Astronomy:OY Carinae

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Short description: Binary star in the constellation Carina
OY Carinae
250px
A blue band light curve for OY Carinae, adapted from Khruzina1 et al. (2003).[1] The main plot shows the full light curve, and the inset shows the minimum with an expanded horizontal scale.
Observation data
Equinox J2000.0]] (ICRS)
Constellation Carina
Right ascension  10h 06m 22.079s[2]
Declination −70° 14′ 04.58″
Apparent magnitude (V) Max: 11.9
Min: 18.2[3]
Characteristics
Spectral type DA + M8–9V[4]
Variable type SU UMa+Algol[3]
Astrometry
Radial velocity (Rv)120[5] km/s
Proper motion (μ) RA: –38.830[2] mas/yr
Dec.: 7.286[2] mas/yr
Parallax (π)11.039 ± 0.0254[2] mas
Distance295.5 ± 0.7 ly
(90.6 ± 0.2 pc)
Orbit
Period (P)0.000172 yr
Semi-major axis (a)0.00213 AU
Eccentricity (e)0.0
Inclination (i)83.3°
Orbit[6]
Period (P)0.0631209247 d
Semi-major axis (a)0.43 ± 0.03 Gm (0.00287 ± 0.00020 AU)
Inclination (i)79±2°
Semi-amplitude (K2)
(secondary)		470.0±2.7[4] km/s
Details
Primary
Mass≈0.7[7] M☉
Radius0.011[7] R☉
Luminosity0.0055 L☉
Temperature15,000±2,000[8] K
Secondary
Mass0.07[9] M☉
Radius0.127[9] R☉
Luminosity0.00117 L☉
Temperature3,000 K
Rotational velocity (v sin i)108±6[4] km/s
Other designations
2MASS J10062206-7014045[10]
Database references
SIMBADdata

OY Carinae is an eclipsing binary star system in the southern constellation of Carina, abbreviated OY Car. It is located at a distance of approximately 296 light-years from the Sun, and is classed as a cataclysmic variable. The system comprises a double eclipsing white dwarf and red dwarf that orbit each other every 1.51 hours, and possibly a yet unconfirmed third low-mass (substellar?) companion.

Observations

Cuno Hoffmeister discovered that the star is a cataclysmic variable, in 1959.[11] In 1976, it was identified as a candidate SU Ursae Majoris (SU UMa)-type variable.[12] It was found to be a double eclipsing binary system by Nikolaus Vogt in 1979, who determined a period of 91 minutes.[13] This behavior potentially allows for precise determination of the physical parameters of the system.[6] Superhumps during an outburst of OY Car were reported in 1980, confirming its status as an SU UMa variable.[14]

The standard model for this type of system has a cool star orbiting a compact white dwarf. The cool star is filling its Roche lobe and is feeding matter to an accretion disk orbiting the white dwarf. The eclipsing of the accretion disk allows its dimensions to be estimated.[15] The impact point of the material contacting the accretion disk produces a "hot spot", which is responsible for the superhump feature in the light curve.[8]

By 1991, superoutbursts of OY Car were found to occur on an almost annual cycle, with a mean time interval of 346.5 days. However, individual cycles could range from 354 to 472 days. The mean maximum magnitude was 11.45, with the system being above magnitude 13 for an average of 12 days.[16] These superoutbursts are thought to occur during periods of rapid accretion onto the white dwarf, which in SU UMa systems can be triggered by tidal resonances in the disk.[17] During a superoutburst, the temperature of the white dwarf can increase to 19,700 K before steadily declining.[18]

As material accretes onto the white dwarf it undergoes decelaration and emits X-rays. However, the high inclination of the system means that this emission is obscured by the disk.[17][19] Most of the X-ray emission from OY Car appear to come from the polar regions.[20] This suggests the accretion is magnetically directed onto the pole of an inclined dipolar field.[21]

Planetary system?

Greenhill et al. (2009) would invoke the presence of a third object to explain orbital period variations with an apparent periodicity of roughly 35 years. The third body could yield a minimum mass 7 times greater than Jupiter and be located 9.5 astronomical units away from the cataclysmic variable system,[22] being likely either a massive planetary object or else a very low-mass brown dwarf.

It is likely that the apparent change is due to solar cycle type magnetic activity in the secondary star. Large irregular deviations from the general trend, with time-scales of years, also occur. Further observations will be able to confirm or disprove the presence of a substellar companion.

