Astronomy:BG Canis Minoris

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Short description: Variable star in the constellation of Canis Minor
BG Canis Minoris
BGCMiLightCurve.png
Light curves for BG Canis Minoris, adapted from McHardy et al. (1984)[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Canis Minor
Right ascension  07h 31m 29.008s[2]
Declination 09° 56′ 23.03″[2]
Apparent magnitude (V) 14.5[3] (14.7 to 15.2)[4]
Characteristics
Variable type Intermediate polar[1]
Astrometry
Proper motion (μ) RA: −13.616[2] mas/yr
Dec.: 3.347[2] mas/yr
Parallax (π)1.1199 ± 0.0334[2] mas
Distance2,910 ± 90 ly
(890 ± 30 pc)
Orbit[5]
Period (P)0.1349 d
Semi-major axis (a)1.09–1.33 R☉
Eccentricity (e)0.0
Periastron epoch (T)2,445,731.8184±12.0 HJD
Semi-amplitude (K1)
(primary)		75.00 km/s
Details
White dwarf
Mass0.78+0.08
−0.07[6] M☉
Donor star
Mass0.38[5] M☉
Other designations
3A 0729+103, BG CMi, 2MASS J07312900+0956231[7]
Database references
SIMBADdata

BG Canis Minoris is a binary star system in the equatorial constellation of Canis Minor, abbreviated BG CMi. With an apparent visual magnitude that fluctuates around 14.5,[3] it is much too faint to be visible to the naked eye. Parallax measurements provide a distance estimate of approximately 2,910 light years from the Sun.[2]

In 1981, I. M. McHardy and associates included the X-ray source '3A 0729+103' in their Ariel 5 satellite 3A catalogue.[8] The team used a localized search of those coordinates with the Einstein Observatory to isolate an X-ray source that matched the location of a blue-hued star with a visual magnitude of 14.5. The light curve for this star proved quite similar to other intermediate polars that had been identified as X-ray sources. The overall brightness variation of 3A 0729+103 matched a binary system with an orbital period of 194.1 minutes. It displays a more rapid variation with a period of 913 seconds, which was interpreted as related to a spin period.[1]

The standard model for this category of variable star consists of a magnetized white dwarf in a close orbit with a cool main sequence secondary star. The Roche lobe of the secondary is overflowing, and this stream of matter is falling onto an accretion disk in orbit around the primary. X-ray observations with the EXOSAT observatory in 1984–1985 demonstrated there are two regions of emission. One of these is believed to be at the magnetic poles of the white dwarf component, while the second is located where the accretion stream is striking the white dwarf's magnetosphere. The emission at the pole is partially eclipsed by the rotation of the white dwarf.[9]

In 1987, cyclotron radiation was discovered based on the circular polarization of its near infrared output, the first conclusive identification of this behavior for an intermediate polar. This emission confirmed the model of a magnetic white dwarf that is accreting mass.[10] Measurements suggested a magnetic field strength of 2 to 6 MG.[11] Changes in the rotation period over time indicate that the white dwarf is slowly being spun up due to torque from accreted matter.[3] It has an estimated 78%[6] of the mass of the Sun, while the donor companion has about 38%.[5]

References

  1. ↑ 1.0 1.1 1.2 McHardy, I. M. et al. (October 1984), "Identification of 3A 0729+103 with an intermediate polar-type cataclysmic variable", Monthly Notices of the Royal Astronomical Society 210 (3): 663–672, doi:10.1093/mnras/210.3.663, Bibcode: 1984MNRAS.210..663M. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 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 Augusteijn, T. et al. (July 1991), "Spin-up of the white dwarf in the intermediate polar BG Canis Majoris/3A0729+103", Astronomy and Astrophysics 247: 64, Bibcode: 1991A&A...247...64A. 
  4. ↑ 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. 
  5. ↑ 5.0 5.1 5.2 Penning, W. R. (February 1985), "Time-resolved spectroscopy of long-period DQ Herculis stars", Astrophysical Journal 289: 300–309, doi:10.1086/162889, Bibcode: 1985ApJ...289..300P. 
  6. ↑ 6.0 6.1 Shaw, A. W. et al. (November 2020), "Measuring the masses of magnetic white dwarfs: a NuSTAR legacy survey", Monthly Notices of the Royal Astronomical Society 498 (3): 3457–3469, doi:10.1093/mnras/staa2592, Bibcode: 2020MNRAS.498.3457S. 
  7. ↑ "BG CMi". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BG+CMi. 
  8. ↑ McHardy, I. M.; Lawrence, A.; Pye, J. P.; Pounds, K. A. (December 1981), "The Ariel V (3A) catalogue of X-ray sources. II", Monthly Notices of the Royal Astronomical Society 197: 893–919, doi:10.1093/mnras/197.4.893, Bibcode: 1981MNRAS.197..893M. 
  9. ↑ McHardy, I. M. et al. (March 1987), "Detailed EXOSAT and optical observations of the intermediate polar 3A0729+103 : discovery of two medium energy X-ray emission regions", Monthly Notices of the Royal Astronomical Society 225 (2): 355–368, doi:10.1093/mnras/225.2.355, Bibcode: 1987MNRAS.225..355M. 
  10. ↑ West, Steven C. et al. (November 1987), "The Discovery of Near-Infrared Polarized Cyclotron Emission in the Intermediate Polar BG Canis Minoris", The Astrophysical Journal 322: L35–L39, doi:10.1086/185032, Bibcode: 1987ApJ...322L..35W. 
  11. ↑ Chanmugam, G. et al. (February 1990), "The Magnetic Field of the Intermediate Polar BG Canis Minoris", Astrophysical Journal Letters 350: L13, doi:10.1086/185656, Bibcode: 1990ApJ...350L..13C. 

