E. Paraskeva
A5089147959- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Calibration and Measurement Techniques
- Astronomical Observations and Instrumentation
- Advanced Research in Systems and Signal Processing
- Advanced Power Generation Technologies
- Color Science and Applications
- Astro and Planetary Science
- Radiative Heat Transfer Studies
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Neutrino Physics Research
- Spectroscopy and Laser Applications
- Scientific Computing and Data Management
- Photocathodes and Microchannel Plates
- Pulsars and Gravitational Waves Research
- Laser Design and Applications
National Observatory of Athens
2019-2023
University of California, Davis
2023
Nordic Optical Telescope
2022
National Technical University of Athens
2022
National and Kapodistrian University of Athens
2019-2022
Aarhus University
2022
Abstract We present the optical spectroscopic evolution of SN 2023ixf seen in subnight cadence spectra from 1.18 to 15 days after explosion. identify high-ionization emission features, signatures interaction with material surrounding progenitor star, that fade over first 7 days, rapid between observed within same night. compare lines and their relative strength those other supernovae early interaction, finding a close match 2020pni 2017ahn spectrum 2014G at later epochs. To physically...
We present high-cadence optical, ultraviolet (UV), and near-infrared data of the nearby ($D\approx23$ Mpc) Type II supernova (SN) 2021yja. Many SNe show signs interaction with circumstellar material (CSM) during first few days after explosion, implying that their red supergiant (RSG) progenitors experience episodic or eruptive mass loss. However, because it is difficult to discover early, diversity CSM configurations in RSGs has not been fully mapped. SN 2021yja, detected within...
We investigate the spectroscopic characteristics of intermediate-luminosity Red Transients (ILRTs), a class elusive objects with peak luminosity between that classical novae and standard supernovae. Our goal is to provide stepping stone in path unveiling physical origin these events based on analysis collected datasets. present extensive optical near-infrared (NIR) monitoring four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, 2019ahd 2019udc. First we focus evolution most prominent spectral...
We investigate the photometric characteristics of a sample intermediate-luminosity red transients (ILRTs), class elusive objects with peak luminosity between that classical novae and standard supernovae. Our goal is to provide stepping stone in path reveal physical origin such events, thanks analysis datasets collected. present multi-wavelength follow-up four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, 2019ahd, 2019udc. Through modelling their spectral energy distribution bolometric light...
We present a spectroscopic analysis of Type I superluminous supernova (SLSN-I), SN 2018bsz. While it closely resembles SLSNe-I, the multi-component H$\alpha$ line appearing at $\sim30$ d post-maximum is most atypical. The characterised by two emission components, one $+3000$ km/s and second $-7500$ km/s, with third, near-zero velocity component after delay. blue central components can be described Gaussian profiles intermediate width, but red significantly broader Lorentzian. evolves towards...
Thanks to the advent of large-scale optical surveys, a diverse set flares from nuclear regions galaxies has recently been discovered. These include disruption stars by supermassive black holes at centers - transients known as tidal events (TDEs). Active galactic nuclei (AGN) can show extreme changes in brightness and emission line intensities, often referred changing-look AGN (CLAGN). Given physical observational similarities, interpretation distinction CLAGN or TDEs remains difficult. One...
Abstract We present photometric and spectroscopic observations of SN 2023fyq, a Type Ibn supernova (SN) in the nearby galaxy NGC 4388 ( D ≃ 18 Mpc). In addition, we trace 3 yr long precursor emission at position 2023fyq using data from DLT40, ATLAS, Zwicky Transient Facility, ASAS-SN, Swift, amateur astronomer Koichi Itagaki. The double-peaked postexplosion light curve reaches luminosity ∼10 43 erg s −1 . strong intermediate-width He lines observed nebular spectrum imply interaction is still...
We present the optical spectroscopic evolution of SN~2023ixf seen in sub-night cadence spectra from 1.18 to 14 days after explosion. identify high-ionization emission features, signatures interaction with material surrounding progenitor star, that fade over first 7 days, rapid between observed within same night. compare lines and their relative strength those other supernovae early interaction, finding a close match SN~2020pni SN~2017ahn spectrum SN~2014G at later epochs. To physically...
