| u-b =
| j-h =
| j-k =
| variable = EW
}}{{Starbox astrometry
| radial_v= {{val|-27.53|0.67}}[12]
| prop_mo_ra={{val|107.923|0.046}} [1]
| prop_mo_dec={{val|-53.357|0.036}}[1]
| parallax= 11.7027
| p_error= 0.0367
| parallax_footnote = [1]
| dist_ly =
| dist_pc =
| absmag_v =
| absmag_bol =
}}{{Starbox orbit
| reference = [16]
| primary =
| name =
| period_unitless = 0.3319 days
| axis =
| axis_unitless = 2.308 {{solar radius}}[17]
| eccentricity = {{val|0.002|0.001}}
| inclination =
| node =
| periastron =
| periarg = {{val|40|5}}
| periarg_primary = {{val|220|5}}
| k1 = {{val|233|1}}
| k2 = {{val|133|1}}
}}{{Starbox detail
| source = [18]
| component1 = Primary
| mass = 1.04
| radius = 1.03
| radius_km =
| luminosity =
| luminosity_bolometric =
| luminosity_visual =
| habitable_inner =
| habitable_outer =
| gravity = 4.392[19]
| temperature = 5,798
| metal =
| metal_fe =
| rotation =
| rotational_velocity =
| age =
| age_myr =
| age_gyr = {{val|5.53|2.00}}[17]
| component2 = Secondary
| mass2 = 0.60
| radius2 = 0.78
| radius_km2 =
| luminosity2 =
| luminosity_bolometric2 =
| luminosity_visual2 =
| habitable_inner2 =
| habitable_outer2 =
| gravity2 = 4.347[19]
| temperature2 = 5,450
| metal2 =
| metal2_fe =
| rotation2 =
| rotational_velocity2 =
| age2 =
| age_myr2 =
| age_gyr2 = {{val|5.53|2.00}}[17]
}}{{Starbox catalog
| names=2MASS J23113209+3653351, BD+36 5017, HIP 114508, SAO 73069, TYC 2763-904-1}}{{Starbox reference |
}}{{Starbox end}}AB Andromedae (AB And) is a binary star in the constellation Andromeda. Its maximum apparent visual magnitude is 9.49 but shows a variation in brightness down to a magnitude of 10.46 in a periodic cycle of roughly 8 hours. The observed variability is typical of W Ursae Majoris variable stars,[ so the two stars in this system form a contact binary.]
System
The observed spectral type of both stars in this system is G5, and one of them is a main sequence star very similar to the sun.[ 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 0.007 {{solar mass}} and an eccentricity of 0.22, but not all data collected in time are consistent with this hypothesis.[16]
Variability
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,[18] mass transfer from one star to the another, mass loss of the system, and recently even an internal mechanism in the touching envelopes have been proposed.[19]
References
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6. ^1 2 3 {{citation | last1=Yıldız | first=M. | title=Origin of W UMa-type contact binaries - age and orbital evolution | journal=Monthly Notices of the Royal Astronomical Society | volume=437 | issue=1 | pages=185-194 | year=2014 | bibcode=2014MNRAS.437..185Y | postscript=. }}
7. ^1 2 3 {{citation | last1=Liu | first1=L. | last2=Qian | first2=S. B. | last3=Xiong | first3=X. | title=A new mechanism of long-term period variations for W UMa-type contact binaries | journal=Monthly Notices of the Royal Astronomical Society | volume=474 | issue=4 | pages=5199-5205 | year=2018 | bibcode=2018MNRAS.474.5199L | postscript=. }}