A5001898919- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Matrix Theory and Algorithms
- Parallel Computing and Optimization Techniques
- Ocular and Laser Science Research
- Advanced Optical Sensing Technologies
- Numerical Methods and Algorithms
Czech Academy of Sciences, Astronomical Institute
2018-2025
National Observatory of Athens
2013-2018
National and Kapodistrian University of Athens
2010-2017
Abstract In this Letter, we shed light on the evolutionary phase of HD 144812, a Galactic yellow supergiant showing infrared excess that is typically expected for evolved stars undergoing enhanced mass-loss activity. We present high-resolution spectroscopy star in H − and K −band acquired with GRating INfrared Spectrometer (IGRINS) further explore multi-band imaging wider field view from ultraviolet to radio regime. The IGRINS data reveal several lines hydrogen series iron double-peaked...
In this Letter, we shed light on the evolutionary phase of HD 144812, a Galactic yellow supergiant showing infrared excess that is typically expected for evolved stars undergoing enhanced mass-loss activity. We present high-resolution spectroscopy star in $H-$ and $K-$band acquired with GRating INfrared Spectrometer (IGRINS) further explore multi-band imaging wider field view from ultraviolet to radio regime. The IGRINS data reveal several lines hydrogen series iron double-peaked emission...
Blue supergiants (BSGs) span phases between the main sequence and late stages of massive stars, which makes them valuable for assessing physics that drives stars across diverse evolutionary channels. By exploring correlations parameters BSGs their variability properties, we aim to improve constraints on models evolved star structure post-main-sequence evolution. We conducted a study 41 with known spectroscopic in Galaxy using high-precision photometry from Transiting Exoplanet Survey...
We present a variability study of 4646 massive stars in the Small Magellanic Cloud (SMC) with known spectral types from catalog Bonanos et al. (2010) using light curves OGLE-III database. The goal is to exploit time domain information available through gain insight into processes that govern evolution stars. This survey larger than any previous by factor 7. find 60% our sample (2766 stars) show no significant and 40% (1880 exhibit distributed as follows: 807 display low-amplitude stochastic...
The massive stars that survive the phase of red supergiants (RSGs) spend rest their life in extremity. Their unstable atmospheres facilitate formation and episodic ejection shells alter stellar appearance surroundings. In present study, we revise evolutionary state eight hypergiants Magellanic Clouds, four early-A type FG type, complement short list eruptive post-RSGs termed as yellow (YHGs). We refine outdated temperatures luminosities by means high-resolution spectroscopy with FEROS....
We present a one-dimensional radiation-hydrodynamic model of spherically symmetric cloud evolving under the influence self-gravity and feedback from star cluster forming in its centre. On one hand, is simple due to 1D geometry, on other includes ionising radiation, stellar winds radiation pressure acting gas dust. The formed flowing into centre parameters are determined evolution models history. compared semi-analytic code WARPFIELD implementing similar physical processes exploring scenario...
The advanced stages of several high-mass stars are characterized by episodic mass loss shed during phases instability. Key for assigning these a proper evolutionary state is to assess the composition and geometry their ejecta alongside stellar properties. We selected five hot LBV candidates in M33 refine classification, investigate circumstellar environments explore Being accessible targets near-infrared, we conducted medium-resolution spectroscopy with GNIRS/GEMINI $K-$band molecular...
The evolution of massive stars surviving the red supergiant (RSG) stage remains unexplored due to rarity such objects. yellow hypergiants (YHGs) appear be warm counterparts post-RSG classes located near Humphreys-Davidson upper luminosity limit, which are characterized by atmospheric instability and high mass-loss rates. We aim increase number YHGs in M33 thus contribute a better understanding pre-supernova stars. Optical spectroscopy five dust-enshrouded YSGs selected from mid-IR criteria...
We present a study of the properties O-type, massive eclipsing binary 2MASS J13130841-6239275 located in outskirts Danks 2 cluster G305 star-forming complex, using near-infrared spectroscopy from VLT/ISAAC. derive masses and radii to be 24.5 ± 0.9 M⊙ 9.2 0.1 R⊙ for primary 21.7 0.8 8.7 secondary component. In addition, we evaluate sensitivity our parameters choice spectral features used determine radial velocities. Both components appear main-sequence O6.5−O7 type stars at an age ~5 Myr,...
We analyzed the massive star population of Virgo Cluster galaxy NGC 4535 using archival Hubble Space Telescope Wide Field Planetary Camera 2 images in filters F555W and F814W, equivalent to Johnson V Kron-Cousins I. performed high precision point spread function fitting photometry 24353 sources including 3762 candidate blue supergiants, 841 yellow supergiants 370 red supergiants. estimated ratio as a decreasing galactocentric radius. Using Modules for Experiments Stellar Astrophysics...
Studies of the massive star population in galaxies beyond Local Group are key to understanding link between their numbers and modes formation different environments. We present analysis NGC 1326A, 1425, 4548 using archival images obtained with Hubble Space Telescope Wide Field Planetary Camera 2 F555W F814W filters. Through high-precision point spread function fitting photometry for all sources three fields, we identified 7640 candidate blue supergiants, 2314 yellow 4270 red supergiants....
Massive stars expel large amounts of mass during their late evolutionary phases. We aim to unveil the physical conditions within warm molecular environments B[e] supergiants (B[e]SGs) and yellow hypergiants (YHGs), which are known be embedded in circumstellar shells disks. present K-band spectra two B[e]SGs from Large Magellanic Cloud four Galactic YHGs. The CO band emission detected LHA 120-S 12 134 suggests that these surrounded by stable rotating rings. YHGs display a rather diverse...
Abstract We present the first systematic study of 4646 spectroscopically confirmed early-type massive stars in Small Magellanic Cloud (SMC), using variability as a tool to confine physics OB-type stars. report discovery ∼100 eclipsing systems which are useful for accurate determination fundamental parameters and we evaluate frequency multiplicity. In addition, explore occurrence Oe/Be phenomenon provide large number candidate non-radial pulsators, can be further studied via asteroseismology....
We present a one-dimensional radiation-hydrodynamic model of spherically symmetric cloud evolving under the influence self-gravity and feedback from star cluster forming in its centre. On one hand, is simple due to 1D geometry, on other includes ionising radiation, stellar winds radiation pressure acting gas dust. The formed flowing into centre parameters are determined evolution models history. compared semi-analytic code WARPFIELD implementing similar physical processes exploring scenario...
Symbiotic stars are interacting binary systems composed of an evolved star (generally a late-type red giant) and degenerate or dwarf companion in orbit close enough for mass transfer to occur. Understanding the status is important developing models symbiotic as it affects matter needed activate hot component. Infrared observations have been very useful probing nature systems. This work presents set observed with SOAR/OSIRIS (R∼3000) H-band. We aimed search possible molecular circumstellar...
This paper presents a detailed analysis of the light and radial velocity curves semi-detached eclipsing binary system OGLE-LMC-ECL-09937. The is composed hot, massive luminous primary star late-O spectral type, more evolved, but less secondary, implying an Algol-type that underwent mass transfer episode. We derive masses 21.04 +/- 0.34 M_Sun 7.61 0.09 radii 9.93 0.06 R_Sun 9.18 0.04 R_Sun, for secondary component, respectively, which make it most known with components measured <2% accuracy....