A5017401133- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Astronomical and nuclear sciences
- Gamma-ray bursts and supernovae
- Calibration and Measurement Techniques
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Atmospheric Ozone and Climate
- High-pressure geophysics and materials
- Galaxies: Formation, Evolution, Phenomena
- History and Developments in Astronomy
Vilnius University
2016-2022
The last decade has seen a revolution in our knowledge of the Galaxy thanks to Gaia and asteroseismic space missions ground-based spectroscopic surveys. To complete this picture, it is necessary map ages its stellar populations. During recent years, dependence on time abundance ratios involving slow (s) neutron-capture $\alpha$ elements (called chemical-clocks) been used provide estimates ages, usually limited volume close Sun. We aim analyse relations chemical clocks Galactic disc extending...
Several works have found an increase of the abundances s-process neutron-capture elements in youngest Galactic stellar populations, giving important constraints to and evolution. We aim trace abundance patterns time-evolution five first peak, Y Zr, second Ba, La Ce using Gaia-ESO idr5 results. From UVES spectra cluster member stars, we determined average composition clusters with ages >0.1 Gyr. derived statistical distances field separated them thin thick disc populations. studied time...
The GES survey using FLAMES at the VLT has obtained high-resolution UVES spectra for a large number of giant stars, allowing determination abundances key chemical elements C and N their surface. surface these species are well-known to change in stars during evolution on red branch after first dredge-up episod, as result extra-mixing phenomena. We investigate effects thermohaline mixing comparison between [C/N] determinations with simulations observed fields model stellar population...
In the era of large high-resolution spectroscopic surveys, high-quality spectra can contribute to our understanding Galactic chemical evolution, providing abundances belonging different nucleosynthesis channels, and also constraints stellar age. Some abundance ratios have been proven be excellent indicators ages. We aim at an empirical relationship between ages [C/N] using, as calibrators, open star clusters observed by both Gaia-ESO APOGEE surveys. use parameters from field cluster stars....
The aim of this work is to determine abundances neutron-capture elements for thin- and thick-disc F, G, K stars in several sky fields near the north ecliptic pole compare results with Galactic chemical evolution models, explore elemental gradients according stellar ages, mean galactocentric distances, maximum heights above plane. observational data were obtained 1.65m telescope at Moletai Astronomical Observatory a fibre-fed high-resolution spectrograph. Elemental determined using...
Abundances of lithium, carbon, and oxygen have been derived using spectral synthesis for a sample 249 bright F, G, K Northern Hemisphere dwarf stars from the high-resolution spectra acquired with VUES spectrograph at Moletai Astronomical Observatory Vilnius University. The metallicities, effective temperatures, ages between -0.7 0.4 dex; 5000 6900 K; 1 12 Gyr, accordingly. We confirm so far unexplained lithium abundance decrease supersolar metallicities - $A$(Li) in our stars, which drop by...
Context . The abundance ratio N/O is a useful tool to study the interplay of galactic processes, for example star formation efficiency, timescale infall, and outflow loading factor. Aims We aim trace log(N/O) versus [Fe/H] in Milky Way compare this with set chemical evolution models understand role outflow, efficiency building up Galactic disc. Methods used abundances from IDR2-3, IDR4, IDR5 data releases Gaia -ESO Survey both field open cluster stars. determined membership average...
Abstract In fulfilling the aims of planetary and asteroseismic research missions, such as that NASA Transiting Exoplanet Survey Satellite (TESS) space telescope, accurate stellar atmospheric parameters a detailed chemical composition are required inputs. We have observed high-resolution spectra for all 848 bright ( V < 8 mag) stars cooler than F5 spectral class in area up to 12 deg surrounding northern TESS continuous viewing zone uniformly determined main parameters, ages, orbital...
High-resolution spectral analysis is performed for the first time in evolved stars of two young open clusters: NGC 4609 and 5316, about 80 100 Myr age, respectively, turn-off masses above 5 M⊙. Stellar evolution models predict an extra-mixing event stars, which follows dredge-up happens later on red giant branch. However, it still not understood how this process affects different masses. In study, we determine abundances mixing sensitive elements carbon nitrogen, isotope 12C/13C ratios, as...
