Phi Andromedae (φ Andromedae, φ And) is the Bayer designation for a binary star[3] system near the border of the northern constellation of Andromeda. This system has a combined apparent visual magnitude of 4.25[2] and is visible to the naked eye. Based upon parallax measurements made during the Hipparcos mission, this star system is located at a distance of about 720 light-years (220 parsecs) from Earth.[1] With χ And it forms the Chinese asterism 軍南門 (Keun Nan Mun, Mandarin jūnnánmén), "the South Gate of the Camp".[12][13]
The 4.46[3] magnitude primary component is a Be star with a stellar classification of B7Ve, indicating that it is a B-type main sequence star that shows prominent emission lines of hydrogen in its spectrum. These emission lines come from a flattened decretion disk of hot gas that is orbiting the host star.[4] The star is rotating rapidly with a projected rotational velocity of 75km/s.[9] The pole of the star is inclined around 20° to the line of sight from the Earth.[4]
The 6.06 magnitude companion star is a B-type main sequence star with a classification of B9V. On average the two stars are separated by about 0.6arcseconds and have an orbital period of roughly 554 years. Based upon their orbital elements, the system has a combined mass of around 6.5 ± 2.8[7] times the mass of the Sun.
Johnson, H. L.; etal. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
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, S2CID14878976.
Silaj, J.; etal. (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.
Wilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W. Accessed 2007-05-14.
Muterspaugh, Matthew W.; etal. (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, S2CID6030289.
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, S2CID118629873.
"* phi And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-06-25.
Allen, R. H. (1899), Star-names and Their Meanings, New York: G. E. Stechart, p.39.
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