Diagram of the probable structure of the OY Carinae Star System.
The OY Carinae planetary system[22]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination Radius
b (unconfirmed) ≥7 MJ 9.5 35±3.5 — — —

See also

References

  1. ↑ Khruzina, T. S. et al. (March 2003). "Interpretation of Light Curves of the Cataclysmic Variable OY Car in a Model with Shockless Interaction between a Gaseous Stream and the Disk". Astronomy Reports 47 (3): 214–231. doi:10.1134/1.1562216. Bibcode: 2003ARep...47..214K. 
  2. ↑ 2.0 2.1 2.2 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.
  3. ↑ 3.0 3.1 N. N., Samus et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. GCVS 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S. http://www.sai.msu.su/gcvs/gcvs/. Retrieved 2025-03-18. 
  4. ↑ 4.0 4.1 4.2 Copperwheat, C. M. et al. (March 2012). "A J-band detection of the donor star in the dwarf nova OY Carinae and an optical detection of its 'iron curtain'". Monthly Notices of the Royal Astronomical Society 421 (1): 149–158. doi:10.1111/j.1365-2966.2011.20282.x. Bibcode: 2012MNRAS.421..149C. 
  5. ↑ Duflot, M. et al. (1995). "Vitesses radiales. Catalogue WEB: Wilson Evans Batten (Radial velocities: The Wilson-Evans-Batten catalogue)". Astronomy and Astrophysics Supplement Series 114: 269. Bibcode: 1995A&AS..114..269D. 
  6. ↑ 6.0 6.1 Vogt, N. et al. (February 1981). "The eclipsing dwarf nova OY CAR : ephemeris and physical parameters". Astronomy and Astrophysics 94: L29–L32. Bibcode: 1981A&A....94L..29V. 
  7. ↑ 7.0 7.1 Mauche, C. W.; Raymond, J. C. (2000). "The EUV Emission-Line spectrum of OY Carinae in superoutburst: scattering in the wind". in Arthur, Jane; Brickhouse, Nancy; Franco, José. Astrophysical Plasmas: Codes, Models, and Observations, Proceedings of the conference held in Mexico City, October 25-29, 1999. 9. 232–233. Bibcode: 2000RMxAC...9..232M. 
  8. ↑ 8.0 8.1 8.2 Hessman, F. V. et al. (April 1989). "Time-resolved spectroscopy of the eclipsing dwarf nova OY Carinae". Astronomy and Astrophysics 213: 167–175. Bibcode: 1989A&A...213..167H. 
  9. ↑ 9.0 9.1 Wood, Janet H. et al. (1989). "Eclipse studies of the dwarf nova OY Carinae in quiescence". Astrophysical Journal 341: 974–994. doi:10.1086/167557. Bibcode: 1989ApJ...341..974W. 
  10. ↑ "OY Car". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=OY+Car. 
  11. ↑ Vogt, N.; Schoembs, R.; Krzeminski, W.; Pedersen, H (February 1981). "The eclipsing dwarf nova OY CAR : ephemeris and physical parameters". Astronomy and Astrophysics 94: L29–L32. Bibcode: 1981A&A....94L..29V. 
  12. ↑ Vogt, N. (August 1980). "The SU UMa stars, an important sub-group of dwarf novae". Astronomy and Astrophysics 88: 66–76. Bibcode: 1980A&A....88...66V. 
  13. ↑ Vogt, N. (June 1979). "Discovery of a new eclipsing dwarf nova: OY Carinae". The Messenger 17: 39–40. Bibcode: 1979Msngr..17...39V. 
  14. ↑ Bailey, J.; Ward, M. (January 1981). "Spectrophotometry of the eclipsing dwarf nova OY Car.". Monthly Notices of the Royal Astronomical Society 194: 17P–23P. doi:10.1093/mnras/194.1.17P. Bibcode: 1981MNRAS.194P..17B. 
  15. ↑ Wlodarczyk, K. (January 1989). "The accretion disc in OY CAR during rise to outburst". Communications of the Konkoly Observatory 10 (93): 235. Bibcode: 1989CoKon..93..235W. 
  16. ↑ Bateson, F. M. et al. (1991). "The superoutbursts cycle of OY Carinae". Royal Astronomical Society of New Zealand - Publications of Variable Star Section 17: 83–84. Bibcode: 1991PVSS...17...83B. 
  17. ↑ 17.0 17.1 Pratt, Gabriel W. et al. (November 1999). "Optical and ROSAT X-ray observations of the dwarf nova OY Carinae in superoutburst and quiescence". Monthly Notices of the Royal Astronomical Society 309 (4): 847–861. doi:10.1046/j.1365-8711.1999.02900.x. Bibcode: 1999MNRAS.309..847P. 
  18. ↑ Cheng, F. H. et al. (October 2000). "Temporal Variations of the White Dwarf and Disk in OY Carinae Following the 1992 Superoutburst". The Astrophysical Journal 542 (2): 1064–1070. doi:10.1086/317012. Bibcode: 2000ApJ...542.1064C. 
  19. ↑ Pratt, Gabriel W. et al. (August 1999). "An eclipse of the X-ray flux from the dwarf nova OY Carinae in quiescence". Monthly Notices of the Royal Astronomical Society 307 (2): 413–419. doi:10.1046/j.1365-8711.1999.02601.x. Bibcode: 1999MNRAS.307..413P. 
  20. ↑ Wheatley, Peter J.; West, Richard G. (November 2003). "The X-ray eclipse of OY Car resolved with XMM-Newton: X-ray emission from the polar regions of the white dwarf". Monthly Notices of the Royal Astronomical Society 345 (3): 1009–1014. doi:10.1046/j.1365-8711.2003.07030.x. Bibcode: 2003MNRAS.345.1009W. 
  21. ↑ 21.0 21.1 Woudt, Patrick A.; Warner, Brian (December 2009). "Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - VII. OY Carinae and oscillations in dwarf novae in quiescence". Monthly Notices of the Royal Astronomical Society 400 (2): 835–842. doi:10.1111/j.1365-2966.2009.15488.x. Bibcode: 2009MNRAS.400..835W. 
  22. ↑ 22.0 22.1 Greenhill; Hill, K. M.; Dieters, S.; Fienberg, K. et al. (2006). "Decrease in the orbital period of dwarf nova OY Carinae". Monthly Notices of the Royal Astronomical Society 372 (3): 1129–1132. doi:10.1111/j.1365-2966.2006.10920.x. Bibcode: 2006MNRAS.372.1129G. 

