Mu Pegasi or μ Pegasi, formally named Sadalbari (/ˌsædəlˈbɛəri/),[10] is a star in the northern constellation of Pegasus. The apparent visual magnitude of this star is 3.5,[2] which is bright enough to be seen with the naked eye even on a moonlit night. Based upon parallax measurements taken by the Gaia spacecraft, it is approximately 113 light-years (35 parsecs) from the Sun.[1]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 22h 50m 00.19307s[1] |
| Declination | +24° 36′ 05.6926″[1] |
| Apparent magnitude (V) | 3.514[2] |
| Characteristics | |
| Evolutionary stage | Yellow giant |
| Spectral type | G8 III[3] |
| U−B color index | +0.674[2] |
| B−V color index | +0.932[2] |
| Astrometry | |
| Radial velocity (Rv) | +13.54 ± 0.20[4] km/s |
| Proper motion (μ) | RA: +145.240 mas/yr[1] Dec.: −42.396 mas/yr[1] |
| Parallax (π) | 28.934 ± 0.189 mas[1] |
| Distance | 112.7 ± 0.7 ly (34.6 ± 0.2 pc) |
| Absolute magnitude (MV) | +0.432[5] |
| Details | |
| Mass | 2.59±0.05[6] M☉ |
| Radius | 9.32±0.47[7] R☉ |
| Luminosity | 46.9±0.6[8] L☉ |
| Surface gravity (log g) | 2.85±0.03[8] cgs |
| Temperature | 4,961±40[8] K |
| Metallicity [Fe/H] | −0.03±0.02[8] dex |
| Rotational velocity (v sin i) | 0.95±0.45[6] km/s |
| Age | 520±30[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Nomenclature
editμ Pegasi (Latinised to Mu Pegasi) is the star's Bayer designation.
It bore the traditional name Sadalbari, which derives from Arabic: سعد بارع saʿd al-bāriʿ, the “auspicious star of the splendid one.”[11] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[12] to catalogue and standardize proper names for stars. The WGSN approved the name Sadalbari for this star on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[10]
In Chinese, 離宮 (Lì Gōng), meaning Resting Palace, refers to an asterism consisting of Mu Pegasi, Lambda Pegasi, Omicron Pegasi, Eta Pegasi, Tau Pegasi and Nu Pegasi.[13] Consequently, the Chinese name for Mu Pegasi itself is 離宮二 (Lì Gōng èr, "the Second Star of Resting Palace").[14]
Properties
editThe spectrum of this star matches a stellar classification of G8 III.[3] The luminosity class of 'III' means that it has exhausted the hydrogen fuel at its core and evolved into a giant star. It is 520 million years old and 2.6 times more massive than the Sun,[6] but has expanded to nine times the Sun's radius.[7] The effective temperature of the outer atmosphere is about 4,961 K,[8] which is cooler than the Sun and gives it the yellow hue of a G-type star.[15][16] The abundance of elements other than hydrogen and helium, what astronomers term the metallicity, is a bit smaller than the abundance in the Sun.[8]
References
edit- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c d 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, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667
- ^ a b Frasca, A.; et al. (December 2009), "REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters", Astronomy and Astrophysics, 508 (3): 1313–1330, arXiv:0911.0760, Bibcode:2009A&A...508.1313F, doi:10.1051/0004-6361/200913327, S2CID 118361131
- ^ Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304
- ^ Mishenina, T. V.; et al. (September 2006), "Elemental abundances in the atmosphere of clump giants", Astronomy and Astrophysics, 456 (3): 1109–1120, arXiv:astro-ph/0605615, Bibcode:2006A&A...456.1109M, doi:10.1051/0004-6361:20065141, S2CID 18764566
- ^ a b c d Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; Artur de la Villarmois, E.; Chavero, C.; Gómez, M.; Mauas, P. J. D. (2015-02-01). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy and Astrophysics. 574: A50. arXiv:1410.6422. Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474. ISSN 0004-6361. S2CID 53666931. Mu Pegasi's database entry at VizieR.
- ^ a b Baines, Ellyn K.; Thomas Armstrong, J.; Clark, James H.; Gorney, Jim; Hutter, Donald J.; Jorgensen, Anders M.; Kyte, Casey; Mozurkewich, David; Nisley, Ishara; Sanborn, Jason; Schmitt, Henrique R.; Van Belle, Gerard T. (2021), "Angular Diameters and Fundamental Parameters of Forty-four Stars from the Navy Precision Optical Interferometer", The Astronomical Journal, 162 (5): 198, arXiv:2211.09030, Bibcode:2021AJ....162..198B, doi:10.3847/1538-3881/ac2431
- ^ a b c d e f Soubiran, C.; Creevey, O. L.; Lagarde, N.; Brouillet, N.; Jofré, P.; Casamiquela, L.; Heiter, U.; Aguilera-Gómez, C.; Vitali, S.; Worley, C.; de Brito Silva, D. (2024-02-01), "Gaia FGK benchmark stars: Fundamental Teff and log g of the third version", Astronomy and Astrophysics, 682: A145, Bibcode:2024A&A...682A.145S, doi:10.1051/0004-6361/202347136, ISSN 0004-6361 Mu Pegasi's database entry at VizieR.
- ^ "48 Peg -- High proper-motion Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-28
- ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
- ^ Allen, Richard Hinckley (1963) [1899]. Star Names: Their Lore and Meaning (rep. ed.). New York, NY: Dover Publications Inc. pp. 328–29. ISBN 0-486-21079-0.
- ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
- ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2008-10-25 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 18, 2012, retrieved 2012-01-16
- ^ Kaler, James B., "SADALBARI (Lambda and Mu Pegasi)", Stars, University of Illinois, retrieved 2012-01-28