SW Ursae Majoris

Variable star in the constellation Ursa Major
SW Ursae Majoris

Light curves for SW Ursae Majoris, adapted from Robinson et al. (1987)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 08h 36m 42.749s[2]
Declination +53° 28′ 37.98″[2]
Apparent magnitude (V) 9.7 to 16.5[3]
Characteristics
Variable type U Gem[3]
Astrometry
Proper motion (μ) RA: −28.713 mas/yr[2]
Dec.: 5.928 mas/yr[2]
Parallax (π)6.2002 ± 0.0602 mas[2]
Distance526 ± 5 ly
(161 ± 2 pc)
Absolute magnitude (MV)+4.9 (at maximum)[4]
Details
White dwarf
Mass0.61+0.06
−0.04[5] M☉
Radius0.0129+0.0009
−0.0010[5] R☉
Surface gravity (log g)8.01+0.11
−0.09[5] cgs
Temperature13,854+189
−131[5] K
donor
Mass0.1[6] M☉
Luminosity0.001[6] L☉
Other designations
SW UMa, 2MASS J08364276+5328378[7]
Database references
SIMBADdata

SW Ursae Majoris is a cataclysmic binary star system in the northern circumpolar constellation of Ursa Major, abbreviated SW UMa. During quiescence it has an apparent visual magnitude of 16.5–17, which is too faint to be visible to the naked eye.[8] Based on parallax measurements, it is located at a distance of approximately 526 light years from the Sun.[2]

The variable nature of this object was noted by L. Tseraskaya in 1909 when it increased in brightness to 10th magnitude.[9][10] It was determined to be a U Geminorum star, indicating this is a binary star system.[11] A short orbital period of 81.8 minutes was determined by A. W. Shafter and associates in 1986.[12] The same year, E. L. Robinson and associates detected superhumps with a period of 84.0 minutes.[1] Large amplitude quasi-periodic oscillations were observed by T. Kato and associates in 1992, which is a property of SU UMa-type dwarf novae.[13]

When the system is in a quiet period, it displays a periodicity of 15.9 minutes and has a marginal emission of soft X-rays. This is likely the rotation period of the white dwarf, and the system resembles an intermediate polar with a strongly-magnetized white dwarf as the accreting component.[8] It undergoes outbursts that vary in brightness and duration.[14] During quiescence, it is estimated that about 70% of the bolometric luminosity of the system is produced by the white dwarf, with almost all the rest produced by the accretion disk.[15]

References

  1. ^ a b Robinson, Edward L.; et al. (February 1987), "Detection of Superhumps and Quasi-periodic Oscillations in the Light Curve of the Dwarf Nova SW Ursae Majoris", Astrophysical Journal, 313: 772, Bibcode:1987ApJ...313..772R, doi:10.1086/165015.
  2. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  3. ^ a b Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  4. ^ Patterson, Joseph (2011), "Distances and absolute magnitudes of dwarf novae: Murmurs of period bounce", Monthly Notices of the Royal Astronomical Society, 411 (4): 2695–2716, arXiv:0903.1006, Bibcode:2011MNRAS.411.2695P, doi:10.1111/j.1365-2966.2010.17881.x.
  5. ^ a b c d Pala, A. F.; et al. (March 2022), "Constraining the evolution of cataclysmic variables via the masses and accretion rates of their underlying white dwarfs", Monthly Notices of the Royal Astronomical Society, 510 (4): 6110–6132, arXiv:2111.13706, Bibcode:2022MNRAS.510.6110P, doi:10.1093/mnras/stab3449.
  6. ^ a b Povich, M. S.; et al. (September 24, 2004), "Far Ultraviolet Spectroscopic Explorer Observations of the Dwarf Nova SW Ursae Majoris during Quiescence", arXiv, vol. 617, no. 1, pp. 500–507, arXiv:astro-ph/0409588, Bibcode:2004ApJ...617..500P, doi:10.1086/425213, S2CID 31384959.
  7. ^ "SW UMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-09-12.
  8. ^ a b Soejima, Yuichi; et al. (August 2009), "Photometry of Three Superoutbursts of the SU UMa-Type Dwarf Nova, SW Ursae Majoris", Publications of the Astronomical Society of Japan, 61 (4): 659–674, arXiv:0905.0348, Bibcode:2009PASJ...61..659S, doi:10.1093/pasj/61.4.659.
  9. ^ Ceraski, W. (December 1909), "Note sur un astre qui est probablement une étoile variable (44.1909 Ursae majoris)", Astronomische Nachrichten (in French), 183 (7): 109, Bibcode:1909AN....183..109C, doi:10.1002/asna.19091830705.
  10. ^ Hornby, P. W. (October 1975), "Two U Geminorum variables: UV Per 1926–69 and SW UMa 1963–69", Journal of the British Astronomical Association, 85: 528–531, Bibcode:1975JBAA...85..528H.
  11. ^ Wellmann, P. (1952), "Lichtkurve und Maximumspektrum des U Geminorum-Veränderlichen SW Ursae maioris. Mit 7 Textabbildungen", Zeitschrift für Astrophysik (in German), 31: 123, Bibcode:1952ZA.....31..123W.
  12. ^ Shafter, A. W.; et al. (September 1986), "X-Ray and Optical Observations of the Ultrashort Period Dwarf Nova SW Ursae Majoris: A Likely New DQ Herculis Star", Astrophysical Journal, 308: 765, Bibcode:1986ApJ...308..765S, doi:10.1086/164549.
  13. ^ Kato, Taichi; et al. (October 1992), "Discovery of "Super-Quasi-Periodic Oscillations" during Superoutburst of Dwarf Nova SW Ursae Majoris", Publications of the Astronomical Society of Japan, 44: L215–L219, Bibcode:1992PASJ...44L.215K.
  14. ^ Howell, Steve B.; et al. (November 1995), "Ultraviolet Observations of SW Ursae Majoris, BC Ursae Majoris, and TV Corvi (1217--18): IUE Spectroscopy and Outburst Light Curves", Astrophysical Journal, 453: 454, Bibcode:1995ApJ...453..454H, doi:10.1086/176407.
  15. ^ Urban, Joel A; Sion, Edward M (2006). "The Dwarf Novae during Quiescence". The Astrophysical Journal. 642 (2): 1029–1041. arXiv:astro-ph/0602126. Bibcode:2006ApJ...642.1029U. doi:10.1086/501430. S2CID 1434460.

