Astronomy:V1191 Cygni

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Short description: Star in the constellation Cygnus
V1191 Cygni
V1191CygLightCurve.png
A visual band light curve for V1191 Cygni, adapted from Ostadnezhad et al. (2014)[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Cygnus
Right ascension  20h 16m 50.8045s[2]
Declination +41° 57′ 41.360″[2]
Apparent magnitude (V) 10.99[3]
Characteristics
Spectral type F6V + G5V[4]
Apparent magnitude (B) 11.41[3]
Apparent magnitude (R) 10.55[5]
Apparent magnitude (I) 10.06[6]
Apparent magnitude (J) 9.82[7]
Apparent magnitude (H) 9.56[7]
Apparent magnitude (K) 9.51[7]
B−V color index 0.62[8]
Variable type W UMa[9]
Astrometry
A
Proper motion (μ) RA: 38.4 ± 1.7[3] mas/yr
Dec.: 25.1 ± 1.6[3] mas/yr
Distance278 ± 31[10] pc
Absolute magnitude (MV)3.82[10]
B
Absolute magnitude (MV)5.73[10]
Orbit
Period (P)0.3134 d[11]
Semi-major axis (a)2.182 R☉[12]
Details
A
Mass1.29 ± 0.08[10] M☉
Radius1.31 ± 0.18[10] R☉
Luminosity (bolometric)2.71 ± 0.44[10] L☉
Surface gravity (log g)4.31[10] cgs
Temperature6500[10] K
Age3.85 ± 0.21[12] Gyr
B
Mass0.13 ± 0.01[10] M☉
Radius0.52 ± 0.15[10] R☉
Luminosity (bolometric)0.46 ± 0.08[10] L☉
Surface gravity (log g)4.12[10] cgs
Temperature6610 ± 200[10] K
Age3.85 ± 0.21[12] Gyr
Other designations
GSC 03159-01512, 2MASS J20165081+4157413, SBC9 2996, TYC 3159-1512-1
Database references
SIMBADdata

V1191 Cygni is the variable star designation for an overcontact binary star system in the constellation Cygnus.[13] First found to be variable in 1965, it is a W Ursae Majoris variable with a maximum apparent magnitude 10.82. It drops by 0.33 magnitudes during primary eclipses with a period of 0.3134 days, while dropping by 0.29 magnitudes during secondary eclipses.[11] The primary star, which is also the cooler star, appears to have a spectral type of F6V, while the secondary is slightly cooler with a spectral type of G5V.[4] With a mass of 1.29 solar masses and a luminosity of 2.71 solar luminosities, it is slightly more massive and luminous than the sun, while the secondary is only around 1/10 as massive and less than half as luminous. With a separation of 2.20 solar radii, the mass transfer of about 2×10−7 solar masses per year from the secondary to the primary is one of the highest known for a system of its type.[10]

V1191 Cygni is a W-type W UMa variable,[8] meaning that the primary eclipse occurs when the less-massive component is eclipsed by the larger, more massive component, although the masses are unusually different for such a system.[14] The current period is very short for a system of its spectral type, suggesting that the stars are relatively small for their mass and age,[14] which is likely around 3.85 billion years.[12] The pair's orbital period is increasing at a rate of over 4×10−7 days per year, one of the fastest known rates among contact binary systems,[8] likely due to the high rate of mass transfer. In addition to the period increase, there is cyclic period change of 0.023 days over 26.7 years, caused by either a third body with a mass of 0.77 solar masses or magnetic activity cycles. The mass transfer will likely eventually cause the system to evolve into a single star with a very high rotation rate.[13]

