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QQ Vulpeculae is a cataclysmic variable binary star system in the northern constellation of Vulpecula, abbreviated QQ Vul. It has a brightness that fluctuates around an apparent visual magnitude of 14.7,[3] which is too faint to be viewed with the naked eye. The distance to this system is approximately 981 light years based on parallax measurements.[2]

QQ Vulpeculae

A blue band light curve for QQ Vulpeculae, adapted from Nousek et al. (1984)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Vulpecula
Right ascension 20h 05m 41.909s[2]
Declination 22° 39′ 58.84″[2]
Apparent magnitude (V) 14.656[3]
Characteristics
Spectral type M4V[4]
Apparent magnitude (B) 14.4 to 17.0[5]
Variable type Polar[5]
Astrometry
Proper motion (μ) RA: −3.249 mas/yr[2]
Dec.: −14.882 mas/yr[2]
Parallax (π)3.3235 ± 0.0286 mas[2]
Distance981 ± 8 ly
(301 ± 3 pc)
Orbit[6]
Period (P)0.1545217±0.0000022 d
Semi-major axis (a)1.14±0.12 R☉[4]
Eccentricity (e)0.00
Inclination (i)≥ 72[7]°
Periastron epoch (T)2,445,234.8364±0.0018 JD
Semi-amplitude (K1)
(primary)		369.00 km/s
Semi-amplitude (K2)
(secondary)		219±6[4] km/s
Details
White dwarf
Mass0.58–0.66[7] M☉
Radius0.01[8] R☉
Donor star
Mass0.34–0.44[7] M☉
Radius0.35±0.10[4] R☉
Rotational velocity (v sin i)110±15[4] km/s
Other designations
E 2003+225, QQ Vul, IRAS J20054191+2239587[9]
Database references
SIMBADdata

This system was detected as a soft X-ray source using the HEAO-1 satellite during 1977–78. The Einstein Observatory was then used in 1981 to more precisely position the source, which was designated E 2003+225.[1] In 1982, J. A. Nousek and associates observed the optical counterpart and found it varied in brightness with a period of 3.706 hours, displaying strong emission lines of hydrogen and helium. They identified it as a variable of the AM Herculis type.[10] The system shows a brightness variation of 0.7 magnitude during each orbit, plus a short-term flickering of 0.2 magnitudes.[1]

The accepted model for this class of variable is a binary system with a red dwarf secondary in a close orbit with a magnetic white dwarf. The red dwarf is overflowing its Roche lobe and matter is streaming onto the white dwarf.[11] The magnetic field of the white dwarf draws this material toward the magnetic poles, and the material is heated to a sufficient temperature to emit X-rays.[12] In 1985, a weak, extended radio source was detected at the location of this system, suggesting it may be a remnant of a past nova event.[13] X-ray observations in 1991 suggested there are separate regions of hard and soft X-ray emission, indicating matter is being accreted along two poles. The soft X-ray site is likely at the magnetic pole furthest from the secondary star.[12]

The strength of the magnetic field in the white dwarf is estimated at ~30 MG. Over long periods, the system has been shown to switch between states of high and low brightness.[8] K. Mukai and associates in 1986 suggested that the primary dip in the light curve is due to the geometry of the system in combination with a partial eclipse of the primary accretion region by the accretion column. The secondary dip may be caused by the limb of the white dwarf partially eclipsing the active accretion region. The rotation period of the white dwarf appears to be locked to the orbital period.[8]


References


  1. Nousek, J. A.; et al. (February 1984), "E 2003+225 : a 3h42m AM Herculis type binary system.", Astrophysical Journal, 277: 682–691, Bibcode:1984ApJ...277..682N, doi:10.1086/161739.
  2. 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. Zacharias, N.; et al. (February 2013), "The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)", The Astronomical Journal, 145 (2): 44, arXiv:1212.6182, Bibcode:2013AJ....145...44Z, doi:10.1088/0004-6256/145/2/44, S2CID 119299381.
  4. Catalán, M. S.; et al. (November 1999), "Mapping the secondary star in QQ Vulpeculae", Monthly Notices of the Royal Astronomical Society, 310 (1): 123–145, Bibcode:1999MNRAS.310..123C, doi:10.1046/j.1365-8711.1999.02972.x.
  5. 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.
  6. Osborne, J. P.; et al. (August 1986), "A multi-wavelength study of the long-period AM Her system E2003+225 -I. The soft X-ray light curve and overall energy spectrum", Monthly Notices of the Royal Astronomical Society, 221 (4): 823–838, Bibcode:1986MNRAS.221..823O, doi:10.1093/mnras/221.4.823.
  7. Watson, C. A.; et al. (May 2003), "Roche tomography of cataclysmic variables - II. Images of the secondary stars in AM Her, QQ Vul, IP Peg and HU Aqr", Monthly Notices of the Royal Astronomical Society, 341 (1): 129–142, arXiv:astro-ph/0302115, Bibcode:2003MNRAS.341..129W, doi:10.1046/j.1365-8711.2003.06381.x, S2CID 9674397.
  8. Halevin, A. V.; et al. (October 2002), "Unstable processes in magnetic cataclysmic variables. I. Case of the long-period polar QQ Vulpeculae", Astronomy and Astrophysics, 394: 171–179, Bibcode:2002A&A...394..171H, doi:10.1051/0004-6361:20021107, S2CID 121896072.
  9. "QQ Vul". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-09-02.
  10. Nousek, J.; et al. (October 1982), Marsden, B. G. (ed.), "E2003+225", IAU Circular, vol. 3733, p. 2, Bibcode:1982IAUC.3733....2N.
  11. Mukai, K.; et al. (February 1985), "X-Ray Optical and Ultraviolet Observations of the AM-Herculis System E2003+225", Space Science Reviews, 40 (1–2): 151–155, Bibcode:1985SSRv...40..151M, doi:10.1007/BF00212879, S2CID 119871749.
  12. Beardmore, A. P.; et al. (April 1995), "ROSAT and GINGA observations of the magnetic cataclysmic variable QQ Vul: evidence for two-pole accretion", Monthly Notices of the Royal Astronomical Society, 273 (3): 742–750, Bibcode:1995MNRAS.273..742B, doi:10.1093/mnras/273.3.742.
  13. Takalo, L. O.; Nousek, J. A. (June 1985), "E2000+223: a newly discovered old nova?", Publications of the Astronomical Society of the Pacific, 97: 570–574, Bibcode:1985PASP...97..570T, doi:10.1086/131569, S2CID 122502321.

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