Outputs

Variable stars in 2022

24/02/2023 by dpv

Thanks to a fortunate time-space configuration, signals about several interesting phenomena in our Galaxy reached Earth during 2022. In this post I will summarize the basic information about some of them.

First of all, novae that exploded in the period of 2020, 2021 were still active. Of them, I will mention two completely opposite objects. V1405 Cas is a very slow nova with multiple maxima and brightness variations. By the end of 2022, it was already in the nebular stage, but still brighter than 12 mag. And short-period variations with a characteristic time similar to the orbital period also appeared. However, there is no stable signal corresponding to the orbital period. In the world of cataclysmic variable stars, such behavior is usually called quasi-periodic oscillations. It will require a detailed periodic analysis. Fig. 1 shows the last few light curves.

Fig. 1. V1405 Cas – light curves in the V filter obtained by fast photometry at the 60 cm Csere telescope in Hlohovec and the 35 cm Celestron in Kolonica. From left to right 22.9.2022, 20.10.2022, 28.11.2022 and 1.12.2022.

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Greatest hits 2021

18/12/2021 by dpv

Unprecedented rate of novae for northern observers. Final count is six in one year included the recurrent symbiotic nova RS Oph as the most important event. The photometric an spectroscopic coverage made at the Kolonica observatory is also unprecedented. The first results were presented at the Bezovec conference and will be published in the proceedings. In this article let me demonstrate the variety of light curves of these objects and how dense was our coverage. For more details see the presentation.

Besides the novae few words should be dedicated to SS Cyg. The prototype of regular dwarf novae systems. After more than century of periodic outbursts it presented typical Z Cam type behavior = standstill.

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MU Cam – orbital sidebands

18/12/2019 by dpv

Long term monitoring of intermediate polars is performed as a part of the InterLongitude Astronomy campaign. High quality and long time series observations allow us to investigate fine effects on complex light curves. In
the case of MU Cam we have investigated the periodic modulation of the spin phases with the orbital phase. This dependency was already described by Kim et al. (2005). As an explanation they proposed inhomogeneous accretion flow from the secondary. However based on our new data we can propose simple explanation as the influence of orbital sidebands in the periodic signal produced by intermediate polar. This explanation is supported by the fact that the changes in spin maxima phase are observed mainly when the sideband frequency is dominant in the periodogram. This result was presented on conferences in Bezovec and Telč.

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Low states of intermediate polars

02/01/2019 by dpv

The by-product of long term monitoring of intermediate polars is the discovery of low states similar to the low states in classical polars. Up to now we know that such phenomenon was observed in V1323 Her, FO Aqr, DO Dra.

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Flares on red dwarfs

01/01/2019 by dpv

By-product of the Project dwarf are the observation of flares on red dwarf in binary systems. The project dwarf is aimed at detection of circumbinary extrasolar planets using the timing of the minima of low-mass eclipsing binaries. There are many red dwarf stars among the observed objects. Thus time to time some flare was detected. Object GJ3236 turned to be the most active one. Another one was AD Leo, subject of 2019 campaign

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Visual observations

30/12/2018 by dpv

Light curves of several semiregular and symbiotic variables from my program. Visual estimates together with data from ASAS-SN survey and CCD observations from AAVSO database. Some time visual data are useful (WY And), sometime the advantage of one visual observer is visible (CH Cyg), sometime visual data fill the gap in the survey data (TZ Cep), sometime visual observation are completely wrong (CK Vir).

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