902 citations
Counting papers with at most 25 authors, so collaboration author lists do not stand in for the people here.
- Bulgarian Academy of SciencesBG224 papers
- Centre National de la Recherche ScientifiqueFR67 papers
- Sofia University "St. Kliment Ohridski"BG64 papers
- Shumen UniversityBG62 papers
- Instituto de Astrofísica de CanariasES57 papers
- Instituto de Astrofísica de AndalucíaES55 papers
- National Institute for AstrophysicsIT54 papers
- Universidad de La LagunaES50 papers
- Astronomical ObservatoryRS48 papers
- Evgeni Kharadze Georgian National Astrophysical ObservatoryGE45 papers
- Aryabhatta Research Institute of Observational SciencesIN43 papers
- Osservatorio Astrofisico di TorinoIT43 papers
30 papers · 1 filter
Light curve solutions of 12 eccentric Kepler binaries and analysis of their out-of-eclipse variability
Diana Kjurkchieva, Doroteya Vasileva, Dinko Dimitrov
The eccentricity, periastron angle, orbital inclination, mass ratio, stellar temperatures and relative stellar radii of 12 eclipsing eccentric binaries were determined on the basis…
Synchrotron emission from the blazar PG 1553+113. An analysis of its flux and polarization variability
C. M. Raiteri, F. Nicastro, A. Stamerra +4
In 2015 July 29 - September 1 the satellite XMM-Newton pointed at the BL Lac object PG 1553+133 six times, collecting data for 218 hours. During one of these epochs, simultaneous o…
The cataclysmic variable AE Aquarii: B-V colour of the flares
R. K. Zamanov, G. Y. Latev, S. Boeva +3
We report simultaneous observations of the flaring behaviour of the cataclysmic variable star AE Aqr. The observations are in Johnson B and V bands. The colour-magnitude diagrams (…
Optical light curves of FUor and FUor-like objects
E. Semkov, S. Peneva, S. Ibryamov
Using recent data from photometric monitoring and data from the photographic plate archives we aim to study, the long-term photometric behavior of FUors. The construction of the hi…
Magnetic field structure in single late-type giants: The weak G-band giant 37 Comae from 2008 to 2011
Svetla Tsvetkova, Pascal Petit, Renada Konstantinova-Antova +5
This work studies the magnetic activity of the late-type giant 37 Com. This star belongs to the group of weak G-band stars that present very strong carbon deficiency in their photo…
Multiband optical variability of the blazar OJ 287 during its outbursts in 2015 -- 2016
Alok C. Gupta, A. Agarwal, A. Mishra +31
We present recent optical photometric observations of the blazar OJ 287 taken during September 2015 -- May 2016. Our intense observations of the blazar started in November 2015 and…
Long-term photometric behavior of the PMS stars V977 Cep and V982 Cep in the vicinity of NGC 7129
Sunay I. Ibryamov, Evgeni H. Semkov, Teodor R. Milanov +1
Long-term BVRI photometric light curves of the pre-main sequence stars V977 Cep and V982 Cep during the period from 2000 October to 2016 August are presented. The stars are located…
A collimated wind interpretation for the spectral variability of Z And during its major 2006 eruption
N. A. Tomov, M. T. Tomova, D. V. Bisikalo
High-resolution observations in the region, centered at 4400 Å and those of the lines HeII 4686, Hbeta and HeI 6678 of the spectrum of the symbiotic binary Z And were performed dur…
Return of the King: Time-Series Photometry of FO Aquarii's Initial Recovery from its Unprecedented 2016 Low State
Colin Littlefield, Peter Garnavich, Mark R. Kennedy +28
In 2016 May, the intermediate polar FO~Aqr was detected in a low state for the first time in its observational history. We report time-resolved photometry of the system during its…
The Extremes in Intra-Night Blazar Variability: The S4 0954+65 Case
Rumen Bachev, Anton Strigachev, Evgeni Semkov +4
We present results of optical observations of the extremely violently variable blazar S4 0954+65 on intra-night time scales. The object showed flux changes of up to 100% within a f…
Chandra View of Magnetically Confined Wind in HD191612: Theory versus Observations
Yael Naze, Asif ud-Doula, Svetozar A. Zhekov
High-resolution spectra of the magnetic star HD191612 were acquired using the Chandra X-ray observatory at both maximum and minimum emission phases. We confirm the flux and hardnes…
Multifrequency Photo-polarimetric WEBT Observation Campaign on the Blazar S5 0716+714: Source Microvariability and Search for Characteristic Timescales
G. Bhatta, Ł. Stawarz, M. Ostrowski +43
Here we report on the results of the WEBT photo-polarimetric campaign targeting the blazar S5~0716+71, organized in March 2014 to monitor the source simultaneously in BVRI and near…
AG Pegasi - now a classical symbiotic star in outburst?
