Astronomy:AB Andromedae

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Short description: Binary star in the Andromeda constellation
AB Andromedae
ABAndLightCurve.png
The visual band light curve of AB Andromedae, adapted from Parimucha et al.[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Andromeda
Right ascension  23h 11m 32.08609s[2]
Declination +36° 53′ 35.10721″[2]
Apparent magnitude (V) 9.49 ( – 10.32) – 10.46[3]
Characteristics
Spectral type G5+G5V[3]
Apparent magnitude (B) 10.62[4]
Apparent magnitude (V) 9.675[4]
Apparent magnitude (G) 9.6953[2]
Apparent magnitude (J) 8.172[5]
Apparent magnitude (H) 7.805[5]
Apparent magnitude (K) 7.665[5]
B−V color index 0.9163[4]
Variable type EW
Astrometry
Radial velocity (Rv)−27.53±0.67[6] km/s
Proper motion (μ) RA: 107.923±0.046 [2] mas/yr
Dec.: −53.357±0.036[2] mas/yr
Parallax (π)11.7027 ± 0.0367[2] mas
Distance278.7 ± 0.9 ly
(85.5 ± 0.3 pc)
Orbit[7]
Period (P)0.3319 days
Semi-major axis (a)2.308 R☉[8]
Eccentricity (e)0.002±0.001
Argument of periastron (ω)
(secondary)		40±5°
Argument of periapsis (ω)
(primary)		220±5°
Semi-amplitude (K1)
(primary)		233±1 km/s
Semi-amplitude (K2)
(secondary)		133±1 km/s
Details[9]
Primary
Mass1.04 M☉
Radius1.03 R☉
Surface gravity (log g)4.392[10] cgs
Temperature5,798 K
Age5.53±2.00[8] Gyr
Secondary
Mass0.60 M☉
Radius0.78 R☉
Surface gravity (log g)4.347[10] cgs
Temperature5,450 K
Age5.53±2.00[8] Gyr
Other designations
2MASS J23113209+3653351, BD+36 5017, HIP 114508, SAO 73069, TYC 2763-904-1
Database references
SIMBADdata

AB Andromedae (AB And) is a binary star in the constellation Andromeda. Paul Guthnick and Richard Prager discovered that the star is an eclipsing binary in 1927.[11][12] 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,[3] 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.[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 0.007 M☉ and an eccentricity of 0.22, but not all data collected in time are consistent with this hypothesis.[7]

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,[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]

References

  1. ↑ Parimucha, Stefan; Pribulla, Theodor; Vanko, Martin (January 2000). "New Photoelectric Light Curves of AB Andromedae". Information Bulletin on Variable Stars 4834: 1. Bibcode: 2000IBVS.4834....1P. http://articles.adsabs.harvard.edu/pdf/2000IBVS.4834....1P. Retrieved 6 October 2021. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 AB 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 2018-10-22.
  4. ↑ 4.0 4.1 4.2 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy & Astrophysics 355: L27–L30, Bibcode: 2000A&A...355L..27H. 
  5. ↑ 5.0 5.1 5.2 Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E. et al. (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. http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=II/246. 
  6. ↑ Bilir, S.; Karataș, Y.; Demircan, O.; Eker, Z. (February 2005), "Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation", Monthly Notices of the Royal Astronomical Society 357 (2): 497–517, doi:10.1111/j.1365-2966.2005.08609.x, Bibcode: 2005MNRAS.357..497B. 
  7. ↑ 7.0 7.1 Karami, 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, doi:10.1071/AS09010, Bibcode: 2009PASA...26..121K. 
  8. ↑ 8.0 8.1 8.2 Yıldız, M. (2014), "Origin of W UMa-type contact binaries - age and orbital evolution", Monthly Notices of the Royal Astronomical Society 437 (1): 185–194, doi:10.1093/mnras/stt1874, Bibcode: 2014MNRAS.437..185Y. 
  9. ↑ 9.0 9.1 Borkovits, 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, doi:10.1051/0004-6361:20052805, Bibcode: 2005A&A...441.1087B. 
  10. ↑ 10.0 10.1 10.2 Liu, L.; Qian, S. B.; Xiong, X. (2018), "A new mechanism of long-term period variations for W UMa-type contact binaries", Monthly Notices of the Royal Astronomical Society 474 (4): 5199–5205, doi:10.1093/mnras/stx3138, Bibcode: 2018MNRAS.474.5199L. 
  11. ↑ Oosterhoff, P. Th. (February 1929). "Epochs of minimum of AB Andromedae". Bulletin of the Astronomical Institutes of the Netherlands 5: 37–40. Bibcode: 1929BAN.....5...37O. https://articles.adsabs.harvard.edu/pdf/1929BAN.....5...37O. Retrieved 24 February 2023. 
  12. ↑ Guthnick, P.; Prager, R. (November 1927). "Benennung von veränderlichen Sternen". Astronomische Nachrichten 231 (10): 161–172. doi:10.1002/asna.19272311002. Bibcode: 1927AN....231..161G. https://onlinelibrary.wiley.com/doi/pdf/10.1002/asna.19272311002. Retrieved 24 February 2023. 



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