +1.16[2] |
| B−V color index | +1.18[2] |
| Astrometry | |
| Radial velocity (Rv) | −9.02±0.20[2] km/s |
| Proper motion (μ) | RA: −138.29[1] mas/yr Dec.: 28.57[1] mas/yr |
| Parallax (π) | 17.76 ± 0.16[1] mas |
| Distance | 184 ± 2 ly (56.3 ± 0.5 pc) |
| Absolute magnitude (MV) | 0.10±0.02[5] |
| Details[2] | |
| Mass | 1.49[6] M☉ |
| Radius | 20.8±0.8[7] R☉ |
| Luminosity | 158 L☉ |
| Surface gravity (log g) | 2.2 cgs |
| Temperature | 4,416±9 K |
| Metallicity [Fe/H] | −0.44 dex |
| Rotational velocity (v sin i) | 2.3 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Chi Ursae Majoris or χ Ursae Majoris, formally named Taiyangshou /ˌtaɪˌjæŋˈʃoʊ/,[10] is a single[11] star in the northern circumpolar constellation of Ursa Major. The star has an orange hue and is visible to the naked eye at night with an apparent visual magnitude of 3.72.[2] It is located at a distance of approximately 184 light-years from the Sun based on parallax, but is drifting closer with a radial velocity of −9 km/s.[2]
Nomenclature
χ Ursae Majoris (Latinised to Chi Ursae Majoris) is the star's Bayer designation.
It bore the traditional name Tai Yang Show, "the Sun Governor", from Chinese astronomy.[12] The name was possibly derived from the word 太陽守, Pinyin: Tàiyángshǒu, meaning Guard of the Sun, because this star is marking itself and standing alone in the Guard of the Sun asterism, Purple Forbidden enclosure (see : Chinese constellations). It also bore traditional names of Arabic origin: Alkafzah, Alkaphrah, and El Koprah.[8]
In 2016, the IAU organized a Working Group on Star Names (WGSN)[13] to catalog and standardize proper names for stars. The WGSN approved the name Taiyangshou for this star on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.[10]
Properties
Chi Ursae Majoris is an evolved, orange hued K-type giant with a stellar classification of K0.5 IIIb.[4] It is a red clump giant,[3] which means it is on the horizontal branch and is generating energy through helium fusion at its core. This star has expanded to 20.8±0.8[7] times the radius of the Sun with 1.49 times the Sun's mass.[6] It is radiating 158 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,416 K.[2]
The spiral galaxy in Ursa Major, NGC 3877 (= H I.201), type Sc, is best found from Chi Ursae Majoris, which is almost exactly 15 arcminutes north of the galaxy.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society 172 (3): 667–679, doi:10.1093/mnras/172.3.667, Bibcode: 1975MNRAS.172..667J.
- ↑ 3.0 3.1 Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal 539 (2): 732–741, doi:10.1086/309278, Bibcode: 2000ApJ...539..732A.
- ↑ 4.0 4.1 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series 71: 245, doi:10.1086/191373, Bibcode: 1989ApJS...71..245K.
- ↑ Park, Sunkyung et al. (2013), "Wilson-Bappu Effect: Extended to Surface Gravity", The Astronomical Journal 146 (4): 73, doi:10.1088/0004-6256/146/4/73, Bibcode: 2013AJ....146...73P.
- ↑ 6.0 6.1 Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal 150 (3): 88, doi:10.1088/0004-6256/150/3/88, Bibcode: 2015AJ....150...88L.
- ↑ 7.0 7.1 Nordgren, Tyler E. et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer", The Astronomical Journal 118 (6): 3032–3038, doi:10.1086/301114, Bibcode: 1999AJ....118.3032N, http://digitalcommons.wcupa.edu/cgi/viewcontent.cgi?article=1008&context=phys_facpub.
- ↑ 8.0 8.1 8.2 Bakich, Michael E. (1995), The Cambridge Guide to the Constellations, Cambridge University Press, pp. 112, 116, ISBN 0521449219, https://books.google.com/books?id=tLMXiFhTnRYC&pg=PA112
- ↑ "chi UMa". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=chi+UMa.
- ↑ 10.0 10.1 "Naming Stars". IAU.org. https://www.iau.org/public/themes/naming_stars/. Retrieved 16 December 2017.
- ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Ursa Major
- ↑ "IAU Working Group on Star Names (WGSN)". https://www.iau.org/science/scientific_bodies/working_groups/280/. Retrieved 22 May 2016.
External links
- Chi Ursae Majoris on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
 |  |
