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2 Andromedae, abbreviated 2 And, is a binary starcite-ref-rica-romero2010-3-4[3] system in the northern constellation of Andromeda. 2 Andromedae is the Flamsteed designation. It is a faint star system but visible to the naked eye with a combined apparent visual magnitude of 5.09.cite-ref-anderson2012-2-2[2] Based upon an annual parallax shift of 7.7 mas,cite-ref-van-leeuwen2007-1-5[1] it is located 420 light years away. The binary nature of the star was discovered by American astronomer Sherburne Wesley Burnham at Lick Observatory in 1889.cite-ref-burnham1894-12-0[12] The pair orbit each other over a period of 74 years with a high eccentricity of 0.8.cite-ref-rica-romero2010-3-5[3]

The magnitude 5.26cite-ref-rica-romero2010-3-6[3] primary, designated component A, is an A-type main-sequence star based on a stellar classification of A1Vcite-ref-abt1995-4-1[4] or A2V,cite-ref-rica-romero2010-3-7[3] although it may have already left the main sequence.cite-ref-jerzykiewicz2015-7-8[7] It was identified as a candidate Lambda Boötis star, but this was ruled out by Paunzen et al. (2003) as it doesn't match the typical characteristics of these objects.cite-ref-paunzen2003-13-0[13] Although 2 Andromedae does not display a significant infrared excess, it is a shell star that displays varying absorption features due to circumstellar dust grains. This may indicate it has an orbiting debris disk containing gas that is being viewed edge-on.cite-ref-roberge2008-14-0[14] The star is about 100 million years old and is spinning rapidly with a projected rotational velocity of 212 km/s.cite-ref-zorec2012-8-1[8]

The magnitude 7.43cite-ref-rica-romero2010-3-8[3] secondary companion, component B, is a suspected variable star and may be a Delta Scuti variable.cite-ref-rica-romero2010-3-9[3] Alternatively, it may be an ellipsoidal variable with a brown dwarf companion.cite-ref-jerzykiewicz2015-7-9[7] It is an F-type main-sequence star with a class of F1V/F4.cite-ref-rica-romero2010-3-10[3]

• References

• External links

cite-note-van-leeuwen2007-11. citerefvan-leeuwen2007van 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

cite-note-anderson2012-22. citerefandersonfrancis2012Anderson, 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.

cite-note-rica-romero2010-33. citerefrica-romero2010Rica Romero, F. M. (2010). "Orbital elements for eight binaries. Study of the nature of wide components. I" (PDF). Revista Mexicana de Astronomía y Astrofísica. 46: 263–277. Bibcode:2010RMxAA..46..263R. Archived from the original (PDF) on 2014-02-25. Retrieved 2014-09-01.

cite-note-abt1995-44. citerefabtmorrell1995Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.

cite-note-egubv-51. citerefmermilliod1986Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.

cite-note-gontcharov-62. citerefgontcharov2006Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.

cite-note-jerzykiewicz2015-77. citerefjerzykiewiczhandlerdaszy-ska-daszkiewiczpigulski2015Jerzykiewicz, M.; et al. (2015). "The 2003–2004 multisite photometric campaign for the β Cephei and eclipsing star 16 (EN) Lacertae with an appendix on 2 Andromedae, the variable comparison star". Monthly Notices of the Royal Astronomical Society. 454 (1): 724–740. arXiv:1508.05250. Bibcode:2015MNRAS.454..724J. doi:10.1093/mnras/stv1958. S2CID 119220117.

cite-note-zorec2012-88. citerefzorecroyer2012Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789.

cite-note-gullikson2016-93. citerefgulliksonkrausdodson-robinson2016Gullikson, Kevin; et al. (August 2016). "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars". The Astronomical Journal. 152 (2): 13. arXiv:1604.06456. Bibcode:2016AJ....152...40G. doi:10.3847/0004-6256/152/2/40. S2CID 119179065. 40.

cite-note-simbad-104. "2 And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 11, 2018.

cite-note-mast-115. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.

cite-note-burnham1894-1212. ↑ citerefburnham1894Burnham, S. W. (1894). "Sixteenth Catalogue of New Double Stars Discovered at the Lick Observatory". Publications of Lick Observatory. 2: 197–205. Bibcode:1894PLicO...2..197B.

cite-note-paunzen2003-1313. ↑ citerefpaunzenkampweisswiesemeyer2003Paunzen, E.; et al. (June 2003). "A study of lambda Bootis type stars in the wavelength region beyond 7000 Å". Astronomy and Astrophysics. 404 (2): 579–591. arXiv:astro-ph/0303191. Bibcode:2003A&A...404..579P. doi:10.1051/0004-6361:20030284.

cite-note-roberge2008-1414. ↑ citerefrobergeweinberger2008Roberge, Aki; Weinberger, Alycia J. (March 2008). "Debris Disks around Nearby Stars with Circumstellar Gas". The Astrophysical Journal. 676 (1): 509–517. arXiv:0711.4561. Bibcode:2008ApJ...676..509R. doi:10.1086/527314. S2CID 18407657.

• Image 2 Andromedae