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
28 papers · 1 filter
Density profile of a self-gravitating polytropic turbulent fluid in a rotating disk near to the cloud core
S. Donkov, I. Zh. Stefanov, T. V. Veltchev +1
We obtain two equations (following from two different approaches) for the density profile in a self-gravitating polytropic cylindrically symmetric and rotating turbulent gas disk.…
Quasi-simultaneous Optical Flux and Polarization Variability of the Binary Super Massive Black Hole Blazar OJ 287 from 2015 to 2023: Detection of an Anticorrelation in Flux and Polarization Variability
Alok C. Gupta, Pankaj Kushwaha, Mauri J. Valtonen +25
We study the optical flux and polarization variability of the binary black hole blazar OJ 287 using quasi-simultaneous observations from 2015 to 2023 carried out using telescopes i…
Toward More Realistic Mass Functions For Ultradense Dark Matter Halos
Saeed Fakhry, Marzieh Farhang, Antonino Del Popolo
Ultradense dark matter halos (UDMHs) are high concentrations of dark matter, assumed to have formed deep in the radiation-dominated era from amplified primordial perturbations. In…
Neutron star mass in dark matter clumps
Maksym Deliyergiyev, Antonino Del Popolo, Morgan Le Delliou
This paper investigates a hypothesis proposed in previous research relating neutron star (NS) mass and its dark matter (DM) accumulation. As DM accumulates, NS mass decreases, pred…
Investigating the origin of optical flares from the TeV blazar S4 0954+65
Ashwani Pandey, Rumen Bachev, Bozena Czerny +4
Aims. We aim to investigate the extreme variability properties of the TeV blazar S4 0954+65 using optical photometric and polarisation observations carried out between 2017 and 202…
Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES~2344+514
H. Abe, S. Abe, V. A. Acciari +232
The BL Lac 1ES 2344+514 is known for temporary extreme properties (e.g., a shift of the synchrotron SED peak energy above 1keV). While those extreme states were so fa…
Empirical Contrast Model for High-Contrast Imaging -- A VLT/SPHERE Case Study
Benjamin Courtney-Barre, Robert De Rosa, Rosita Kokotanekova +4
The ability to accurately predict the contrast achieved from high contrast imagers is important for efficient scheduling and quality control measures in modern observatories. We ai…
Forecasting Solar Energetic Proton Integral Fluxes with Bi-Directional Long Short-Term Memory Neural Networks
Mohamed Nedal, Kamen Kozarev, Nestor Arsenov +1
Solar energetic particles are mainly protons and originate from the Sun during solar flares or coronal shock waves. Forecasting the Solar Energetic Protons (SEP) flux is critical f…
Transient and asymmetric dust structures in the TeV-bright nova RS Oph revealed by spectropolarimetry
Y. Nikolov, G. J. M. Luna, K. A. Stoyanov +4
A long-standing question related to nova eruptions is how these eruptions can lead to the formation of dust despite the ostensibly inhospitable environment for dust within the hot,…
Symbiotic star T CrB as an extreme SU UMa type dwarf nova
Krystian Ilkiewicz, Joanna Mikolajewska, Kiril A. Stoyanov
T CrB is a symbiotic recurrent nova that exhibits quiescent and active phases between its classical nova eruptions. The statistical properties of these active phases have been poor…
Study of the long-term photometric variability of eight PMS stars in the young open cluster Trumpler 37
Sunay Ibryamov, Gabriela Zidarova, Evgeni Semkov +1
This paper reports results from our long-term photometric CCD observations of eight pre-main-sequence stars collected from June 2008 to October 2022. These stars are l…
Surface magnetism in the pulsating RV Tauri star R Scuti
Stefan Georgiev, Agnès Lèbre, Eric Josselin +3
We present the surface magnetic field conditions of the brightest pulsating RV Tauri star, R Sct. Our investigation is based on the longest spectropolarimetric survey ever performe…
Intra-night optical flux and polarization variability of BL~Lacertae during its 2020 2021 high state
Rumen Bachev, Tushar Tripathi, Alok C. Gupta +15
In this work, we report the presence of rapid intra-night optical variations in both -- flux and polarization of the blazar BL Lacertae during its unprecedented 2020--2021 high sta…
The `blazar sequence' in TeV band
Zhihao Ouyang, Hubing Xiao, Jianzhen Chen +7
The `blazar sequence' has been proposed for more than 20 years, yet its nature is still unclear. In this work, for the first time, we expand this topic to the TeV band by using a s…
Analysis of the intra-night variability of BL Lacertae during its August 2020 flare
Aditi Agarwal, B. Mihov, Vipul Agrawal +7
We present an analysis of the photometry of the blazar BL Lacertae on diverse timescales from mid-July to mid-September 2020. We have used 11 different optical telescopes ar…
The ESO's Extremely Large Telescope Working Groups
Paolo Padovani, Michele Cirasuolo, Remco van der Burg +82
Since 2005 ESO has been working with its community and industry to develop an extremely large optical/infrared telescope. ESO's Extremely Large Telescope, or ELT for short, is a re…
Assessing the spectral characteristics of band splitting type II radio bursts observed by CALLISTO spectrometers
F. N. Minta, S. Nozawa, K. Kozarev +2
Metric type II radio bursts are usually early indicators of CME-driven shocks and other space weather phenomena in the solar corona. This paper presents a detailed investigation of…
Characterizing the nucleus of comet 162P/Siding Spring using ground-based photometry
Abbie Donaldson, Rosita Kokotanekova, Agata Rożek +5
Comet 162P/Siding Spring is a large Jupiter-family comet with extensive archival lightcurve data. We report new r-band nucleus lightcurves for this comet, acquired in 2018, 2021 an…
Optical spectroscopy of Be stars: peak separation of Balmer emission lines
R. K. Zamanov, K. A. Stoyanov, S. Y. Stefanov +2
The Be stars display variable optical emission lines originating in the circumstellar disc. Here we analyse high resolution spectroscopic observations of Be stars and the distance…
The optical behaviour of BL Lacertae at its maximum brightness levels: a blend of geometry and energetics
C. M. Raiteri, M. Villata, S. G. Jorstad +13
In 2021 BL Lacertae underwent an extraordinary activity phase, which was intensively followed by the Whole Earth Blazar Telescope (WEBT) Collaboration. We present the WEBT optical…
RFI Flagging in Solar and Space Weather Low Frequency Radio Observations
Peijin Zhang, André R. Offringa, Pietro Zucca +2
Radio spectroscopy provides a unique inspection perspective for solar and space weather research, which can reveal the plasma and energetic electron information in the solar corona…
A 2:1 Mean-Motion Resonance Super-Jovian pair revealed by TESS, FEROS, and HARPS
Vladimir Bozhilov, Desislava Antonova, Melissa J. Hobson +24
We report the discovery of a super-Jovian 2:1 mean-motion resonance (MMR) pair around the G-type star TIC 279401253, whose dynamical architecture is a prospective benchmark for pla…
Solar radio bursts observations by Egypt- Alexandria CALLISTO spectrometer: First results
F. N. Minta, S. Nozawa, K. Kozarev +2
The newly installed CALLISTO spectrometer, hosted by the Department of Space Environment, Institute of Basic and Applied Sciences- EJUST, commenced operation on August 14, 2021. Th…
Tilted discs in six poorly studied cataclysmic variables
Stefan Y. Stefanov, Atanas K. Stefanov
In this work, we search for negative superhumps (nSHs) in poorly studied cataclysmic variables using TESS data. We find three eclipsing binaries with nSH signatures: HBHA 4204-09,…