Superhumps Behavior during Normal Outbursts in ER UMa: Spectroscopy and Photometry

Abstract

We have taken a 4-day spectroscopic observation and have been conducting a 13-day photometric study of the SU UMa-type dwarf nova, ER Ursae Majoris. The mean $K$-amplitude for the emission lines is $54\pm 8$ km s${}^{-1}$ and $\gamma$ velocity is 8$\pm 4$ km s${}^{-1}$ from our spectroscopic results. A phase shift of 0.22 is also obtained. Our photometric observation confirms superhumps in normal outbursts of ER UMa and reconciles contradictory observational results obtained by different authors. We find that superhumps possibly develop near each normal outburst maximum and fade out before the next outburst maximum. If the observed humps were not late superhumps but ordinary superhumps, much more theoretical works should be done to explain the new phenomena.

16 pages, 10 figures, accepted for publication in PASJ

References in corpus (5)

• On Echo Outbursts and ER UMa Supercycles in SU UMa-type Cataclysmic Variables
• Superoutbursts, superhumps and the tidal-thermal instability model
• On The Nature Of Superoutbursts In Dwarf Novae
• Spectroscopic Study of SU UMa-type Dwarf Nova YZ Cnc during its 2002 Superoutburst
• Photometry and Spectroscopy of KS Ursae Majoris during Superoutburst

Cited by in corpus (5)

• V344 Lyrae: A Touchstone SU UMa Cataclysmic Variable in the Kepler Field
• SPH Simulations of Negative (Nodal) Superhumps: A Parametric Study
• IX Draconis - a curious ER UMa-type dwarf nova
• Detection of Change in Supercycles in ER Ursae Majoris
• Searching for cataclysmic variable stars in unidentified X-ray sources