Accurate atmospheric parameters and chemical composition of stars play a vital role in characterizing physical exoplanetary systems understanding their formation. A full asteroseismic characterization star is also possible if its main are known. The NASA Transiting Exoplanet Survey Satellite (TESS) space telescope will very important searching exoplanets around bright stellar variability research. We have observed all 302 (V < 8 mag) cooler than F5 spectral class the northern TESS continuous...
New space missions (e.g., NASA-TESS and ESA-PLATO) will perform an in-depth analysis of bright stars in large fields the celestial sphere searching for extraterrestrial planets investigating their host-stars. Asteroseismic observations search exoplanet-hosting with solar-like oscillations. In order to achieve all goals, a full characterization stellar objects is important. However, accurate atmospheric parameters are available less than 30% dwarf solar neighborhood. this study we observed...
Eclipsing binary stars allow derivation of accurate and precise masses radii. When they reside in star clusters, properties even higher precision, along with additional information, can be extracted. Asteroseismology solar-like oscillations offers similar possibilities for single stars. We improve the previously established Hyades eclipsing HD27130 re-assess asteroseismic giant $\epsilon$ Tau. The physical these members are then used to constrain helium content age cluster. New multi-colour...
Context. NGC 1851 is one of several globular clusters for which multiple stellar populations the subgiant branch have been clearly identified and a difference in metallicity detected. A crucial piece information on formation history this cluster can be provided by sum (C+N+O) abundances. However, these values lacked general consensus thus far. The separation based age and/or abundance differences. Aims. Our main aim was to determine carbon, nitrogen, oxygen abundances evolved giants order...
Context: Homogeneous investigations of red giant stars in open clusters contribute to studies internal evolutionary mixing processes inside stars, which are reflected abundances mixing-sensitive chemical elements like carbon, nitrogen, and sodium, while alpha- neutron-capture element useful tracing the Galactic evolution. Aims: The main aim this study is a comprehensive analysis cluster IC 4756, including determinations 12C/13C C/N abundance ratios, comparisons results with theoretical...
The Hipparcos catalog contains stars suspected to be δ Scuti variables for which extensive ground-based observations and characterization of variability are necessary. Our aim was characterize 13 candidates type stars. We obtained 24 215 CCD images analyzed stellar light curves using the Period04 program. Twelve candidate have been characterized as pulsating with frequencies intrinsic stars: HIP 2923, 5526, 5659, 11090, 17585, 74155, 101473, 106219, 107786, 113487, 115093, 115856. Five them...
Abstract The ESA-PLATO 2.0 mission will perform an in-depth analysis of the large part sky-sphere searching for extraterrestrial telluric-like planets. At Molėtai Astronomical Observatory Vilnius University, we started a spectroscopic and photometric survey northern sky fields that potentially be targeted by PLATO mission. We aim to contribute in developing input catalogue delivering long-duration stellar variability information full characterization brightest targets. First results this are...
Abstract Asymptotic giant branch stars play an important role in enriching galaxies by s-process elements. Recent studies have shown that their producing elements the Galactic disc was underestimated and should be reconsidered. Based on high-resolution spectra we determined abundances of neutron-capture a sample 310 located field open clusters investigated elemental enrichment patterns according to age mean galactocentric distances.
Abstract High-resolution spectra for all bright ( mag) and cooler than F5 spectral class dwarf stars were observed in two fields with radii of 20 degrees (centered at (2000) = 161.03º 86.60º 265.08º 39.58º) towards the northern ecliptic pole. They coincide preliminary ESA PLATO which also will be targeted by NASA TESS mission. We use high-resolution obtained VUES spectrograph mounted on 1.65 m telescope Moletai Astronomical Observatory Institute Theoretical Physics Astronomy, Vilnius...
Abstract A spread of lifebuilding elements, such as carbon, nitrogen, and oxygen in the Galactic discs is yet not well investigated. In this study, we use spectra from UVES spectrograph (Gaia-ESO survey ) VUES spectograph (SPFOT-PLATO survey) determine abundances FGK stars using same technique. For some our target Gaia space observatory has already presented accurate distances, thus overview first results radial vertical CNO abundance distributions thin thick disc populations.