Further reading

  • Bonnardeau, Michel (May 2016), "BG CMi time keeping", Information Bulletin on Variable Stars 6168: 1, Bibcode: 2016IBVS.6168....1B. 
  • Choi, Chul-Sung et al. (November 2007), "The X-ray pulse profile of BG CMi", New Astronomy 12 (8): 622–629, doi:10.1016/j.newast.2007.05.002, Bibcode: 2007NewA...12..622C. 
  • Kim, Y. G. et al. (October 2005), "Orbital and spin variability of the intermediate polar BG CMi", Astronomy and Astrophysics 441 (2): 663–674, doi:10.1051/0004-6361:20052995, Bibcode: 2005A&A...441..663K. 
  • Andronov, I. L. et al. (July 2005), Sterken, C., ed., "O-C Analysis of the Intermediate Polar BG CMi", The Light-Time Effect in Astrophysics, Proceedings of ASP Conference Series, Vol. 335, held in Brussels 19–22 July 2004 (San Francisco: Astronomical Society of the Pacific) 335: p. 355, Bibcode: 2005ASPC..335..355A. 
  • Hellier, Coel (July 1997), "Spectroscopy of the intermediate polars BG Canis Minoris and PQ Geminorum", Monthly Notices of the Royal Astronomical Society 288 (4): 817–832, doi:10.1093/mnras/288.4.817, Bibcode: 1997MNRAS.288..817H. 
  • Pych, W. et al. (April 1996), "CCD Photometry of the Intermediate Polar BG Canis Minoris", Acta Astronomica 46: 279–285, Bibcode: 1996AcA....46..279P. 
  • Garlick, M. A. (1996), "Rotational Disturbance in BG CMi", Cataclysmic Variables and Related Objects, Astrophysics and Space Science Library 208: 179–180, doi:10.1007/978-94-009-0325-8_52, ISBN 978-94-010-6632-7, Bibcode: 1996ASSL..208..179G. 
  • de Martino, D. et al. (June 1995), "A photometric and spectroscopic study of BG Canis Minoris", Astronomy and Astrophysics 298: 849–862, Bibcode: 1995A&A...298..849D. 
  • Norton, A. J. et al. (October 1992), "BG Canis Minoris/3A 0729+103 : the true spin period revealed ?", Monthly Notices of the Royal Astronomical Society 258 (4): 697–704, doi:10.1093/mnras/258.4.697, Bibcode: 1992MNRAS.258..697N. 
  • Singh, Jyoti et al. (October 1991), "Spin-up of the White Dwarf in the Intermediate Polar 3A 0729+103", Astrophysical Journal 380: 208, doi:10.1086/170575, Bibcode: 1991ApJ...380..208S. 
  • Singh, J. et al. (1991), "Study of pulsations in the nova-like variable KR AUR and the intermediate polar BG CMi", IAU, Asian-Pacific Regional Astronomy Meeting, 5th, Sydney, Australia, July 16–20, 1990, Proceedings. A92-56476 24-90 (Astronomical Society of Australia, Proceedings (ISSN 0066-9997)) 9 (2): pp. 279, 280, doi:10.1017/S1323358000024139, Bibcode: 1991PASA....9..279S. 
  • Vaidya, J. et al. (October 1988), "Further fast photometric observations of intermediate polar 3A 0729+103", Astronomy and Astrophysics Supplement Series 75: 43–46, Bibcode: 1988A&AS...75...43V. 
  • Falomo, R. et al. (March 1987), "Optical and Ultraviolet Observations of the Intermediate Polar 3A:0729+103 - Modulation with the Orbital Period", Astrophysics and Space Science 131 (1–2): 631–635, doi:10.1007/BF00668148, Bibcode: 1987Ap&SS.131..631F. 
  • Penning, W. R. et al. (February 1986), "Circular Polarization in the DQ Herculis Binary 3A 0729+103", Astrophysical Journal 301: 881, doi:10.1086/163952, Bibcode: 1986ApJ...301..881P. 
  • Agrawal, P. C. et al. (February 1984), "Optical pulsations in the cataclysmic binary 3A 0729+103", Astronomy and Astrophysics 131: 192–195, Bibcode: 1984A&A...131..192A. 
  • McHardy, I. M. et al. (April 1982), Marsden, B. G., ed., "3A 0729+103", IAU Circular 3687: p. 1, Bibcode: 1982IAUC.3687....1M. 




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