A5014159288- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Atmospheric Ozone and Climate
- Pulsars and Gravitational Waves Research
- Nuclear Physics and Applications
- Astronomical and nuclear sciences
- Radiopharmaceutical Chemistry and Applications
- Crystallography and Radiation Phenomena
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
- History and Developments in Astronomy
- Earthquake Detection and Analysis
- Quantum Electrodynamics and Casimir Effect
- Thermal Radiation and Cooling Technologies
- Photonic Crystals and Applications
- Relativity and Gravitational Theory
- Chemical Synthesis and Characterization
- Advanced X-ray Imaging Techniques
A. Alikhanyan National Laboratory
2008-2024
Byurakan Astrophysical Observatory
2009-2019
National Academy of Sciences of Armenia
2018
Isaac Newton Institute
2008-2013
Yerevan State University
2011-2012
Compositions of rocky exoplanets The interior compositions small cannot be observed directly but are expected to relate the composition host star. Adibekyan et al . analyzed a sample exoplanets, inferring planets’ iron fractions by combining their masses and radii with an structure model. stars were calculated from stellar elemental abundances. two fractions, that planets stars, correlate each other, slope is steeper than 1, indicating planet formation processes modify planets. —KTS
(Abridged) We analyze chemical and kinematical properties of about 850 FGK solar neighborhood long-lived dwarfs observed with the HARPS high-resolution spectrograph. The stars in sample have logg > 4 dex, 5000 < Teff 6500 K, -1.39 [Fe/H] 0.55 dex. apply a purely analysis approach based on [alpha/Fe] vs. plot to separate Galactic stellar populations into thin disk, thick disk high-alpha metal-rich (hamr). Our shows negative gradient rotational velocity (-17 km s^-1 dex^-1), steep...
Recent studies showed that at low metallicities Doppler-detected planet-hosting stars have preferably high alpha-content and belong to the thick disk. We used reconnaissance spectra of 87 Kepler planet candidates data available from HARPS search survey explore this phenomena. Using traditional spectroscopic abundance analysis methods we derived Ti, Ca, Cr abundances for stars. In metallicity region -0.65 < [Fe/H] -0.3 dex fraction Ti-enhanced thick-disk harboring is 12.3 +/- 4.1 % their...
The main goal of this work is to explore which elements carry the most information about birth origin stars and as such that are best suited for chemical tagging. We explored different techniques minimize effect outlier value lines in abundances by using Ni derived 1111 FGK type stars.We evaluated how limited number spectral can affect final abundance. Then we were able make an efficient even footing comparison [X/Fe] scatter between have observable studied spectra. found way calculating...
<i>Aims. <i/>With the goal of providing constraints on nature progenitors core-collapse (CC) supernovae (SNe), we compare their radial distribution within spiral host galaxies with distributions stars and ionized gas in disks.<i>Methods. <i/>SNe positions are taken from Asiago catalog for a well-defined sample 224 SNe 204 galaxies. The SN distances estimated deprojected separations galaxy nuclei, normalized both to 25th blue-band isophotal radius (for first time) statistically-estimated disk...
(Abridged) In this first paper of a series, we report the creation large and well-defined database that combines extensive new measurements literature search 3876 supernovae (SNe) their 3679 host galaxies located in sky area covered by Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). This should be much larger than previous ones, contain homogenous set global parameters SN hosts, including morphological classifications measures nuclear activity. The apparent magnitudes, diameters (D25),...
In this paper we present a new catalogue of Chemically Peculiar (CP) stars obtained by compiling publications in which abundances metals are provided. Our includes 428 for the data were through spectroscopic observations. Most them (416) AmFm, HgMn and ApBp stars. We have used compilation to proceed statistical overview abundance anomalies versus physical parameters The Spearman's rank correlation test has been applied, significant number correlations peculiarities with respect effective...
Context . The determination of planetary densities from the masses derived with radial velocity (RV) and transit-timing variation (TTV) methods reveals discrepancies. Specifically, planets detected through RV exhibit higher than those TTV, even though their radii are similar. Understanding origins these discrepancies is crucial timely, especially upcoming ground- space-based missions dedicated to exoplanet research. Aims We explored possibility that discrepant mass/densities in TTV...
We present an analysis of the impact bars and bulges on radial distributions different types supernovae (SNe) in stellar discs host galaxies with various morphologies. use a well-defined sample 500 nearby (≤100 Mpc) SNe their low-inclined (i ≤ 60°) morphologically non-disturbed S0–Sm from Sloan Digital Sky Survey. find that Sa–Sm galaxies, all core-collapse (CC) vast majority Ia belong to disc, rather than bulge component. The distribution S0–S0/a is inconsistent hosts, which probably due...
