Nu Pegasi

ν Pegasi, Latinized as Nu Pegasi is a single^[12] star in the northern constellation of Pegasus. It is an orange-hued star that is faintly visible to the naked eye with an apparent visual magnitude of 4.84.^[2] The star is located approximately 261 light years away based on parallax,^[7] but is drifting closer with a radial velocity of −19 km/s.^[6]

Nu Pegasi

Location of ν Pegasi (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Pegasus
Right ascension	22h 05m 40.75170s[1]
Declination	5° 03′ 30.7201″[1]
Apparent magnitude (V)	4.84[2]
Characteristics
Evolutionary stage	red giant branch[3]
Spectral type	K4III[4]
U−B color index	+1.80[2]
B−V color index	+1.44[2]
Variable type	suspected[5]
Astrometry
Radial velocity (Rv)	−18.90[6] km/s
Proper motion (μ)	RA: +101.759[7] mas/yr Dec.: +100.923[7] mas/yr
Parallax (π)	12.4810 ± 0.3322 mas[7]
Distance	261 ± 7 ly (80 ± 2 pc)
Absolute magnitude (MV)	0.26[8]
Details[9]
Mass	1.13 M☉
Radius	24.57 R☉
Luminosity	149 L☉
Surface gravity (log g)	1.72 cgs
Temperature	4,073 K
Metallicity [Fe/H]	+0.02 dex
Rotational velocity (v sin i)	2.3[10] km/s
Age	8.1+2.3 −0.4[3] Gyr
Other designations
ν Peg, 22 Pegasi, NSV 14020, BD+04°4800, GC 30894, HD 209747, HIP 109068, HR 8413, SAO 127285[11]
Database references
SIMBAD	data

This is an aging giant star, most likely (94% chance) on the red giant branch,^[3] with a stellar classification of K4III.^[4] It is a suspected variable, with a magnitude range observed from 4.83 to 4.86.^[5] With the supply of hydrogen at its core exhausted, the star has cooled and expanded to 24.6 times the Sun's radius. It is 13% more massive than the Sun and is radiating 149 times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,073 K.^[9]

References

1. 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. Vizier catalog entry
2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
3. Stock, Stephan; et al. (August 2018). "Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search". Astronomy & Astrophysics. 616: 15. arXiv:1805.04094. Bibcode:2018A&A...616A..33S. doi:10.1051/0004-6361/201833111. S2CID 119361866. A33.
4. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
5. Samus, N. N.; Durlevich, O. V.; et al. (2009). "General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
6. Famaey, B.; et al. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data". Astronomy & Astrophysics. 430: 165–186. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. S2CID 17804304.
7. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
8. 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. Vizier catalog entry
9. Reffert, Sabine; et al. (2015). "Precise radial velocities of giant stars". Astronomy & Astrophysics. 574: A116. arXiv:1412.4634. Bibcode:2015A&A...574A.116R. doi:10.1051/0004-6361/201322360. hdl:10722/215277. S2CID 59334290. Vizier catalog entry
10. De Medeiros, J. R.; Mayor, M. (1999). "A catalog of rotational and radial velocities for evolved stars". Astronomy and Astrophysics Supplement Series. 139 (3): 433. arXiv:astro-ph/0608248. Bibcode:1999A&AS..139..433D. doi:10.1051/aas:1999401. Vizier catalog entry
11. "nu. Peg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-01.
12. 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.