Astronomy:AW Ursae Majoris

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Short description: Variable star in the constellation Ursa Major
AW Ursae Majoris
AWUMaLightCurve.png
A light curve for AW Ursae Majoris, plotted from TESS data[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Ursa Major
Right ascension  11h 30m 04.316s[2]
Declination +29° 57′ 52.67″[2]
Apparent magnitude (V) Max: 6.83
Min1: 7.13
Min2: 7.08[3]
Characteristics
Spectral type F0V–F1V[4]
Variable type Contact W UMa[3]
Astrometry
Radial velocity (Rv)−17.0±1.57[5] km/s
Proper motion (μ) RA: −84.298[2] mas/yr
Dec.: −198.900[2] mas/yr
Parallax (π)14.7836 ± 0.0295[2] mas
Distance220.6 ± 0.4 ly
(67.6 ± 0.1 pc)
Absolute magnitude (MV)2.74±0.12[4]
Orbit[6]
Period (P)0.438732 d
Semi-major axis (a)2.74 ± 0.93 Gm (0.0183 ± 0.0062 AU)
Eccentricity (e)0.00 (assumed)
Inclination (i)78.3[7]°
Periastron epoch (T)2,443,974.198 JD
Argument of periastron (ω)
(secondary)		0.00°
Semi-amplitude (K1)
(primary)		29±8 km/s
Semi-amplitude (K2)
(secondary)		423±80 km/s
Details
Primary
Mass1.79±0.14[8] M☉
Radius1.49[9] R☉
Luminosity5.9 – 6.5[4] L☉
Temperature6.980[4] K
Metallicity [Fe/H]−0.01±0.08[9] dex
Rotational velocity (v sin i)181.4[9] km/s
Age3.26±0.17[8] Gyr
Secondary
Mass0.14±0.01[8] M☉
Radius≤ 0.678[10] R☉
Luminosity0.57 – 0.73[4] L☉
Temperature6,201 – 6,901[4] K
Other designations
Paczynski’s star[9], AW UMa, BD+30°2163, FK5 2916, GC 15772, HD 99946, HIP 56109, SAO 62579, PPM 101203, WDS J11301+2958A, LTT 13131[11]
Database references
SIMBADdata

AW Ursae Majoris is a binary star system in the northern circumpolar constellation of Ursa Major, abbreviated AW UMa. It is an A-type W Ursae Majoris variable[7] (W UMa) with an apparent visual magnitude of 6.83, which is near the lower limit of visibility to the naked eye. This is an eclipsing binary with the brightness dropping to magnitude 7.13 during the primary eclipse and to 7.08 with the secondary eclipse.[3] Parallax measurements give a distance estimate of 221 light years from the Sun. It is drifting closer to the Sun with a radial velocity of approximately −17 km/s.[5] The system has a high proper motion, traversing the celestial sphere at the rate of 0.216 arc second per annum.[12]

While observing the variable star TU UMa in 1964, B. Paczyński noted that the comparison star BD +30°2163 was itself variable. The latter was determined to be a W UMa-type eclipsing binary with a period of 0.438727 days. A flat light curve during the minimum suggested the primary eclipse is full or annular.[13] In 1972, S. W. Mochnacki and N. A. Doughty modelled the system and determined a very low mass ratio of 0.079±0.08 for the pair, indicating that the secondary has 8% of the mass of the primary.[14]

E. J. Woodward and associates in 1980 found evidence of a recent period change for the system and suspected an intrinsic variability based on mismatches in the light curves over time.[15] In 1981, B. J. McLean made radial velocity measurements of the system and used them to compute orbital elements.[6] R. K. Srivastava confirmed period changes in the range of 10−6 to 10−7 days occurred during the interval from 1963 to 1988.[16] Further period changes were noted in 1997.[17] In 1999, T. Pribulla and associates proposed that observed velocity changes to the system are the result of an undetected third component. This would have 0.85±0.13 times the mass of the Sun and an orbital period of 398 days. Period changes to the binary are attributed to mass transfer.[7]

B. Paczyński and associates in 2007 proposed an evolutionary model for the system. They suggested that the current secondary was the original primary for the system, and as a result was the first to evolve off the main sequence and expand. Most of the star's mass was then transferred to the companion, until the system reached the current mass ratio. This left the current secondary with a helium core and much of its outer hydrogen envelope stripped away. Because of the mass acquisition, the present day primary now resembles a zero age main sequence star.[10] In 2008, T. Pribulla and S. M. Rucinski called into question the assumption that this is a contact binary system, suggesting instead that the pair share a luminous equatorial belt.[4]

O. J. Eggen in 1967 noted that a nearby star is a common proper motion companion to AW UMa,[18] which may form a tertiary component to this system. This magnitude 9.41 star is located at an angular separation of 67.2″ from the binary pair.[19] The star has a parallax of 14.7 mas, indicating a distance of 222 light years, and is modelled to be a middle-aged main sequence star similar to the Sun.[20]

