Search Publications
On the flux saturation of SOHO/ERNE proton events
Miteva, Rositsa; Dechev, Momchil; Samwel, Susan W. +1 more
This study lists the main procedures completed on the analysis of solar proton events using data from the SOHO/ERNE high energy detector in the period 1996$-$2017. The highest possible temporal resolution of 1 minute is used here. The proton fluxes from the two analyzed energy channels, at $\sim$25 and $\sim$50 MeV, are compared with the respectiv…
Kinematical structure of open clusters within 1 kpc by Gaia
Elsanhoury, W. H.
The work is based on proper motions, radial velocities, and absolute magnitudes of 56 open clusters located within 1 kpc. We classify those as a function of their distances into five groups (Freedman and Diaconis's rule) as well as a double frequency table may be achieved. For these groups, we calculated their velocity ellipsoid parameters VEPs, e…
Gaia DR2 and Serbian-Bulgarian investigations
Damljanović, Goran
On April $25^{th}$ 2018, the second release of the Gaia catalog (DR2) appeared. It is based on 640 days of Gaia satellite observations; GAIA means Global Astrometric Interferometer for Astrophysics. The observing period was August $22^{nd}$ 2014 - May $23^{rd}$ 2016 (1.75 yr or 21 months with some interruptions). The reference epoch is J2015.5 . T…
High-resolution optical spectroscopy of Nova V392 Per
Stoyanov, K. A.; Georgiev, S.; Stateva, I. +1 more
Here we analyze high-resolution spectra of the Nova V392 Per obtained during the 2018 outburst. The Hα and Hβ emission lines show a triple-peak structure with radial velocities of about -2000 km/s, -250 km/s and 1900 km/s respectively. The near infrared spectrum is dominated by the narrow and single-peaked Paschen lines of hydrogen and the O I λ84…
Comparison of photometric results between the Serbian and Bulgarian telescopes and activities in line with Gaia Alerts (Gaia-FUN-TO)
Damljanović, Goran; Cvetković, Zorica; Pavlović, Rade +5 more
We established the cooperation "Serbian-Bulgarian mini-network telescopes" in 2013, as well as two SANU-BAN joint research projects ("Observations of ICRF radio-sources visible in optical domain" during 2014-2016, and "Study of ICRF radio-sources and fast variable astronomical objects" for the period 2017-2019). Here, some main results of that coo…
New light curve solution of V568 Peg and first determination of its fundamental parameters
Kjurkchieva, Diana; Ibryamov, Sunay
We present V, R_c photometric observations of the short-period W UMa star V568 Peg. They allowed us to improve its period. The light curve solution revealed that V568 Peg is an overcontact binary of A subtype with moderate fill-out factor. Its components are K stars which undergo partial eclipses. The mass ratio was estimated by q-search analysis.…
Two computer programs for studying stellar evolution
Kosmas, T. S.; Liolios, T. E.; Karathanou, G. I. +1 more
Two FORTRAN programs are presented which plot the Hertzsprung-Russell diagram and the temporal evolution of such stellar quantities as: central and photospheric isotopic abundances, central densities and temperatures, luminocities, effective temperatures and photospheric radii for a wide range of stellar masses. The programs, which are modificatio…