Further reading

  • Pilarčík, L. et al. (April 2018). "Period changes of cataclysmic variables below the period gap: V2051 Oph, OY Car and Z Cha". New Astronomy 60: 1–6. doi:10.1016/j.newast.2017.09.005. Bibcode: 2018NewA...60....1P. 
  • Han, Z. -T. et al. (January 2015). "An orbital period analysis of the dwarf novae OY Carinae". New Astronomy 34: 1–5. doi:10.1016/j.newast.2014.04.011. Bibcode: 2015NewA...34....1H. 
  • Smak, J. (June 2012). "Stream Overflow in Z Cha and OY Car during Quiescence". Acta Astronomica 62 (2): 213–217. Bibcode: 2012AcA....62..213S. 
  • Nicholson, M. (June 2009). "Eclipses of OY Carinae in outburst". The Journal of the American Association of Variable Star Observers 37 (1): 40. Bibcode: 2009JAVSO..37...40N. 
  • Smak, J. (March 2008). "The hot spot in OY Car during its superoutburst". Acta Astronomica 58: 65–67. Bibcode: 2008AcA....58...65S. 
  • Hakala, P.; Ramsay, G. (March 2004). "XMM-Newton observations of OY Car III: OM light curve modelling, X-ray timing and spectral studies". Astronomy and Astrophysics 416 (3): 1047–1055. doi:10.1051/0004-6361:20034059. Bibcode: 2004A&A...416.1047H. 
  • Khruzina, T. S. et al. (March 2003). "Interpretation of Light Curves of the Cataclysmic Variable OY Car in a Model with Shockless Interaction between a Gaseous Stream and the Disk". Astronomy Reports 47 (3): 214–231. doi:10.1134/1.1562216. Bibcode: 2003ARep...47..214K. 
  • Wheatley, P. J.; West, R. G. (January 2002). "Further analysis of the X-ray eclipse of OY Car measured with XMM-Newton". in Gänsicke, B. T.; Beuermann, K.; Reinsch, K.. The Physics of Cataclysmic Variables and Related Objects. 261. San Francisco: Astronomical Society of the Pacific. p. 433. ISBN 1-58381-101-X. Bibcode: 2002ASPC..261..433W. 
  • Ramsay, G. et al. (January 2001). "First XMM-Newton observations of a cataclysmic variable I: Timing studies of OY Car". Astronomy and Astrophysics 365: L288–L293. doi:10.1051/0004-6361:20000039. Bibcode: 2001A&A...365L.288R. 
  • Ramsay, G. et al. (January 2001). "First XMM-Newton observations of a cataclysmic variable II: The X-ray spectrum of OY Car". Astronomy and Astrophysics 365: L294–L297. doi:10.1051/0004-6361:20000042. Bibcode: 2001A&A...365L.294R. 
  • Mauche, Christopher W.; Raymond, John C. (October 2000). "Extreme Ultraviolet Explorer Observations of OY Carinae in Superoutburst". The Astrophysical Journal 541 (2): 924–936. doi:10.1086/309489. Bibcode: 2000ApJ...541..924M. 
  • Mauche, C. W.; Raymond, J. C. (May 2000). "The EUV Emission-Line Spectrum of OY Carinae in Superoutburst: Scattering in the Wind". in Arthur, Jane; Brickhouse, Nancy; Franco, José. Astrophysical Plasmas: Codes, Models, and Observations, Proceedings of the conference held in Mexico City, October 25-29, 1999. 9. pp. 232–233. Bibcode: 2000RMxAC...9..232M. 
  • Marsh, T. R.; Horne, Keith (September 1998). "A double-frequency dwarf nova oscillation in OY CAR". Monthly Notices of the Royal Astronomical Society 299 (3): 921–928. doi:10.1046/j.1365-8711.1998.01852.x. Bibcode: 1998MNRAS.299..921M. 
  • Djurašević, Gojko (September 1996). "A model of light-curve synthesizing for dwarf novae and the analysis of the OY CAR observations by application of the inverse-problem method". Astrophysics and Space Science 240 (2): 317–329. doi:10.1007/BF00639595. Bibcode: 1996Ap&SS.240..317D. 