T. V. Tomov, K. A. Stoyanov, R. K. Zamanov
Optical spectroscopy study of the recent AG Peg outburst observed during the second half of 2015 is presented. Considerable variations of the intensity and the shape of the spectra…
Chandra Observes the End of an Era SN 1987A
Kari A. Frank, Svetozar A. Zhekov, Sangwook Park +3
Updated imaging and photometric results from Chandra observations of SN 1987A, covering the last 16 years, are presented. We find that the 0.5-2 keV light curve has remained consta…
Active phases and flickering of a symbiotic recurrent nova T CrB
Krystian Ilkiewicz, Joanna Mikolajewska, Kiril Stoyanov +2
T CrB is a symbiotic recurrent nova known to exhibit active phases, characterised by apparent increases in the hot component temperature and the appearance of flickering, i.e. chan…
Exceptional outburst of the blazar CTA 102 in 2012: The GASP-WEBT campaign and its extension
V. M. Larionov, M. Villata, C. M. Raiteri +49
After several years of quiescence, the blazar CTA 102 underwent an exceptional outburst in 2012 September-October. The flare was tracked from gamma-ray to near-infrared frequencies…
The B and Be States of the Star EM Cepheus
Diana Kjurkchieva, Dragomir Marchev, T. A. A. Sigut +1
We present eleven years of high-resolution, spectroscopic observations for the star EM~Cep. EM~Cep switches between B and Be star states, as revealed by the level of H emission,…
Recent X-Recent X-ray observations of the symbiotic star AG Peg: do they signify Colliding Stellar Winds?
Svetozar A. Zhekov, Toma Tomov
We present an analysis of recent X-ray observations of the symbiotic star AG Peg. The X-ray emission of AG Peg as observed with Swift in 2015 shows considerable variability on time…
YETI observations of the young transiting planet candidate CVSO 30 b
St. Raetz, T. O. B. Schmidt, S. Czesla +32
CVSO 30 is a unique young low-mass system, because, for the first time, a close-in transiting and a wide directly imaged planet candidates are found around a common host star. The…
Discovery of a complex linearly polarized spectrum of Betelgeuse dominated by depolarization of the continuum
M. Aurière, A. López Ariste, P. Mathias +15
Betelgeuse is an M supergiant that harbors spots and giant granules at its surface and presents linear polarization of its continuum. We have previously discovered linear polarizat…
Homologous prominence non-radial eruptions: A case study
P. Duchlev, K. Koleva, M. S. Madjarska +1
The present study provides important details on homologous eruptions of a solar prominence that occurred in active region NOAA 10904 on 2006 August 22. We report on the preeruptive…
Photometric observations and light curve solutions of the W UMa stars NSVS 2244206, NSVS 908513, CSS J004004.7+385531 and VSX J062624.4+570907
D. Kjurkchieva, V. A. Popov, D. Vasileva +1
Photometric observations in Sloan g' and i' bands of four W UMa stars, NSVS 2244206, NSVS 908513, CSS J004004.7+385531, VSX J062624.4+570907, are presented. The light curve solutio…
Optical spectroscopy of Be/gamma-ray binaries
R. K. Zamanov, K. A. Stoyanov, J. Marti +4
We report optical spectroscopic observations of the Be/gamma-ray binaries LSI+61303, MWC 148 and MWC 656. The peak separation and equivalent widths of prominent emission lines (H-a…
The different origins of magnetic fields and activity in the Hertzsprung gap stars, OU Andromedae and 31 Comae
A. Borisova, M. Aurière, P. Petit +3
Context: When crossing the Hertzsprung gap, intermediate-mass stars develop a convective envelope. Fast rotators on the main sequence, or Ap star descendants, are expected to becom…