References

  1. ↑ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html, retrieved 30 September 2022. 
  2. ↑ 2.0 2.1 2.2 2.3 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 Samus, N. N. et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Pribulla, T.; Rucinski, S. M. (May 2008), "Radial velocity mapping of Paczyński's star AW UMa: not a contact binary", Monthly Notices of the Royal Astronomical Society 386 (1): 377–389, doi:10.1111/j.1365-2966.2008.13033.x, Bibcode: 2008MNRAS.386..377P. 
  5. ↑ 5.0 5.1 Bilir, S. et al. (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. 
  6. ↑ 6.0 6.1 McLean, B. J. (June 1981), "Radial velocities for contact binary systems. I. W UMa and AW UMa", Monthly Notices of the Royal Astronomical Society 195: 931–938, doi:10.1093/mnras/195.4.931, Bibcode: 1981MNRAS.195..931M. 
  7. ↑ 7.0 7.1 7.2 Pribulla, T. et al. (May 1999), "The contact binary AW Ursae Majoris as a member of a multiple system", Astronomy and Astrophysics 345: 137–148, Bibcode: 1999A&A...345..137P. 
  8. ↑ 8.0 8.1 8.2 Yıldız, M. (January 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 9.2 9.3 Rucinski, Slavek M. (February 2015), "Time Sequence Spectroscopy of AW UMa. The 518 nm Mg i Triplet Region Analyzed With Broadening Functions", The Astronomical Journal 149 (2): 14, doi:10.1088/0004-6256/149/2/49, 49, Bibcode: 2015AJ....149...49R. 
  10. ↑ 10.0 10.1 Paczyński, B. et al. (July 2007), "A model of AW UMa", Monthly Notices of the Royal Astronomical Society 378 (3): 961–965, doi:10.1111/j.1365-2966.2007.11822.x, Bibcode: 2007MNRAS.378..961P. 
  11. ↑ "AW UMa". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=AW+UMa. 
  12. ↑ Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal 129 (3): 1483–1522, doi:10.1086/427854, Bibcode: 2005AJ....129.1483L. 
  13. ↑ Paczynski, B. (February 1964), "BD +30 2163, a new W UMa variable", Astronomical Journal 69: 124–130, doi:10.1086/109240, Bibcode: 1964AJ.....69..124P. 
  14. ↑ Mochnacki, S. W.; Doughty, N. A. (1972), "A model for the totally eclipsing W Ursae Majoris system AW UMa", Monthly Notices of the Royal Astronomical Society 156: 51, doi:10.1093/mnras/156.1.51, Bibcode: 1972MNRAS.156...51M. 
  15. ↑ Woodward, E. J. et al. (January 1980), "Analyses of new light curve of AW Ursae Majoris", Astronomical Journal 85: 50–54, doi:10.1086/112635, Bibcode: 1980AJ.....85...50W. 
  16. ↑ Srivastava, R. K. (April 1989), "Period Study of AW-Ursae", Astrophysics and Space Science 154 (2): 179–187, doi:10.1007/BF00642802, Bibcode: 1989Ap&SS.154..179S. 
  17. ↑ Pribulla, T.; Chochol, D.; Rovithis, P.; Rovithis-Livaniou, H. (February 1997), "Sudden Period Change in the Contact Binary AW UMa?", Information Bulletin on Variable Stars 4435: 1, Bibcode: 1997IBVS.4435....1P. 
  18. ↑ Eggen, O. J. (1967), "Contact binaries, II", Memoirs of the Royal Astronomical Society 70: 111, Bibcode: 1967MmRAS..70..111E.  See the entry for BD +30°2163.
  19. ↑ Lépine, Sébastien; Bongiorno, Bethany (March 2007), "New Distant Companions to Known Nearby Stars. II. Faint Companions of Hipparcos Stars and the Frequency of Wide Binary Systems", The Astronomical Journal 133 (3): 889–905, doi:10.1086/510333, Bibcode: 2007AJ....133..889L. 
  20. ↑ Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.

