1 Pegasi

Star in the constellation Pegasus

1 Pegasi
Observation data Epoch J2000 Equinox J2000
Location of 1 Pegasi (circled)
Constellation	Pegasus
Right ascension	21^h 22^m 05.199^s^[1]
Declination	19° 48′ 16.24″^[1]
Apparent magnitude (V)	4.09^[2]
Characteristics
Spectral type	K1III^[3]
U−B color index	+1.05^[2]
B−V color index	+1.11^[2]
Astrometry

Radial velocity (R_v)	−10.80^[4] km/s
Proper motion (μ)	RA: +105.35^[1] mas/yr Dec.: +63.51^[1] mas/yr
Parallax (π)	20.93 ± 0.17 mas^[1]
Distance	156 ± 1 ly (47.8 ± 0.4 pc)
Absolute magnitude (M_V)	0.68^[5]

Details
1 Peg A
Mass	1.57^[6] `M`_☉
Radius	12^[6] `R`_☉
Luminosity	71.78^[5] `L`_☉
Surface gravity (log g)	2.59^[7] cgs
Temperature	4,600^[8] K
Metallicity [Fe/H]	+0.01^[7] dex
Rotational velocity (v sin i)	1.2^[9] km/s

Other designations
1 Peg, BD+19°4691, FK5 804, GC 29914, HD 203504, HIP 105502, HR 8173, SAO 107073, CCDM J21221+1949A, WDS J21221+1948A^[10]
Database references
SIMBAD	data

1 Pegasi (1 Peg) is a triple star^[11] system in the constellation Pegasus, located approximately 156 light years away from the Sun based on parallax.^[1] It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.09.^[2] The system is moving closer to the Earth with a heliocentric radial velocity of −11 km/s.^[4]

The primary component is a giant with a stellar classification of K1III,^[3] a star that has exhausted the hydrogen supply at its core and evolved away from the main sequence. It has 1.57^[6] times the mass of the Sun and has expanded to 12^[6] times the Sun's radius. The star is radiating 72^[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,600 K.^[8]

There are several companions in addition to the primary. The brightest, component B, is a magnitude 9.3, K-type main-sequence star with a class of K0 V orbiting at an angular separation of 36.6" from the primary; it is itself a single-lined spectroscopic binary with an orbital period of 3.042 ± 0.011 years and eccentricity of 0.290±0.022.^[12] Visual companions C, with magnitude 12.9 and separation 64.7", and D, with magnitude 9.6 and separation 5.3", have been reported.^[13]

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. S2CID 18759600. Vizier catalog entry
^ ^a ^b ^c ^d 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.
^ ^a ^b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
^ ^a ^b Bakos, G. A. (1974). "Radial velocity measurements of visual binaries. 1". The Astronomical Journal. 79: 866. Bibcode:1974AJ.....79..866B. doi:10.1086/111622.
^ ^a ^b ^c 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
^ ^a ^b ^c ^d Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
^ ^a ^b Wu, Yue; Singh, H. P.; Prugniel, P.; Gupta, R.; Koleva, M. (2010). "Coudé-feed stellar spectral library – atmospheric parameters". Astronomy & Astrophysics. 525: A71. arXiv:1009.1491. Bibcode:2011A&A...525A..71W. doi:10.1051/0004-6361/201015014. S2CID 53480665.
^ ^a ^b Gontcharov, G. A. (2009). "Red giant clump in the Tycho-2 catalogue". Astronomy Letters. 34 (11): 785–796. arXiv:1607.00619. Bibcode:2008AstL...34..785G. doi:10.1134/S1063773708110078. S2CID 73524157. Vizier catalog entry
^ 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
^ "1 Peg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-04-10.
^ 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976. Vizier catalog entry
^ Griffin, R. F. (February 1987). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 72: 1 Pegasi B". The Observatory. 107: 1–5. Bibcode:1987Obs...107....1G.
^ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. Vizier catalog entry

Constellation of Pegasus

Stars

Bayer	α (Markab) β (Scheat) γ (Algenib) δ (Alpheratz) ε (Enif) ζ (Homam) η (Matar) θ (Biham) ι κ λ μ (Sadalbari) ν ξ ο π¹ π² ρ σ τ (Salm) υ (Alkarab) φ χ ψ
Flamsteed	1 2 3 4 5 7 9 11 12 13 14 15 16 17 18 19 20 21 23 25 28 30 31 32 33 34 35 36 37 38 39 40 41 45 51 (Helvetios) 52 55 56 57 58 59 60 61 63 64 65 66 67 69 70 71 72 73 74 75 76 77 78 79 80 82 83 85 86 87 23 Psc 34 Vul
Variable	R S U W Z RU RV RZ SV TW TY AG AQ AT AU AV AW BB BH BK BO BP BX BY DH DI DY EE EF EQ EZ GT GX HN HO HP HR HX II IK IM IP KT KU LL LO LS MS MT NV NZ OY PT V342 V343 V354 V363 V372 V376 V391
HR	19 49 8116 8219 8221 8231 8250 8257 8258 8274 8292 8325 8341 8348 8358 8359 8364 8372 8391 8397 8412 8415 8435 8441 8455 8456 8458 8460 8461 8466 8475 8482 8491 8503 8514 8543 8555 8564 8587 8604 8605 8608 8631 8638 8642 8737 8784 8788 8792 8824 8831 8833 8838 8839 8873 8922 8942 8953 8970 9039 9055 9078 9109
HD	434 204603 205011 205422 205603 206689 206793 208897 209709 210890 211076 213025 215549 215733 219196 219828 220288 220773 221170 221493 225292
Other	BD+14 4559 (Solaris) BD +17 4708 BD +28 4211 GD 246 Gl 829 Gl 880 HAT-P-8 NGC 8 NGC 18 NGC 30 PG 2131+066 PG 2303+243 PSR B2127+11C PSR B2303+30 Q2343-BX418 WASP-10 WASP-21 (Tangra) WASP-52 (Anadolu) WASP-59 WASP-60 (Morava) X2127+119 3C 454.3

Exoplanets	51 Pegasi b WASP-10b BD+14 4559 b (Pirx) TOI-5678 b HD 209458 b HR 8799 b c d e

Star
clusters

Other	Balbinot 1 Messier 15

Nebulae

Other	Pease 1

Galaxies

NGC	1 2 9 14 15 16 22 23 26 41 42 52 7033 7034 7042 7043 7053 7056 7066 7068 7074 7085 7190 7217 7236 7237 7303 7315 7317 7318 7319 7320 7320c 7331 7332 7448 7454 7457 7469 7479 7610 7619 7625 7673 7674 7678 7720 7741 7742 NGC 7752 NGC 7753 7767 7773 7800 7814
Other	BX442 CTA-102 Einstein Cross Huchra's lens IC 5337 Markarian 335 Pegasus Dwarf Irregular Galaxy Pegasus Dwarf Spheroidal Galaxy Q2343-BX418