A Photometric and Spectroscopic Study of the Cataclysmic Variable SX Leonis Minoris in Quiescence and Superoutburst
Abstract
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. Observations reported in this paper were obtained at the Multiple Mirror Telescope, a joint facility of the University of Arizona and the Smithsonian Institution. Based in part on observations obtained at the Michigan-Dartmouth-MIT Observatory. Based on observations obtained at the National Undergraduate Research Observatory.
- Publication:
-
The Astronomical Journal
- Pub Date:
- February 1998
- DOI:
- 10.1086/300201
- Bibcode:
- 1998AJ....115..787W
- Keywords:
-
- Cataclysmic Variables;
- Stellar Spectrophotometry;
- Variable Stars;
- Binary Stars;
- Astrometry;
- Charge Coupled Devices;
- Light Curve;
- Radial Velocity;
- Least Squares Method;
- Astrophysics;
- BINARIES: GENERAL;
- STARS: INDIVIDUAL: SX LEONIS MINORIS;
- STARS: VARIABLES: OTHER