Section: PZ: main journal
The X-Ray Source 1RXS J051439.2--021615 is a Flare K Dwarf
We obtained a spectrum and UBVRI photometry of the star associated with the X-ray source 1RXS J051439.2-021615 that experienced a rapid optical flare on 25 January 2018 (ATel No. 11250). We classified the spectrum as K2V - K5V. The Halpha line was filled with emission. We explain this event as a flare in an active region on the surface of a late-type main sequence star.
Novae in 2018: Official Announcement of GCVS Names
GCVS names are announced for 14 galactic Novae discovered in 2018.
A Study of the New Cataclysmic Variable 2MASS 23212116+3807563
We present our variability study of the new cataclysmic variable star, 2MASS 23212116+3807563. The variable is a U Geminorum type star. An analysis of available electronic archives data (CSS, 1SWASP and ASAS-SN) does not detect periodicity. The variable has a close companion, photometric data in the electronic archives present combined light of the two stars. We acquired the star's new CCD photometry in Johnson's B, V, and R bands. Our observation confirm variability of 2MASS 23212116+3807563 with a large amplitude of light variations (more than 3m).
GSC 02693-00926 and USNO-B1.0 1587-0201409, Two New Doubly Eclipsing Systems
I present my detection of two new doubly eclipsing systems, GSC 02693-00926 and USNO-B1.0 1587-0201409 (types EA+EB and EB+ELL). I analyzed all observations available for these stars in the NSVS and ASAS-SN online public archives using the period-search software developed by Dr. V.P. Goranskij for Windows environment. The light elements of both variations and the parameters of light curves are obtained.
New Eclipsing Cataclysmic Variable Candidate in the Period Gap
We report the discovery of a blue eclipsing variable Dan V1 in Sagittarius with the orbital period P=0.094277 days (2.2626 hours). The object is also an UV source, indicating the presence of a white dwarf in the binary system. We consider two possibilities: a cataclysmic (nova-like) variable and an eclipsing hot subdwarf of the HW Vir type. Our analysis favors the first (CV) scenario. If confirmed, Dan V1 is a very rare eclipsing cataclysmic variable in the period gap.
I present a detection of 44 new double-mode variable stars, of which 25 variables are high-amplitude Delta Scuti stars, HADS(B) type, and 19 stars are RR Lyrae variables, RR(B) type. For two of the HADS(B) stars, their detection was the variability discovery. We analyzed all observations available for these stars in the Catalina Surveys and SuperWASP online public archives using the period-search software developed by Dr. V.P. Goranskij for Windows environment. In two cases, we also used data of the ASAS-SN archive. According to these data, one star, GSC 02900-00317, is possibly pulsating in the first- and second-overtone modes; the other stars are pulsating in the fundamental and first-overtone modes.
Novae in 2015 - 2017: Official Announcement of GCVS Names
GCVS names are announced for 20 galactic Novae discovered in 2015 - 2017.
A Photometric Study of GSC 01374-01131, a HADS Variable Star with an Eclipsing Component
We present the results of our new observations of GSC 01374-01131, a recently discovered high-amplitude delta Scuti (HADS) star for which, in 2013, we detected an eclipsing component of the light curve in the Catalina Surveys data. We acquired new CCD photometry in Johnson's B, V, and R bands for this star, improved the periods of the eclipses (P_e = 5.96857 days) and of the pulsation (P_p = 0.08494573 days) and other parameters of the light curves. GSC 01374-01131 is an eclipsing binary of the Algol type (EA); one of its components is a pulsating HADS star. Currently, GSC 01374-01131 has the lowest depth of the main eclipse (A_e = 0.13 mag) among all known HADS stars in eclipsing binary systems, comparable to the observed pulsation amplitude.
CCD BVRI photometry is presented for two type Ia supernovae, SN 2011df and 2011ek, and for a supernova of type Ia-1991bg, SN 2012ea. The light curve parameters and absolute magnitudes at maximum light are estimated. It is shown that SNe 2011df and 2012ea are typical for their classes considering the shape of their light curves and maximum luminosity. SN 2011ek shows some properties of 1991bg-like supernovae: red color at maximum and low luminosity, but the shape of the light curves is typical of normal SNe Ia.
Unusual Short-period Cepheid with a Prominent Bump
I report my discovery of a peculiar short-period Type II Cepheid in Centaurus. The new variable is pulsating with the period of 2.918 days, yet it is showing a distinctly double-peaked light curve with two nearly equal maxima. The "bumps" are normally observed in long-period Cepheids with periods ranging from 6 to 16 days, but there are exceptions for stars with shorter P values. The new variable resides in the halo, more than 3 kpc above the Galactic plane, and belongs to population II Cepheids of the BL Her type (CWB).