  • Harlaftis, E. T.; Marsh, T. R. (April 1996). "OY Carinae in outburst: Balmer emission from the red star and the gas stream". Astronomy and Astrophysics 308: 97–106. Bibcode: 1996A&A...308...97H. 
  • Billington, I. et al. (April 1996). "Superhumps and ultraviolet superdips: HST observations of OY Car". Monthly Notices of the Royal Astronomical Society 279 (4): 1274–1288. doi:10.1093/mnras/279.4.1274. Bibcode: 1996MNRAS.279.1274B. 
  • Bruch, A. et al. (February 1996). "Multicolor photometry and eclipse mapping of OY Carinae in a superoutburst.". Astronomy and Astrophysics 306: 151. Bibcode: 1996A&A...306..151B. 
  • Horne, Keith et al. (May 1994). "HST eclipse mapping of dwarf nova OY Carinae in quiescence: an 'Fe II curtain' with Mach 6 velocity dispersion veils the white dwarf". Astrophysical Journal 426: 294. doi:10.1086/174064. Bibcode: 1994ApJ...426..294H. 
  • Cheng, F. H.; Marsh, T. R.; Horne, K.; Hubeny, I. (January 1994). "The cooling of the white dwarf in OY CAR after 1992 superoutburst". in Holt, Steve; Day, Charles S.. The Evolution of X-ray Binaries, Proceedings of a conference held in College Park, MD, 1993. 308. New York: American Institute of Physics Press. p. 197. doi:10.1063/1.46008. Bibcode: 1994AIPC..308..197C. 
  • Beele, D. et al. (1994). "Eclipse mapping of the dwarf nova OY Carinae in superoutburst". Astronomische Gesellschaft Abstract Series 10: 70. Bibcode: 1994AGAb...10...70B. 
  • Rutten, R. G. M. et al. (November 1992). "OY Carinae revisited: development of the accretion disk during a normal outburst". Astronomy and Astrophysics 265: 159–167. Bibcode: 1992A&A...265..159R. 
  • Hessman, F. V. et al. (September 1992). "OY Carinae: the secrets of the super-humps revealed". Astronomy and Astrophysics 263: 147–160. Bibcode: 1992A&A...263..147H. 
  • Wood, Janet H. (March 1990). "Can the quiescent accretion discs in the dwarf novae OY CAR and Z Chabe in a steady state ?". Monthly Notices of the Royal Astronomical Society 243: 219–230. Bibcode: 1990MNRAS.243..219W. 
  • Wood, Janet H. et al. (June 1989). "Eclipse Studies of the Dwarf Nova OY Carinae in Quiescence". Astrophysical Journal 341: 974. doi:10.1086/167557. Bibcode: 1989ApJ...341..974W. 
  • Naylor, T. et al. (March 1988). "The 1985 May superoutburst of the dwarf nova OY Carinae - II. IUE andEXOSAT observations". Monthly Notices of the Royal Astronomical Society 231 (2): 237–255. doi:10.1093/mnras/231.2.237. Bibcode: 1988MNRAS.231..237N. 
  • Schoembs, R. et al. (July 1987). "Simultaneous multicolour photometry of OY Carinae during quiescence". Astronomy and Astrophysics 181: 50–56. Bibcode: 1987A&A...181...50S. 
  • Naylor, T. et al. (February 1987). "The May 1985 super outburst of OY-Carinae - Part One - Structure of the outer disk from optical and infrared observations". Astrophysics and Space Science 130 (1–2): 365–369. doi:10.1007/BF00655018. Bibcode: 1987Ap&SS.130..365N. 
  • Ritter, H. (May 1980). "The physical parameters of the dwarf nova OY Car". Astronomy and Astrophysics 85: 362–364. Bibcode: 1980A&A....85..362R. 

Coordinates: Sky map 10h 06m 22.07s, −70° 14′ 04.6″



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