DO Draconis/YY Draconis

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DO Draconis/YY Draconis
DODraLightCurve.png
Light curves for DO Draconis. The upper plot, adapted from Andronov et al., [1] shows the long-term variability and eruptive behaviour. The lower plot, adapted from Hill et al., [2] shows the ellipsoidal variability assuming a period of 3.96898 hours.
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Draco
Right ascension 11h 43m 38.492s [3]
Declination +71° 41′ 20.56″ [3]
Apparent magnitude  (V)10.0 to 15.1 [4]
Characteristics
Spectral type + dM4 [5]
Variable type U Gem [4]
Astrometry
Proper motion (μ)RA: 14.379  mas/yr [3]
Dec.: 12.772  mas/yr [3]
Parallax (π)5.1049 ± 0.0278  mas [3]
Distance 639 ± 3  ly
(196 ± 1  pc)
Orbit
Period (P)3.968982 h [6]
Semi-major axis (a)1.35±0.15  R☉ [5]
Inclination (i)41±3 [6] °
Semi-amplitude (K1)
(primary)		87±13 [5] km/s
Semi-amplitude (K2)
(secondary)		184±10 [5] km/s
Details
Accreting white dwarf
Mass 0.83±0.10 [7]   M☉
Temperature 21,500 [8]   K
Rotation 529.31±0.02 s [7]
Donor red dwarf
Mass 0.375±0.014 [7]   M☉
Radius 0.42±0.08 [5]   R☉
Rotational velocity (v sin i)86±15 [5]  km/s
Other designations
DO Dra or YY Dra, 3A 1148+719, PG 1140+719, AAVSO 1137+72 [9]
Database references
SIMBAD data

YY Draconis and DO Draconis are separate identifiers for what is likely the same cataclysmic variable system in the northern constellation of Draco, abbreviated YY Dra and DO Dra, respectively. The DO Dra binary star system is classified as a U Geminorum variable that ranges in luminosity from an apparent visual magnitude of 10.0 down to 15.1. [4] It is located at a distance of approximately 639  light years from the Sun. [3]

Contents

Identification

The variable YY Draconis was identified by W. Tsesevich in 1934 and determined to be an Algol type binary that ranged in brightness from apparent magnitude 12.9 to under 14.5 with a period of 4.21123 days. However, subsequent scans of photographic plates at the same coordinates have failed to identify any such variation. Hence, a positional reporting error is suspected, [10] and no further observations of this variable were reported (as of 1983). [11]

In 1982, the X-ray emission source PG 1148+719 (3A 1148+719) was associated with a star displaying the spectrum of a U Geminorum variable by R. F. Green and associates. In their paper, they identified this star as YY Dra, based on a positional search of the General Catalogue of Variable Stars . [12] The following year, W. Wenzel found the association with YY Dra appeared erroneous but discovered a nearby eruptive variable that brightened to magnitude 10.6 then dimmed to below magnitude 14.5. He estimated a lengthy cycle time of 5 to 20 years, comparable to BZ Ursae Majoris. [11] This cataclysmic variable was cataloged as DO Draconis.

An outburst of DO Dra was observed while in progress in 1985, which brought the system to about a magnitude brighter than minimum. [13] [14] In 1987, a debate arose as to whether this is the same variable as YY Dra, as the coordinates are separated by only 53″. [10] [15] Discussion of this identity conflict has continued as recently as 2022, and, historically, both identifiers have been used to discuss the same cataclysmic variable. A full resolution of this conflict may prove impossible since many of the original photographic plates were destroyed during World War II. The continued use of DO Dra for this variable has been encouraged since it is an unambiguous identifier. [16]

Properties

In 1991, M. Mateo and associates found an orbital period of 3.96 h with a semimajor axis of 1.35±0.15  R☉ for this binary system. DO Dra consists of a compact white dwarf primary being orbited by a red dwarf stellar companion. The red dwarf has filled its Roche lobe and is losing mass, which is being accreted by the white dwarf. Because of the close orbit, the red dwarf is rotating rapidly and is expected to be magnetically active. However, the majority of the ionized calcium emission lines originate from irradiation of the red dwarf by soft X-rays coming from the primary. [5]

This system was identified as a DQ Herculis variable by J. Patterson and associates in 1994 – also known as an intermediate polar. This indicates the white dwarf has a sufficiently strong magnetic field to channel the flow of gas from an orbiting accretion disk onto its magnetic poles. The shock from this accretion is producing the X-ray flux. [17] A 1997 study based on observations with the Hubble Space Telescope found a rotation period of 529.31±0.02 s for the white dwarf. This spin rate is producing coherent pulsations that are detectable in both the visual and X-ray spectrum. [7] The magnetic poles reach effective temperatures of 220,000 K in the accretion region, compared to 21,500 K for the remainder of the white dwarf surface. [8]

