Search Publications
Observation of the Second LIGO/Virgo Event Connected with a Binary Neutron Star Merger S190425z in the Gamma-Ray Range
Minaev, P. Yu.; Pozanenko, A. S.; Grebenev, S. A. +1 more
The results of observations of the gravitational-wave (GW) event S190425z recorded by the LIGO/Virgo detectors with the anti-coincidence shield (ACS) of the SPI gamma-ray spectrometer onboard the INTEGRAL observatory are presented. With a high probability (>99%) it was associated with a neutron star (NS) merger in a close binary system. This is…
The {}(\mathbf{7}) Be Abundance in Nova V5668 Sgr Is Consistent with the Theory
Chugai, N. N.; Kudryashov, A. D.
By now the resonance lines of the isotope ${}7$Be have been detected in five novae. The known estimates of the relative abundance of this isotope from the equivalent widths of ${}7$Be II and Ca II lines lead to the conclusion that the ${}7$Be abundance is considerably higher than the predictions of thermonuclear bu…
Changes in the Period of the Population II Cepheid CC Lyr
Berdnikov, L. N.; Pastukhova, E. N.; Yacob, A. M.
The reduction of all the available photometry for the Cepheid CC Lyr has allowed its $O-C$ diagram spanning a time interval of 124 years to be constructed. The data obtained provide evidence for the existence of large random fluctuations in the period ($\varepsilon/P≈ 0.046$). A formal fitting of the $O-C$ residuals has made it possible to estimat…
Search for Evolutionary Changes in the Period the Cepheid ET Vul
Berdnikov, L. N.; Pastukhova, E. N.
The reduction of all the available photometry for the Cepheid ET Vul has allowed its $O-C$ diagram spanning a time interval of 130 years to be constructed. This has made it possible to calculate for the first time the rate of evolutionary decrease in the period, $dP/dt=-426.5(±{29.7})$ s yr${}^{-1}$, in agreement with the results of model calculat…
Optical Identification of Four Hard X-ray Sources from the INTEGRAL Sky Surveys
Medvedev, P. S.; Sazonov, S. Yu.; Eselevich, M. V. +8 more
We continue the study begun in Karasev et al. (2018) and present the results of our optical identifications of four hard X-ray sources from the INTEGRAL sky surveys. Having first improved the positions of these objects in the sky with the X-ray telescope (XRT) of the Swift observatory, we have identified their counterparts using optical and infrar…
Search for Evolutionary Changes in the Period of the Classical Cepheid EV Aql
Berdnikov, L. N.
The reduction of all the available photometry for the Cepheid EV Aql has allowed its $O-C$ diagram spanning a time interval of 130 years to be constructed. This has made it possible to calculate the rate of evolutionary decrease in the period, $dP/dt=-33.2({±}{6.9})$ s yr${}^{-1}$, in agreement with the results of model calculations for the second…