During the past decade, several studies reported a correlation between chemical abundances of stars and condensation temperature (also known as Tc trend). However, real astrophysical nature this is still debated. The main goal work to explore possible dependence trend on stellar Galactocentric distances, Rmean. We used high-quality spectra about 40 observed with HARPS UVES spectrographs derive precise parameters, abundances, ages. A differential line-by-line analysis was applied achieve...
The main goal of this work is to study element ratios that are important for the formation planets different masses. We potential correlations between existence planetary companions and relative elemental abundances their host stars. use a large sample FGK-type dwarf stars which precise Mg, Si, Fe have been derived using HARPS high-resolution high-quality data. A first analysis data suggests low-mass planet show higher [Mg/Si] ratios, while giant hosts present lower than field However, we...
Several studies have reported a correlation between the chemical abundances of stars and condensation temperature (known as Tc trend). Very recently, strong trend was for $ζ$ Reticuli binary system, which consists two solar analogs. The observed in $ζ^2$ Ret relative to its companion explained by presence debris disk around Ret. Our goal is re-evaluate variability system understand impact on star. We used very high-quality spectra retrieved from HARPS archive derive precise stellar...
Aims. It is widely accepted that the progenitors of core collapse SNe are young massive stars and therefore their host galaxies mostly spiral or irregular dominated by a stellar population. Surprisingly, among morphologically classified hosts SNe, we find 22 cases where has been as an Elliptical S0 galaxy.
We present an analysis of the relative frequencies different supernova (SN) types in spirals with various morphologies and barred or unbarred galaxies. use a well-defined homogeneous sample spiral host galaxies 692 SNe from Sloan Digital Sky Survey stages galaxy–galaxy interaction activity classes nucleus. propose that underlying mechanisms shaping number ratios can be interpreted within framework interaction-induced star formation, addition to known relations between stellar populations....
Using a sample of 215 supernovae (SNe), we analyze their positions relative to the spiral arms host galaxies, distinguishing grand-design (GD) spirals from non-GD (NGD) galaxies. We find that: (1) in GD an offset exists between Ia and core-collapse (CC) SNe peaks arms, while NGD galaxies show no such shifts; (2) CC are correlated with radial distance galaxy nucleus. Inside (outside) corotation radius, found closer inner (outer) edge. No correlation is observed for nor either class; (3) Ibc...
ABSTRACT We present an analysis of the light curve (LC) decline rates (Δm15) 407 normal and peculiar supernovae (SNe) Ia global parameters their host galaxies. As previously known, there is a significant correlation between Δm15 SNe ages (morphologies, colours, masses) hosts. On average, those that are in galaxies from Red Sequence (early-type, massive, old hosts) have faster declining LCs comparison with Blue Cloud (late-type, less younger colour–mass diagram. The observed correlations...
We present an analysis of the height distributions different types supernovae (SNe) from plane their host galaxies. use a well-defined sample 102 nearby SNe appeared inside high-inclined (i > 85 deg), morphologically non-disturbed S0-Sd galaxies Sloan Digital Sky Survey. For first time, we show that in all subsamples spirals, vertical distribution core-collapse (CC) is about twice closer to disc than Ia. In Sb-Sc hosts, exponential scale CC consistent with those younger stellar population...
Abstract To enlarge our data base of chemically peculiar stars, we compiled published concerning the He-weak and He-rich stars observed by high-resolution spectroscopy techniques during last decades. Twenty 28 have been added to base. We also distinguished roAp from previously identified as Ap stars. deepen knowledge on statistical overview abundance anomalies versus physical parameters compared with previous compilations. applied tests found interesting correlations for effective...
We present an analysis of the galactocentric distributions "normal" and peculiar "91bg-like" subclasses 109 supernovae (SNe) Ia, study global parameters their elliptical hosts. The SN are consistent with each other, radial light distribution host stellar populations, when excluding bias against central SNe. Among parameters, only u-r colours ages inconsistent significantly between ellipticals different Ia subclasses: normal hosts on average bluer/younger than those 91bg-like In colour-mass...
Context . The composition of rocky planets is strongly driven by the primordial materials in protoplanetary disk, which can be inferred from abundances host star. Understanding this compositional link crucial for characterizing exoplanets. Aims We aim to investigate relationship between compositions low-mass and their stars. Methods determined stars using high-precision present-day stellar evolutionary models. These were then input into a stoichiometric model estimate planet-building blocks....
Finding solar siblings, that is, stars formed in the same cluster as Sun, will yield information about conditions at Sun's birthplace. We search for sibling candidates AMBRE, very large spectra database of vicinity stars. Since ages and chemical abundances siblings are similar to those we carried out a chemistry- age-based candidates. used high-resolution derive precise stellar parameters these spectroscopic together with Gaia DR2 astrometric data isochronal ages. were also study kinematics...