AD Andromedae

AD Andromedae (AD And) is an eclipsing binary in the constellation Andromeda. Its maximum apparent visual magnitude is 11.2, but it shows a decrease of 0.62 magnitudes during the main eclipse and 0.58 during the secondary one. It is classified as a Beta Lyrae variable star with a period of almost one day.

AD Andromedae
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension  23h 36m 45.00656s[1]
Declination +48° 40′ 15.57327″[1]
Apparent magnitude (V) 11.2 – 11.82 variable [2]
Characteristics
Spectral type A0V[2]
Apparent magnitude (B) 11.2[3]
Apparent magnitude (V) 11.0[3]
Apparent magnitude (G) 11.0304[1]
Apparent magnitude (J) 10.897[4]
Apparent magnitude (H) 10.819[4]
Apparent magnitude (K) 10.769[4]
B−V color index 0.80[3]
Variable type β Lyrae[2]
Astrometry
Proper motion (μ) RA: −4.606±0.058 [1] mas/yr
Dec.: −3.712±0.054[1] mas/yr
Parallax (π)0.9179 ± 0.0365[1] mas
Distance3,600 ± 100 ly
(1,090 ± 40 pc)
Orbit[3]
Period (P)0.986 days
Semi-major axis (a)7.5 R☉
Inclination (i)82.6°
Periastron epoch (T)HJD 2,439,002.458
Details[3]
Primary
Mass2.76 M☉
Radius2.3 R☉
Luminosity44 L☉
Temperature9,800 K
Secondary
Mass2.7 M☉
Radius2.4 R☉
Luminosity47 L☉
Temperature9,720 K
Other designations
2MASS J23364500+4840155, BD+47 4207, TYC 3641-151-1
Database references
SIMBADdata

System

The AD Andromedae system consists of two close main sequence stars of spectral type A0V. They orbit so close to each other that they have an ellipsoidal shape induced by their gravitational interaction.[2]

The presence in this system of a third body with a minimum mass of 2.21 M☉ has been proposed; however, it should give a significant contribution to the light emitted by the system, and has not been detected yet. A possible solution is for two unseen, but less massive and luminous, stars orbiting close to each other.[3]

Variability

The orbital plane of the two stars is aligned to our line of sight, so each component eclipses the other when passing in front of it. In AD Andromedae this cycle repeats with a period 20 minutes less than one day.[2]

A cyclic variation of 14.3 years in the orbital period of this binary system has been reported, and this could be an effect of another body orbiting in this system.[3]

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References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. AD And, database entry, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250 Accessed on line 2018-10-17.
  3. Liakos, A.; Niarchos, P.; Budding, E. (March 2012). "A fresh insight into the evolutionary status and third body hypothesis of the eclipsing binaries AD Andromedae, AL Camelopardalis, and V338 Herculis". Astronomy & Astrophysics. 539: II/246. arXiv:1404.2799. Bibcode:2012A&A...539A.129L. doi:10.1051/0004-6361/201117386.
  4. Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; et al. (June 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.
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