Further reading

  • Perez-Garcia, I.; et al. (October 2021), "Observations with the BOOTES Network of the current outburst in the dwarf-nova SW UMa", The Astronomer's Telegram, 14960: 1, Bibcode:2021ATel14960....1P.
  • İkis Gün, G.; et al. (December 2013), "Preliminary results of the spectral analysis of Suzaku data of SW Ursae Majoris and BZ Ursae Majoris", New Astronomy, 25: 1–6, Bibcode:2013NewA...25....1I, doi:10.1016/j.newast.2013.03.011.
  • Waagen, E. O.; et al. (September 2006), Green, D. W. E. (ed.), "SW Ursae Majoris", IAU Circular, vol. 8748, p. 2, Bibcode:2006IAUC.8748....2W.
  • Povich, M. S.; et al. (December 2004), "Far Ultraviolet Spectroscopic Explorer Observations of the Dwarf Nova SW Ursae Majoris during Quiescence", The Astrophysical Journal, 617 (1): 500–507, arXiv:astro-ph/0409588, Bibcode:2004ApJ...617..500P, doi:10.1086/425213, S2CID 31384959.
  • Burleigh, M. R.; et al. (August 2001), "A ROSAT WFC observation of SW UMa: the EUV behaviour of dwarf novae in superoutburst explained", Monthly Notices of the Royal Astronomical Society, 325 (4): 1458–1462, arXiv:astro-ph/0104010, Bibcode:2001MNRAS.325.1458B, doi:10.1046/j.1365-8711.2001.04551.x, S2CID 12041296.
  • Pavlenko, E. P.; et al. (October 2000), "CCD Photometry of the Cataclysmic Variable SW Ursae Majoris at a Late Stage of the 2000 Superoutburst", Astrophysics (English translation of Astrofizika), vol. 43, no. 4, pp. 419–429, Bibcode:2000Ap.....43..419P, doi:10.1023/A:1010914924206, S2CID 117641368.
  • Mattei, J. A.; et al. (February 2000), Green, D. W. E. (ed.), "SW Ursae Majoris", IAU Circular, vol. 7365, p. 2, Bibcode:2000IAUC.7365....2M.
  • Gänsicke, B. T.; Koester, D. (June 1999), "SW Ursae Majoris, CU Velorum and AH Mensae: three more accreting white dwarfs unveiled?", Astronomy and Astrophysics, 346: 151–157, Bibcode:1999A&A...346..151G.
  • Nogami, Daisaku; et al. (April 1998), "CCD Photometry of SW Ursae Majoris during the 1996 Superoutburst", Publications of the Astronomical Society of Japan, 50 (2): 297–302, Bibcode:1998PASJ...50..297N, doi:10.1093/pasj/50.2.297.
  • Mobberley, M. P.; et al. (April 1997), "C. R. d'Esterre and the mysteries of UV and UW Per", Journal of the British Astronomical Association, 107 (2): 65–71, Bibcode:1997JBAA..107...65M.
  • Semeniuk, I.; et al. (January 1997), "CCD Photometry of SW Ursae Majoris during the 1996 Superoutburst", Acta Astronomica, 47: 201–209, arXiv:astro-ph/9704215, Bibcode:1997AcA....47..201S.
  • Rosen, S. R.; et al. (August 1994), "ROSAT constraints on the intermediate polar candidates V426 Oph, SW UMa and 1H 0709-360." (PDF), Monthly Notices of the Royal Astronomical Society, 269 (4): 913–920, Bibcode:1994MNRAS.269..913R, doi:10.1093/mnras/269.4.913.
  • Szkody, Paula; et al. (May 1988), "EXOSAT and IUE Observations of SW UMa during Superoutburst", Astrophysical Journal, 328: 243, Bibcode:1988ApJ...328..243S, doi:10.1086/166286.
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