ABSTRACT We present extensive ultraviolet (UV) and optical photometric spectroscopic follow-up of supernova (SN) 2021gno by the ‘Precision Observations Infant Supernova Explosions’ (POISE) project, starting less than 2 d after explosion. Given its intermediate luminosity, fast evolution, quick transition to nebular phase with spectra dominated [Ca ii] lines, SN belongs small family Calcium-rich transients. Moreover, it shows double-peaked light curves, a phenomenon shared only four other...
ABSTRACT The ultraviolet (UV) and near-infrared (NIR) photometric optical spectroscopic observations of SN 2020acat covering ∼250 d after explosion are presented here. Using the fast rising observations, spanning from UV to NIR wavelengths, a pseudo-bolometric light curve was constructed compared several other well-observed Type IIb supernovae (SNe IIb). displayed very short rise time reaching peak luminosity $\mathrm{{\rm Log}_{10}}(L) = 42.49 \pm 0.17 \, \mathrm{erg s^{-1}}$ in only ∼14.6...
Aims. Over its lifetime and despite not being a survey telescope, the Hubble Space Telescope (HST) has obtained multi-epoch observations by multiple, diverse observing programs, providing opportunity for comprehensive variability search aiming to uncover new variables. We have therefore undertaken task of creating catalog variable sources based on archival HST photometry. In particular, we used version 3 Source Catalog (HSC), which relies publicly available images with WFPC2, ACS, WFC3...
SN 2018hti was a very nearby (z=0.0614) superluminous supernova with an exceedingly bright absolute magnitude of -21.7 mag in r-band at maximum. The densely sampled pre-maximum light curves show slow luminosity evolution and constrain the rise time to ~50 rest-frame days. We fitted synthetic photometry infer physical parameters explosion for both magnetar CSM-interaction scenarios. conclude that one two mechanisms could be powering 2018hti; interaction ~10 Msun circumstellar material or...
We present high-cadence optical, ultraviolet (UV), and near-infrared data of the nearby ($D\approx23$ Mpc) Type II supernova (SN) 2021yja. Many SNe show signs interaction with circumstellar material (CSM) during first few days after explosion, implying that their red supergiant (RSG) progenitors experience episodic or eruptive mass loss. However, because it is difficult to discover early, diversity CSM configurations in RSGs has not been fully mapped. SN 2021yja, detected within...
We investigate the photometric characteristics of a sample Intermediate Luminosity Red Transients (ILRTs), class elusive objects with peak luminosity between that classical novae and standard supernovae. present multi-wavelength follow-up four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, 2019ahd 2019udc. Through analysis modelling their spectral energy distribution bolometric light curves we infer physical parameters associated these transients. All display single peaked curve which ends in...
Abstract We investigate the thermal emission and extinction from dust associated with nearby superluminous supernova (SLSN) 2018bsz. Our dataset has daily cadence simultaneous optical near-infrared coverage up to ~ 100 days, together late time (+1.7 yr) MIR observations. At 230 days after light curve peak SN is not detected in optical, but shows a surprisingly strong excess, r - J > 3 mag K s 5 mag. The evolution of infrared enables us if mid-infrared newly formed inside ejecta,...
We present extensive ultraviolet (UV) and optical photometric spectroscopic follow-up of supernova (SN)~2021gno by the "Precision Observations Infant Supernova Explosions" (POISE) project, starting less than two days after explosion. Given its intermediate luminosity, fast evolution, quick transition to nebular phase with spectra dominated [Ca~II] lines, SN~2021gno belongs small family Calcium-rich transients. Moreover, it shows double-peaked light curves, a phenomenon shared only four other...
Rapid variability before and near the maximum brightness of supernovae has potential to provide a better understanding nearly every aspect supernovae, from physics explosion up their progenitors circumstellar environment. Thanks modern time-domain optical surveys, which are discovering in early stage evolution, we have unique opportunity capture intraday behavior maximum. We present high-cadence photometric monitoring (on order seconds-minutes) light curves three Type Ia two II SNe over...
Abstract Tidal disruption events (TDEs) are bursts of electromagnetic energy released when supermassive black holes at the center galaxies violently disrupt stars that pass too close. TDEs provide a new window to study accretion onto holes; in some cases, this leads launching relativistic jet, but necessary conditions not fully understood. Here, we report optical discovery AT2022cmc, rapidly fading source located redshift z=1.19325. Observations bright counterpart other wavelengths,...