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We present a summary of the results of the OJ 287 observational campaign, which was carried out during the 2021/2022 observational season. This season is special in the binary model because the major axis of the precessing binary happens to lie almost exactly in the plane of the accretion disc of the primary. This leads to pairs of almost identical impacts between the secondary black hole and the accretion disk in 2005 and 2022. In 2005, a special flare called “blue flash” was observed 35 days after the disk impact, which should have also been verifiable in 2022. We did observe a similar flash and were able to obtain more details of its properties. We describe this in the framework of expanding cloud models. In addition, we were able to identify the flare arising exactly at the time of the disc crossing from its photo-polarimetric and gamma-ray properties. This is an important identification, as it directly confirms the orbit model. Moreover, we saw a huge flare that lasted only one day. We may understand this as the lighting up of the jet of the secondary black hole when its Roche lobe is suddenly flooded by the gas from the primary disk. Therefore, this may be the first time we directly observed the secondary black hole in the OJ 287 binary system.

The bright blazar OJ~287 routinely parades high brightness bremsstrahlung flares, which are explained as being a result of a secondary supermassive black hole (SMBH) impacting the accretion disc of a more massive primary SMBH in a binary system. The accretion disc is not rigid but rather bends in a calculable way due to the tidal influence of the secondary. Below we refer to this phenomenon as a variable disc level. We begin by showing that these flares occur at times predicted by a simple analytical formula, based on general relativity inspired modified Kepler equation, which explains impact flares since 1888. The 2022 impact flare, namely flare number 26, is rather peculiar as it breaks the typical pattern of two impact flares per 12-year cycle. This is the third bremsstrahlung flare of the current cycle that follows the already observed 2015 and 2019 impact flares from OJ~287. It turns out that the arrival epoch of flare number 26 is sensitive to the level of primary SMBH's accretion disc relative to its mean level in our model. We incorporate these tidally induced changes in the level of the accretion disc to infer that the thermal flare should have occurred during July-August 2022, when it was not possible to observe it from the Earth. Thereafter, we explore possible observational evidence for certain pre-flare activity by employing spectral and polarimetric data from our campaigns in 2004/05 and 2021/22. We point out theoretical and observational implications of two observed mini-flares during January-February 2022., Comment: 29 pages, 6 figures, 1 table. arXiv admin note: text overlap with arXiv:2209.08360

The latest results of a survey are presented, which explores the data releases of the ESA-Gaia mission, in order to study the multiplicity of exoplanet host stars, located at distances closer than about 625 pc around the Sun. In total, 280 binaries, 27 hierarchical triples, and one quadruple stellar systems are detected among 1898 exoplanet host stars, whose multiplicity is investigated, yielding a multiplicity rate of at least 16%. The equidistance and the common proper motion of all detected companions and their exoplanet host stars are proven with their accurate Gaia astrometry. Companions with masses in the range between about 0.015 and 1.7 Msun are detected, which exhibit projected separations to the exoplanet host stars between about 30 and 10000 au. Beside many low-mass main sequence stars also 14 brown dwarfs are identified as companions of exoplanet host stars. In addition, 15 white dwarf companions are detected, whose true nature is revealed by their photometric properties. These degenerated companions and the exoplanet host stars form evolved stellar systems with exoplanets, which have survived (physically but also dynamically) the post main sequence evolution of the former primary stars in these systems.

In order to determine the true impact of stellar multiplicity on the formation and on the evolution of planets, we have initiated direct imaging surveys to detect stellar but also substellar companions of exoplanet host stars on close orbits, whose gravitational impact on the planet bearing disk at first and on formed planets afterwards is expected to be maximal. According to theory these are the most challenging environments for planet formation and evolution but might occur quite frequently in the milky way, due to the large number of multiple star systems found within our galaxy. Here we will show results, obtained so far in the course of our AO and Lucky-imaging campaigns of exoplanet host stars, conducted with NACO at ESO-VLT in Chile for southern and with AstraLux at the Calar Alto Observatory in Spain for northern targets, respectively. In addition, we will introduce our new high contrast imaging survey of southern exoplanet host stars, just recently started with SPHERE at ESO-VLT, and we will present some of the latest results of this project.