Precursor flares in OJ 287

We have studied three most recent precursor flares in the light curve of the blazar OJ 287 while invoking the presence of a precessing binary black hole in the system to explain the nature of these flares. Precursor flare timings from the historical light curves are compared with theoretical predictions from our model that incorporate effects of an accretion disk and post-Newtonian description for the binary black hole orbit. We find that the precursor flares coincide with the secondary black hole descending towards the accretion disk of the primary black hole from the observed side, with a mean z-component of approximately z_c = 4000 AU. We use this model of precursor flares to predict that precursor flare of similar nature should happen around 2020.96 before the next major outburst in 2022.

Spectroscopic and Photometric Study of the Contact Binary BO CVn

We present the results of the study of the contact binary system BO CVn. We have obtained physical parameters of the components based on combined analysis of new, multi-color light curves and spectroscopic mass ratio. This is the first time the latter has been determined for this object. We derived the contact configuration for the system with a very high filling factor of about 88 percent. We were able to reproduce the observed light curve, namely the flat bottom of the secondary minimum, only if a third light has been added into the list of free parameters. The resulting third light contribution is significant, about 20-24 percent, while the absolute parameters of components are: M1=1.16, M2=0.39, R1=1.62 and R2=1.00 (in solar units). The O-C diagram shows an upward parabola which, under the conservative mass transfer assumption, would correspond to a mass transfer rate of dM/dt = 6.3 times 10-8Modot/yr, matter being transferred from the less massive component to the more massive one. No cyclic, short-period variations have been found in the O-C diagram (but longer-term variations remain a possibility)

CGCG 292-057 - a radio galaxy with merger-modulated radio activity

We announce the discovery of a unique combination of features in a radio source identified with the merger galaxy CGCG 292-057. The radio galaxy both exhibits a highly complex, X-like structure and shows signs of recurrent activity in the form of double-double morphology. The outer lobes of CGCG 292-057 are characterized by low radio power, P_{1400MHz} simeq 2 * 10^{24} WHz^{-1}, placing this source below the FRII/FRI luminosity threshold, and are highly polarized (almost 20 per cent at 1400 MHz) as is typical of X-shaped radio sources. The host is a LINER-type galaxy with a relatively low black hole mass and double-peaked narrow emission lines. These features make this galaxy a primary target for studies of merger-triggered radio activity.

Physical parameters of components in close binary systems: V

The paper presents combined spectroscopic and photometric orbital solutions for ten close binary systems: CN And, V776 Cas, FU Dra, UV Lyn, BB Peg, V592 Per, OU Ser, EQ Tau, HN UMa and HT Vir. The photometric data consist of new multicolor light curves, while the spectroscopy has been recently obtained within the radial velocity program at the David Dunlap Observatory (DDO). Absolute parameters of the components for these binary systems are derived. Our results confirm that CN And is not a contact system. Its configuration is semi-detached with the secondary component filling its Roche lobe. The configuration of nine other systems is contact. Three systems (V776 Cas, V592 Per and OU Ser) have high (44-77%) and six (FU Dra, UV Lyn, BB Peg, EQ Tau, HN UMa and HT Vir) low or intermediate (8-32%) fill-out factors. The absolute physical parameters are derived.

Physical parameters of close binary systems: VI

New high-quality CCD photometric light curves for the W UMa-type systems V410 Aur, CK Boo, FP Boo, V921 Her, ET Leo, XZ Leo, V839 Oph, V2357 Oph, AQ Psc and VY Sex are presented. The new multicolor light curves, combined with the spectroscopic data recently obtained at David Dunlap Observatory, are analyzed with the Wilson-Devinney code to yield the physical parameters (masses, radii and luminosities) of the components. Our models for all ten systems resulted in a contact configuration. Four binaries (V921 Her, XZ Leo, V2357 Oph and VY Sex) have low, while two (V410 Aur and CK Boo) have high fill-out factors. FP Boo, ET Leo, V839 Oph and AQ Psc have medium values of the fill-out factor. Three of the systems (FP Boo, V921 Her and XZ Leo) have very bright primaries as a result of their high temperatures and large radii.