The observedspectral type of both stars in this system is G5, and one of them is amain sequence star very similar to the sun.[3] They are orbiting so close that their envelopes touch each other. This is a dynamically stable phase that should last until one of the two stars leaves the main sequence.
The system could also host a third body with an orbital period of 19,046 days, with a minimum mass of 0.007M☉ and an eccentricity of 0.22, but not all data collected in time are consistent with this hypothesis.[7]
The two stars eclipse each other during their orbit, but they have an elongated shape so they show a constant variation instead of discrete eclipses. Anyway, a periodicity can be seen clearly, but it changes with time; the period shows a long-term trend and a periodic modulation of 7,000 days. The effects responsible for this behaviour could be a third body in the system, magnetic interaction between two stars,[9] mass transfer from one star to the other, mass loss of the system, and recently even an internal mechanism in the touching envelopes have been proposed.[10]
^abcdAB And, database entry, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), N. N. Samus, O. V. Durlevich, et al.,CDS IDII/250 Accessed on line 2018-10-22.
^abcHøg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars",Astronomy & Astrophysics,355:L27–L30,Bibcode:2000A&A...355L..27H.
^abcCutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003)."VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)".CDS/ADC Collection of Electronic Catalogues.2246: II/246.Bibcode:2003yCat.2246....0C.
^abKarami, K.; Ghaderi, K.; Mohebi, R.; Sadeghi, R.; Soltanzadeh, M. M. (June 2009), "Velocity-Curve Analysis of the Spectroscopic Binary Stars V373 Cas, V2388 Oph, V401 Cyg, GM Dra, V523 Cas, AB And and HD 141929 by Artificial Neural Networks",Publications of the Astronomical Society of Australia,26 (2):121–127,arXiv:0907.4411,Bibcode:2009PASA...26..121K,doi:10.1071/AS09010,S2CID119247525.
^abBorkovits, T.; Elkhateeb, M. M.; Csizmadia, Cz.; Nuspl, J.; Bíró, I. B.; Hegedüs, T.; Csorvási, R. (2005), "Indirect evidence for short period magnetic cycles in W UMa stars. Period analysis of five overcontact systems.",Astronomy & Astrophysics,441 (3):1087–1097,arXiv:astro-ph/0507228,Bibcode:2005A&A...441.1087B,doi:10.1051/0004-6361:20052805.
