Photometry of some more neglected bright cataclysmic variables and candidates

Abstract

As part of an effort to better characterize bright cataclysmic variables (CVs) and related systems which have received little attention in the past light curves of four systems (V504 Cen, KT Eri, Ret 1 and CTCV 2056-3014) are analyzed. For some of these stars no time resolved photometry has been published previously. While flickering is observed in all systems except Ret 1, it is particularly strong in V504 Cen and CTCV 2056-3014. In the latter star, a previously observed 15.4 m period, leading to its tentative classification as an intermediate polar, is probably spurious. Variations on time scales of hundredths of days observed in the pre-outburst light curve of the classical nova KT Eri continue after the outburst but appear not to be strictly periodic. Furthermore, the long term post-outburst light curve exhibits modulations with quasi-periods of quite different length. Thus, these variations cannot be due to aspect related variations in a system with a giant component similar to some recurrent novae. Instead, the system possibly exhibits variations with a period of 0.1952 d which may be orbital. However, any such conclusion still requires confirmation. The absence of flickering in Ret 1 indicates that the system probably does not contain an accretion disk. Instead, the observation of slow variations supports a previous suspicion of low amplitude variability with a period >12 h.

CTCV J2056-3014: An X-Ray-faint Intermediate Polar Harboring an Extremely Fast-spinning White Dwarf

“…Optical photometry of J2056 conducted by Bruch (2018) revealed that the averaged magnitude of the system varies by at least 2.4-mag in comparison with measurements of Augusteijn et al (2010), ranging from V ∼ 17.6 to 15.2 mag, and that it displays strong flickering with an amplitude up to 0.8 mag. Bruch (2018) also suggested that the 15.4-min period claimed by Augusteijn et al (2010) is spurious. Finally, Gaia parallax indicates that J2056 is a nearby system, at a distance (d) of 261.6±7.4 pc (Bailer-Jones et al 2018).…”

“…Here we report on its X-ray properties, which suggest J2056 to be an unusual IP. We also revisit the optical observations of Bruch (2018).…”

“…We revisited the optical photometric observations of J2056 presented by Bruch (2018) with the sole purpose of checking for high-frequency periodicities. This effort was motivated by the detection of pulsation in X-rays (Section 3.2).…”

Cyclic variations with twice the accretion disk precession period in the old nova V603 Aquilae

“…No filters were employed during the observations. Bruch (2018) found that his unfiltered CCD photometry was approximately equivalent to observations in the V band. He used detectors which are more sensitive in the blue than the one used here (KAF 1602E).…”

“…Time was transformed into barycentric Julian Date on the Barycentric Dynamical Time (TDB) scale using the online tool provided by Eastman et al (2010). For subsequent data analysis the MIRA software system Bruch (1993) was employed. A journal of observation is given in Table 1.…”