119196445
New cataclysmic variable 1RXS J073346.0+261933 in Gemini
In the course of our search for the optical identifications of ROSAT X-ray sources, we have found a highly variable object with a very unusual behavior on long time scales, rare color indices, and a high X-ray-to-optical flux ratio. We present the archival light curve from the Catalina Sky Survey, optical spectroscopy from RTT150, and time-resolved photometry from the Astrotel-Caucasus telescope. The object appears to be a magnetic cataclysmic variable (a polar) with an orbital period P = 3.20 h.
118487818
Masses and accretion rates of supermassive black holes in active galactic nuclei from the INTEGRAL survey
The masses of 68 supermassive black holes (SMBHs) in nearby (z < 0.15) active galactic nuclei (AGNs) detected by the INTEGRAL observatory in the hard X-ray energy band (17–60 keV) outside the Galactic plane (|b| 5°) have been estimated. Well-known relations between the SMBHmass and (1) the infrared luminosity of the stellar bulge (from 2MASS data) and (2) the characteristics of broad emission lines (from RTT-150 data) have been used. A comparison with the more accurate SMBH mass estimates obtained by the reverberation-mapping technique and from direct dynamical measurements is also made for several objects. The SMBH masses derived from the correlation with the bulge luminosity turn out to be systematically higher than the estimates made by other methods. The ratio of the bolometric luminosity to the critical Eddington luminosity has been found for all AGNs. It ranges from 1 to 100% for the overwhelming majority of objects.
43975531
The eccentric massive binary V380 Cyg: revised orbital elements and interpretation of the intrinsic variability of the primary component
We present a detailed analysis and interpretation of the hig h-mass binary V380 Cyg, based on high-precision space photometry gathered with the Kepler space mission as well as highresolution ground-based spectroscopy obtained with thehermes spectrograph attached to the 1.2m Mercator telescope. We derive a precise orbital solution and the full physical properties of the system, including dynamical component mass estimates of 11.43±0.19 and 7.00±0.14 M⊙ for the primary and secondary, respectively. Our frequency analysis reveals the rotation frequency of the primary in both the photometric and spectroscopic data and additional low-amplitude stochastic variability at low freq uency in the space photometry with characteristics that are compatible with recent theoretic al predictions for gravity-mode oscillations excited either by the convective core or by sub-s urface convective layers. Doppler Imaging analysis of the Silicon lines of the primary suggests the presence of two high-contrast stellar surface abundance spots which are located either at the same latitude or longitude. Comparison of the observed properties of the binary with present-day single-star evolutionary models shows that the latter are inadequate and lack a serious amount of near-core mixing.
118563804
Spectrum analysis of bright Kepler late B- to early F-stars
The Kepler satellite mission was designed to search for transiting exoplanets and delivers single band-pass light curves of a huge number of stars observed in the CygnusLyra region. At the same time, it opens a new window for asteroseismology. In order to accomplish one of the required preconditions for the asteroseismic modelling of the stars, namely knowledge of their precise fundamental parameters, ground-based spectroscopic and/or photometric follow-up observations are needed. We aim to derive fundamental parameters and individual abundances for a sample of 18 Dor/� Sct and 8 SPB/� Cep candidate stars in the Kepler satellite field of view. We use the spectral synthesis method to model newly obtained, high-resolution spectra of 26 stars in order to derive their fundamental parameters like Teff, logg, v sini, �, [M/H], and individual abundances with high accuracy. The stars are then placed into the log(Teff)– log(g) diagram and the obtained spectroscopic classification is compared to the existing photometric one. For most A- and F-type stars, the derived Teff values agree within the measurement errors with the values given in the Kepler Input Catalog (KIC). For hot stars, the KIC temperatures appear to be systematically underestimated, in agreement with previous findings. We also find that the temperatures derived from our spectra agree reasonably well with those derived from the SED fitting. According to their position in the log(Teff)–log(g) diagram, two stars are expected Dor stars,
115150797
Spectrum analysis of bright Kepler γ Doradus candidate stars
Ground-based spectroscopic follow-up observations of the pulsating stars observed by the Kepler satellite mission are needed for their asteroseismic modelling. We aim to derive the fundamental parameters for a sample of 26 γ Doradus candidate stars observed by the Kepler satellite mission to accomplish one of the required pre-conditions for their asteroseismic modelling and to compare our results with the types of pulsators expected from the existing light-curve analysis. We use the spectrum synthesis method to derive the fundamental parameters like T eff ,l ogg, [M/H] and v sini from newly obtained spectra and compute the spectral energy distribution from literature photometry to get an independent measure of T eff. We find that most of the derived T eff values agree with the values given in the Kepler Input Catalog. According to their positions in the HR diagram, three stars are expected γ Dor stars, 10 stars are expected δ Sct stars and seven stars are possibly δ Sct stars at the hot border of the instability strip. Four stars in our sample are found to be spectroscopic binary candidates and four stars have very low metallicity where two show about solar C abundance. Six of the 10 stars located in the δ Sct instability region of the HR diagram show both δ Sct- and γ Dor-type oscillations in their light curves, implying that γ Dor-like oscillations are much more common among the δ Sct stars than predicted by theory. Moreover, seven stars showing periods in the δ Sct and the δ Sct-γ Dor range in their light curves are located in the HR diagram left of the blue edge of the theoretical δ Sct instability strip. The consistency of these findings with recent investigations based on high-quality Kepler data implies the need for a revision of the theoretical γ Dor and δ Sct instability strips.
122640197
The method and results of measurement of the optical parameters of the UHECR detector for the TUS space experiment
Abstract The TUS space experiment is aimed to study the energy spectrum and arrival direction of Ultra High Energy Cosmic Rays (UHECR) at E ~ 10 20 eV . The TUS detector will measure the fluorescence and Cherenkov light radiated by Extensive Air Shower of the UHECR using the optical system that comprises a Fresnel mirror-concentrator of seven modules with a total area of ~ 2 m 2 . The production process of the Fresnel mirror and the method and results of measurement of its optical parameters are presented.