DO Draconis/YY Draconis

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DO Draconis/YY Draconis

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]
Distance
639 ± 3 ly
(196 ± 1 pc)
Semi-amplitude (K1)
(primary)
87±13[5] km/s
Semi-amplitude (K2)
(secondary)		184±10[5] km/s
Details
Accreting white dwarf
Rotational velocity (v sin i)
86±15[5] km/s
DO Dra or YY Dra, 3A 1148+719, PG 1140+719, AAVSO 1137+72[9]
Database references
SIMBADdata

YY Draconis and DO Draconis are separate

light years from the Sun.[3]

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

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,

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

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]

References

  1. S2CID 18374995
    . Retrieved 26 May 2023.
  2. S2CID 247187776
    .
  3. ^
    doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR
    .
  4. ^
    S2CID 125853869
    .
  5. ^
    doi:10.1086/169823
    .
  6. ^
    Bibcode:2013ASInC...9...80J
    .
  7. ^
    S2CID 121217299
    .
  8. ^
    S2CID 121358198
    .
  9. ^ "DO Dra", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2022-05-16.
  10. ^
    Bibcode:1987IBVS.3079....1P
    .
  11. ^
    Bibcode:1983IBVS.2262....1W
    .
  12. S2CID 120644760
    .
  13. Bibcode:1985IAUC.4143....2M
    .
  14. Bibcode:1985IAUC.4130....1H
    .
  15. Bibcode:1988IBVS.3154....1K
    .
  16. arXiv:2203.05091 [astro-ph.SR
    ]
  17. doi:10.1086/171421
    .

Further reading


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