References

  1. ↑ Ostadnezhad, S.; Delband, M.; Hasanzadeh, A. (August 2014). "Photometry, period variations and light curve analysis of eclipsing binary V1191 Cyg". New Astronomy 31: 14–19. doi:10.1016/j.newast.2014.02.001. Bibcode: 2014NewA...31...14O. https://ui.adsabs.harvard.edu/abs/2014NewA...31...14O. Retrieved 22 December 2021. 
  2. ↑ 2.0 2.1 Hog, E.; Kuzmin, A.; Bastian, U.; Fabricius, C.; Kuimov, K.; Lindegren, L.; Makarov, V. V.; Roeser, S. (1998). "The TYCHO Reference Catalogue". Astronomy and Astrophysics 335: L65. Bibcode: 1998A&A...335L..65H. 
  3. ↑ 3.0 3.1 3.2 3.3 Høg, E. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. doi:10.1888/0333750888/2862. Bibcode: 2000A&A...355L..27H. 
  4. ↑ 4.0 4.1 Avvakumova, E.A.; Malkov, O.Yu.; Kniazev, A.Yu. (2013). "Eclipsing variables: Catalogue and classification". Astronomische Nachrichten 334 (8): 860–865. doi:10.1002/asna.201311942. Bibcode: 2013AN....334..860A. 
  5. ↑ Ivanov, G. A. (2008). "Catalogue of stars with high-proper motions - version 2". Kinematika I Fizika Nebesnykh Tel 24: 480. Bibcode: 2008KFNT...24..480I. 
  6. ↑ Droege, Thomas F.; Richmond, Michael W.; Sallman, Michael P.; Creager, Robert P. (2006). "TASS Mark IV Photometric Survey of the Northern Sky". Publications of the Astronomical Society of the Pacific 118 (850): 1666–1678. doi:10.1086/510197. Bibcode: 2006PASP..118.1666D. 
  7. ↑ 7.0 7.1 7.2 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. 
  8. ↑ 8.0 8.1 8.2 Pribulla, T.; Vaňko, M.; Chochol, D. R.; Parimucha, Š.; Baluďanský, D. (2005). "Ccd Photometry of the Neglected Contact Binaries V344 Lac and V1191 Cyg". Astrophysics and Space Science 296 (1–4): 281–284. doi:10.1007/s10509-005-4831-2. Bibcode: 2005Ap&SS.296..281P. 
  9. ↑ Mayer, P (1965). "Two new variable stars in the Cygnus". Bulletin of the Astronomical Institute of Czechoslovakia 16: 255–256. Bibcode: 1965BAICz..16..255M. 
  10. ↑ 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 10.10 10.11 10.12 10.13 Ulaş, B.; Kalomeni, B.; Keskin, V.; Köse, O.; Yakut, K. (2012). "Marginally low mass ratio close binary system V1191 Cyg". New Astronomy 17 (1): 46–49. doi:10.1016/j.newast.2011.06.002. Bibcode: 2012NewA...17...46U. 
  11. ↑ 11.0 11.1 Malkov, O. Yu.; Oblak, E.; Snegireva, E. A.; Torra, J. (2006). "A catalogue of eclipsing variables". Astronomy and Astrophysics 446 (2): 785–789. doi:10.1051/0004-6361:20053137. Bibcode: 2006A&A...446..785M. 
  12. ↑ 12.0 12.1 12.2 12.3 Yildiz, M. (2013). "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. 
  13. ↑ 13.0 13.1 Zhu, L. Y.; Qian, S. B.; Soonthornthum, B.; He, J. J.; Liu, L. (2011). "Deep, Low Mass Ratio Overcontact Binary Systems. Xi. V1191 Cygni". The Astronomical Journal 142 (4): 124. doi:10.1088/0004-6256/142/4/124. Bibcode: 2011AJ....142..124Z. 
  14. ↑ 14.0 14.1 Rucinski, S. M.; Pribulla, T.; Mochnacki, S. W.; Liokumovich, E.; Lu, W.; Debond, H.; De Ridder, A.; Karmo, T. et al. (2008). "Radial Velocity Studies of Close Binary Stars. Xiii". The Astronomical Journal 136 (2): 586–593. doi:10.1088/0004-6256/136/2/586. Bibcode: 2008AJ....136..586R. 



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