Photometric and polarimetric observations of the eclipsing polar SDSS J015543.40+002807.2

Abstract

We present photometric and polarimetric follow-up observations of the eclipsing Sloan Digital Sky Survey cataclysmic variable SDSS J015543.40+002807.2. Linear and circular polarizations were detected, confirming that it is a new polar (AM Herculis system). An accurate eclipse ephemeris yields an orbital period of 87.1435 ± 0.0002 min. Assuming a range of mass ratios 0.11 > M2/M1 > 0.07, the inclination lies in the range 85° < i < 90°. The circular polarization shows a change in sign, implying that SDSS J015543.40+002807.2 is a two-pole accretor, although the possibility that it could be a single-pole accretor cannot yet be ruled out.