Binary star in the constellation Andromeda
Phi Andromedae Location of φ Andromedae (upper left).
Observation dataEpoch J2000 Equinox J2000 Constellation Andromeda Right ascension 01h 09m 30.12562s [ 1] Declination +47° 14′ 30.4594″[ 1] Apparent magnitude (V)4.25[ 2] [ 3] Characteristics Spectral type B7 Ve[ 4] [ 3] U−Bcolor index −0.34[ 2] B−Vcolor index −0.07[ 2] R−Icolor index −0.05 Astrometry Radial velocity (Rv )−0.1[ 5] km/s Proper motion (μ)RA: +4.05[ 1] mas /yr Dec.: −12.43[ 1] mas /yr Parallax (π)4.55± 0.60 mas [ 1] Distance approx. 720 ly pc ) Absolute magnitude (MV )−2.41[ 6] Orbit [ 7] Companion φ And B Period (P)554.3 ± 67.1 y yr Semi-major axis (a)0.573 ± 0.051 ″Eccentricity (e)0.385 ± 0.043 Inclination (i)142.2 ± 2.8 °Longitude of the node (Ω)337.2 ± 3.2 °Periastron epoch (T)17,740 ± 1,837 HMJD Argument of periastron (ω)112.6 ± 9.1 °Details φ And A Luminosity 882[ 6] L ☉ Surface gravity (log g )3.150[ 8] cgs Temperature 13490[ 8] K Rotational velocity (v sin i )75[ 9] Age 63.1 ± 13.7 [ 10] Myr Other designations Junnanmen,φ And ,42 And ,BD +46 275HD 6811HIP 5434HR 335SAO 36972PPM 43693ADS 940[ 11] Database references SIMBAD data
Phi Andromedae , also namedJunnanmen , is abinary star [ 3] constellation ofAndromeda . This system has a combinedapparent visual magnitude of 4.25[ 2] visible to the naked eye . Based uponparallax measurements made during theHipparcos mission, this star system is located at a distance of about 720light-years (220parsecs ) from Earth.[ 1]
Phi Andromedae (Latinized from φ Andromedae, abbreviated φ And) is the star'sBayer designation .
InChinese astronomy , φ Andromedae forms the single-star asterism Jūnnánmén (軍南門 or 军南门, "Southern Military Gate").[ 12] [ 13] Star Names Keun Nan Mun , "the Camp's South Gate", and includesχ Andromedae in it,[ 14] Tian Dajiangjun (Heaven's Great General) asterism.[ 15] α Trianguli .[ 13]
TheIAU Working Group on Star Names approved the name Junnanmen for Phi Andromedae A on 25 August 2025 and it is now so entered in the IAU Catalog of Star Names.[ 16]
φ Andromedae in optical light The 4.46[ 3] Be star with astellar classification of B7 Ve, indicating that it is aB-type main sequence star that shows prominentemission lines of hydrogen in its spectrum. These emission lines come from a flatteneddecretion disk of hot gas that is orbiting the host star.[ 4] projected rotational velocity of 75 km/s.[ 9] [ 4]
The 6.06 magnitude companion star is aB-type main sequence star with a classification of B9 V. On average the two stars are separated by about 0.6 arcseconds and have an orbital period of roughly 554 years. Based upon their orbital elements, the system has a combined mass of around± 2.8[ 7]
^a b c d e f van Leeuwen, F. (November 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 . ^a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars",Communications of the Lunar and Planetary Laboratory ,4 (99): 99,Bibcode :1966CoLPL...4...99J . ^a b c d 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 . ^a b c Silaj, J.; et al. (March 2010), "A Systematic Study of Hα Profiles of Be Stars",The Astrophysical Journal Supplement ,187 (1):228– 250,Bibcode :2010ApJS..187..228S ,doi :10.1088/0067-0049/187/1/228 S2CID 122679154 . ^ Wilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities",Carnegie Institute Washington D.C. Publication , Carnegie Institution of Washington,Bibcode :1953GCRV..C......0W ^a b 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 . ^a b Muterspaugh, Matthew W.; et al. (December 2010), "The Phases Differential Astrometry Data Archive. II. Updated Binary Star Orbits and a Long Period Eclipsing Binary",The Astronomical Journal ,140 (6):1623– 1630,arXiv :1010.4043 Bibcode :2010AJ....140.1623M ,doi :10.1088/0004-6256/140/6/1623 ,S2CID 6030289 . ^a b Soubiran, Caroline; et al. (2016), "The PASTEL catalogue: 2016 version",Astronomy & Astrophysics ,591 : A118,arXiv :1605.07384 Bibcode :2016A&A...591A.118S ,doi :10.1051/0004-6361/201628497 ,S2CID 119258214 . ^a b Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars",The Astrophysical Journal ,573 (1):359– 365,Bibcode :2002ApJ...573..359A ,doi :10.1086/340590 ^ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun",Monthly Notices of the Royal Astronomical Society ,410 (1):190– 200,arXiv :1007.4883 Bibcode :2011MNRAS.410..190T ,doi :10.1111/j.1365-2966.2010.17434.x S2CID 118629873 . ^ "* phi And" .SIMBAD Centre de données astronomiques de Strasbourg . Retrieved2012-06-25 .^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 9 日 Archived 2011-05-22 at theWayback Machine ^a b "Junnanmen (军南门)" .All Skies Encyclopaedia .IAU Working Group on Star Names . Retrieved10 June 2025 .^ Allen, R. H. (1899),Star-names and Their Meanings ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 10 日 Archived 2011-07-16 at theWayback Machine ^ "IAU Catalog of Star Names" . Retrieved26 August 2025 .