Further reading

  • Eaton, Joel A. (March 2016), "AW Ursae Majoris: a semidetached mass-transferring system indeed?", Monthly Notices of the Royal Astronomical Society 457 (1): 836–843, doi:10.1093/mnras/stv3013, Bibcode: 2016MNRAS.457..836E. 
  • Rucinski, S. M. et al. (November 2013), "AW UMa observed with MOST satellite", Information Bulletin on Variable Stars 6079: 1, Bibcode: 2013IBVS.6079....1R. 
  • Rucinski, S. M. (November 1992), "Spectral-Line Broadening Functions of WUMa-Type Binaries. I. AW UMa", Astronomical Journal 104: 1968, doi:10.1086/116372, Bibcode: 1992AJ....104.1968R. 
  • Demircan, O. et al. (September 1992), "A period study of AW UMa", Astronomy and Astrophysics 263: 165–171, Bibcode: 1992A&A...263..165D. 
  • Bakos, G. A. et al. (November 1991), "New Photometry of AW UMa and Interpretation of Time Dependent Variations of Observed Light Curves", Bulletin of the Astronomical Institute of Czechoslovakia 42: 331, Bibcode: 1991BAICz..42..331B. 
  • Derman, E. et al. (November 1990), "AW UMa is in Active Phase of Mass Transfer", Information Bulletin on Variable Stars 3540: 1, Bibcode: 1990IBVS.3540....1D. 
  • Bakos, G. A. et al. (1990), "A new model of AW UMa", Contributions of the Astronomical Observatory Skalnate Pleso 20: 57, Bibcode: 1990CoSka..20...57B. 
  • Srivastava, R. K.; Padalia, T. D. (March 1986), "Photoelectric Study of AW UMa", Astrophysics and Space Science 120 (1): 121–131, doi:10.1007/BF00653904, Bibcode: 1986Ap&SS.120..121S. 
  • Rensing, M. J. et al. (May 1985), "The mass of AW Ursae Majoris", Astronomical Journal 90: 767–772, doi:10.1086/113785, Bibcode: 1985AJ.....90..767R. 
  • Rucinski, S. M. et al. (May 1984), "IUE observations of two extremes among contact binaries : AW Ursae Majoris and SW Lacertae.", Monthly Notices of the Royal Astronomical Society 208 (2): 309–321, doi:10.1093/mnras/208.2.309, Bibcode: 1984MNRAS.208..309R. 
  • Anderson, L. et al. (July 1983), "Stellar images derived from rotation broadening : AW Ursae Majoris", Astrophysical Journal 270: 200–210, doi:10.1086/161111, Bibcode: 1983ApJ...270..200A. 
  • Hrivnak, B. J. (September 1982), "A photometric study and analysis of AW UMa", Astrophysical Journal 260: 744–754, doi:10.1086/160294, Bibcode: 1982ApJ...260..744H. 
  • Kurpinska-Winiarska, Maria (September 1980), "Period Change of AW Ursae Maioris", Information Bulletin on Variable Stars 1843: 1, Bibcode: 1980IBVS.1843....1K. 
  • Mikolajewska, J.; Mikolajewski, M. (July 1980), "New BV Light Curves and Minima of the Eclipsing Binaries W UMa, AW UMa and 44i Boo", Information Bulletin on Variable Stars 1812: 1, Bibcode: 1980IBVS.1812....1M. 
  • Istomin, L. F. et al. (June 1980), "The Light Variation and Orbital Elements of AW UMa", Information Bulletin on Variable Stars 1802: 1, Bibcode: 1980IBVS.1802....1I. 
  • Hart, K. et al. (November 1979), "Photoelectric Minima of AW UMa and W UMa", Information Bulletin on Variable Stars 1701: 1, Bibcode: 1979IBVS.1701....1H. 
  • Al-Naimiy, H. M. K. (June 1978), "Synthetic Light Curves of Two Eclipsing Binary Systems, U Sge and AW UMa", Astrophysics and Space Science 56 (1): 219–238, doi:10.1007/BF00643469, Bibcode: 1978Ap&SS..56..219A. 
  • Ferland, G. J.; McMillan, R. S. (September 1976), "Photoelectric Differential Photometry of the Contact Binary AW UMa", Information Bulletin on Variable Stars 1176: 1, Bibcode: 1976IBVS.1176....1F. 
  • Piirola, V. (November 1975), "About the Intrinsic Polarization of AW UMa", Information Bulletin on Variable Stars 1060: 1, Bibcode: 1975IBVS.1060....1P. 
  • Dworak, T. Z.; Kurpinska, M. (1975), "Photoelectric Observations of the Variable AW UMa", Acta Astronomica 25 (1): 417–426, Bibcode: 1975AcA....25..417D. 
  • Oshchepkov, V. A. (April 1974), "Polarimetric Observations of AW UMa", Information Bulletin on Variable Stars 884: 1, Bibcode: 1974IBVS..884....1O. 
  • Wilson, R. E.; Devinney, E. J. (June 1973), "Fundamental data for contact binaries: RZ Comae Berenices, RZ Tauri, and AW Ursae Majoris", Astrophysical Journal 182: 539, doi:10.1086/152162, Bibcode: 1973ApJ...182..539W. 
  • Kalish, Melvin S. (February 1965), "The Light Variation of the Eclipsing Binary BD +30°2163", Publications of the Astronomical Society of the Pacific 77 (454): 36, doi:10.1086/128148, Bibcode: 1965PASP...77...36K. 




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