A photometric and spectroscopic study of the cataclysmic variable SX Leonis Minoris in quiescence and superoutburst

R. Mark Wagner, John R. Thorstensen, R. K. Honeycutt, S. B. Howell, R. H. Kaitchuck, T. J. Kreidl, J. W. Robertson, E. M. Sion, Sumner Starrfield

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


We present CCD imaging, CCD photometry on long and short timescales, and time-resolved spectroscopy of SX LMi, a new SU Ursae Majoris type dwarf nova. The quiescent optical spectrum shows broad double-peaked Balmer. He I, and He II emission lines, similar to other quiescent dwarf novae. Absorption lines from a late-type secondary are not detected. Time-resolved spectra obtained in quiescence reveal radial velocity variations of the Balmer emission lines on a period of 0.06717 ± 0.00011 days, or 96.72 ± 0.16 minutes, with only a slight possibility of a daily cycle-count error. Optical photometry obtained between 1987 and 1991 shows flickering with a peak-to-peak amplitude of ≃0.18 mag. The binary orbital period can sometimes be seen in the photometric record. Long-term photometric monitoring by Indiana University's robotic telescope RoboScope for a 3 year period between 1992 October and 1995 June shows seven well-defined outbursts and marginally detects a few others. The outburst interval varies between 34 and 64 days. During the 1994 December outburst, optical photometric observations show that SX LMi exhibited superhumps with a period of 0.06893 ± 0.00012 days, which is 2.6% ± 0.2% longer than the orbital period, as expected for a normal SU UMa star at this period. Spectra obtained during superoutburst show dramatic variations in the emission-line profiles on timescales of 10 minutes. Profile fits indicate that underlying absorption contributes to the shape of the Balmer emission-line profiles during superoutburst as in other dwarf novae in outburst or superoutburst. Direct images in good seeing show a ∼19 mag companion star 1″.95 from SX LMi.

Original languageEnglish (US)
Pages (from-to)787-800
Number of pages14
JournalAstronomical Journal
Issue number2
StatePublished - Feb 1998


  • Binaries: General
  • Stars: Individual (SX Leonis Minoris)
  • Stars: Variables: Other

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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