Superhumps in cataclysmic binaries. XXIII. V442 ophiuchi and RX J1643.7+3402

Joseph Patterson, William H. Fenton, John R. Thorstensen, David A. Harvey, David R. Skillman, Robert E. Fried, Berto Monard, Darragh O'Donoghue, Edward Beshore, Brian Martin, Panos Niarchos, Tonny Vanmunster, Jerry Foote, Greg Bolt, Robert Rea, Lewis M. Cook, Neil Butterworth, Matt Wood

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


We report the results of long observing campaigns on two novalike variables: V442 Ophiuchi and RX J1643.7+3402. These stars have high-excitation spectra, complex line profiles signifying mass loss at particular orbital phases, and similar orbital periods (respectively, 0.12433 and 0.12056 days). They are well-credentialed members of the SW Sex class of cataclysmic variables. Their light curves are also quite complex. V442 Oph shows periodic signals with periods of 0.12090(8) and 4.37(15) days, and RX J1643.7+3402 shows similar signals at 0.11696(8) and 4.05(12) days. We interpret these short and long periods, respectively, as a "negative superhump" and the wobble period of the accretion disk. The superhump could then possibly arise from the heating of the secondary (and structures fixed in the orbital frame) by inner-disk radiation, which reaches the secondary relatively unimpeded since the disk is not coplanar. At higher frequencies, both stars show another type of variability: quasi-periodic oscillations with a period near 1000 s. Underlying these strong signals of low stability may be weak signals of higher stability. Similar quasi-periodic oscillations, and negative superhumps, are quite common features in SW Sex stars. Both can in principle be explained by ascribing strong magnetism to the white dwarf member of the binary; and we suggest that SW Sex stars are borderline AM Herculis binaries, usually drowned by a high accretion rate. This would provide an ancestor channel for AM Hers, whose origin is still mysterious.

Original languageEnglish (US)
Pages (from-to)1364-1381
Number of pages18
JournalPublications of the Astronomical Society of the Pacific
Issue number802
StatePublished - 2003

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Superhumps in cataclysmic binaries. XXIII. V442 ophiuchi and RX J1643.7+3402'. Together they form a unique fingerprint.

Cite this