High-speed photometry of the eclipsing polar UZ Fornacis

Abstract

We present 33 new mid-eclipse times spanning approximately eight years of the eclipsing polar UZ Fornacis. We have used our new observations to test the two-planet model previously proposed to explain the variations in its eclipse times measured over the past ∼35 years. We find that the proposed model does indeed follow the general trend of the new eclipse times, however, there are significant departures. In order to accommodate the new eclipse times, the two-planet model requires that one or both of the planets require highly eccentric orbits, that is, e ≥ 0.4. Such multiple planet orbits are considered to be unstable. Whilst our new observations are consistent with two cyclic variations as previously predicted, significant residuals remain. We conclude that either additional cyclic terms, possibly associated with more planets, or other mechanisms, such as the Applegate mechanism are contributing to the eclipse time variations. Further long-term monitoring is required.

Multi-wavelength study of the eclipsing polar UZ Fornacis

“…The shape of the eclipse is similar to those recorded in the literature (e.g. Bailey & Cropper 1991;Khangale et al 2019) and the out-of-eclipse shape of the light curve is similar to that of Perryman et al (2001).…”

“…We calculated the phases using the ephemeris listed in Khangale et al (2019). We corrected all the times for the light travel-time to the barycentre of the solar system (i.e.…”

A spectroscopic, photometric, polarimetric, and radio study of the eclipsing polar UZ Fornacis: the first simultaneous SALT and MeerKAT observations

“…The shape of the eclipse is similar to those recorded in the literature (e.g. Bailey & Cropper 1991;Khangale et al 2019) and the out-of-eclipse shape of the light curve is similar to that of Perryman et al (2001). (at 4120, 4144, 4367, 4471, 4713, 4921 and 5017Å).…”

“…Both the processing as well as the photometric calibration will be full discussed in a forthcoming paper. As with shoc data, the we converted the times from MJD to BJD and calculated the phases using the ephemeris from Khangale et al (2019). The resulting lightcurve is shown in Fig.…”

“…They determined magnetic field strengths of 51 and 74 MG for the bright and faint phase, respectively. The distance to UZ For was estimated to be ∼240 pc by Khangale et al (2019) based on G AI A parallax measurements. Prior to this study, there has not been any circular spectropolarimetry results presented for this target.…”