OAO/MITSuME Photometry of Dwarf Novae: I SU Ursae Majoris

Abstract

We report on simultaneous $g^{\prime }$, $R_{\mathrm{c}}$ and $I_{\mathrm{c}}$ photometry of SU Ursae Majoris during 2011 December - 2012 February using OAO/MITSuME. Our photometry revealed that quiescence is divided into three types based on the magnitude and color. Quiescent light curves showed complicated profiles with various amplitudes and time scales. Although no superoutbursts were observed during our run, five normal outbursts occurred with intervals of 11 - 21 d. The shapes of the normal outbursts were characteristic of the outside-in type. During the rising phase of a normal outburst, the light curve showed periodic modulations with a period of $\sim$ 0.048111(354) d, but the origin of this peirod was unclear. We examined daily averaged color-color diagram and found that two cycles exist. This implies that the thermal limit cycle in SU UMa is complicated. We newly discovered that $g^{\prime }-R_{\mathrm{c}}$ becomes red about 3 days prior to an outburst. Although the working mechanism on this reddening is unclear, we propose two possibilities: one is that the inner portion of the accretion disk is filled by matter and obscures the central white dwarf, and the other is that the stagnation effect works in the outer region of the accretion disk.

10 pages, 12 figures, PASJ in press

References in corpus (8)

• Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. IV: The Fourth Year (2011-2012)
• The Cause of the Superoutburst in SU UMa Stars is Finally Revealed by Kepler Light Curve of V1504 Cygni
• The Kepler light curves of V1504 Cygni and V344 Lyrae: A study of the Outburst Properties
• Numerical Simulations of Naturally Tilted, Retrogradely Precessing, Nodal Superhumping Accretion Disks
• Discovery of Negative Superhumps during a Superoutburst of January 2011 in ER Ursae Majoris
• Serendipitous Kepler observations of a background dwarf nova of SU UMa type
• Tilt, Warp, and Simultaneous Precessions in Disks
• Discovery of superhumps during a normal outburst of SU Ursae Majoris

Cited by in corpus (2)

• Optical Dual-Band Photometry and Spectroscopy of the WZ Sge-Type Dwarf Nova EZ Lyn during the 2010 Superoutburst
• Photometric analysis of the dwarf nova SU UMa based on TESS