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References

  1. ↑ Andronov, I. L.; Chinarova, L. L.; Han, W.; Kim, Y.; Yoon, J. N. (August 2008). "Multiple timescales in cataclysmic binaries. The low-field magnetic dwarf nova DO Draconis" (PDF). Astronomy and Astrophysics. 486 (3): 855–865. arXiv: 0806.1995 . Bibcode:2008A&A...486..855A. doi:10.1051/0004-6361:20079056. S2CID   18374995 . Retrieved 26 May 2023.
  2. ↑ Hill, Katherine L.; Littlefield, Colin; Garnavich, Peter; Scaringi, Simone; Szkody, Paula; Mason, Paul A.; Kennedy, Mark R.; Shaw, Aarran W.; Covington, Ava E. (June 2022). "Hitting a New Low: The Unique 28 hr Cessation of Accretion in the TESS Light Curve of YY Dra (DO Dra)". The Astronomical Journal. 163 (6): 246. arXiv: 2203.00221 . Bibcode:2022AJ....163..246H. doi: 10.3847/1538-3881/ac5a51 . S2CID   247187776.
  3. 1 2 3 4 5 6 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.
  4. 1 2 3 Samus', N. N; et al. (2017), "General catalogue of variable stars", Astronomy Reports, GCVS 5.1, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID   125853869.
  5. 1 2 3 4 5 6 7 Mateo, Mario; et al. (March 1991), "Near-Infrared Time-resolved Spectroscopy of the Cataclysmic Variable YY Draconis", Astrophysical Journal, 370: 370, Bibcode:1991ApJ...370..370M, doi:10.1086/169823.
  6. 1 2 Joshi, Vishal (2013), Khare, Pushpa; Ishwara-Chandra, C. H. (eds.), "Near-infrared photometric study of intermediate polar YY Draconis", 31st ASI Meeting, ASI Conference Series, vol. 9, p. 80, Bibcode:2013ASInC...9...80J.
  7. 1 2 3 4 Haswell, Carole A.; et al. (February 1997), "Pulsations and Accretion Geometry in YY Draconis: A Study Based on Hubble Space Telescope Observations", The Astrophysical Journal, 476 (2): 847–864, Bibcode:1997ApJ...476..847H, doi:10.1086/303630, S2CID   121217299.
  8. 1 2 Hoard, D. W.; Linnell, A. P.; Szkody, Paula; Sion, Edward M. (July 2005), "Spin-resolved Far-Ultraviolet Observations of the Magnetic White Dwarf in YY Draconis", The Astronomical Journal, 130 (1): 214–223, Bibcode:2005AJ....130..214H, doi: 10.1086/430749 , S2CID   121358198.
  9. ↑ "DO Dra", SIMBAD , Centre de données astronomiques de Strasbourg , retrieved 2022-05-16.
  10. 1 2 Patterson, J.; Eisenman, N. (August 1987), "Let's Forget DO Dra", Information Bulletin on Variable Stars, 3079: 1, Bibcode:1987IBVS.3079....1P.
  11. 1 2 Wenzel, W. (January 1983), "The X-Ray Source 3A1148+719 is another Dwarf Nova with Very Long Cycle Length", Information Bulletin on Variable Stars, 2262: 1, Bibcode:1983IBVS.2262....1W.
  12. ↑ Green, R. F.; et al. (June 1982), "Cataclysmic variable candidates from the Palomar Green Survey", Publications of the Astronomical Society of the Pacific, 94: 560-564, Bibcode:1982PASP...94..560G, doi:10.1086/131022, S2CID   120644760.
  13. ↑ McNaught, R. H.; et al. (November 1985), Green, D. W. E. (ed.), "DO Draconis", IAU Circular, 4143: 2, Bibcode:1985IAUC.4143....2M.
  14. ↑ Hurst, G. M.; et al. (November 1985), Marsden, B. G. (ed.), "DO Draconis", IAU Circular, 4130: 1, Bibcode:1985IAUC.4130....1H.
  15. ↑ Kholopov, P. N.; Samus, N. N. (March 1988), "Should we Really Forget DO Dra?", Information Bulletin on Variable Stars, 3154: 1, Bibcode:1988IBVS.3154....1K.
  16. ↑ Kato, Taichi; Pavlenko, Elena P. (March 2022), "On the identity of Tsesevich's "YY Dra"", arXiv: 2203.05091 [astro-ph.SR]
  17. ↑ Patterson, J.; et al. (June 1992), "Rapid Oscillations in Cataclysmic Variables. VIII. YY Draconis (=3A 1148+719)", Astrophysical Journal, 392: 233, Bibcode:1992ApJ...392..233P, doi:10.1086/171421.

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