A Possible Extremely Fast Spinning White Dwarf in the Intermediate Polar SDSS J0932+47

Abstract

Abstract We analyze the far-ultraviolet light curve of the intermediate polar (IP) candidate SDSS-J093249.57+472523.0 (J0932+47), as observed by Hubble Space Telescope/Cosmic Origins Spectrograph. The power spectrum displays two periodicities at frequencies of 2.01 and 0.462 cycles minute−1, corresponding to periods of 29.8 and 130 s. We estimate the significance of the 29.8 s peak to be 3σ. The detection of the 130 s signal is less secure. If the 29.8 s signal is generated by a rotating white dwarf (WD), then J0932+47 would possess one of the fastest spinning WDs among known IPs. The N v/C iv and Si iv/C iv line ratios are larger than typically seen in cataclysmic variables (CVs), and anomalous line ratios are seen in several CVs with rapidly rotating WDs. Alternatively, the periodicities are in the range typical of dwarf nova oscillations.