A5059980582- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Historical Studies of Medieval Iberia
- Engineering Applied Research
- Soil Carbon and Nitrogen Dynamics
- Space Exploration and Technology
- Engineering and Information Technology
- Agriculture, Soil, Plant Science
- Calibration and Measurement Techniques
- Geomagnetism and Paleomagnetism Studies
- Solar and Space Plasma Dynamics
- Particle Accelerators and Free-Electron Lasers
- Atmospheric Ozone and Climate
- Ruminant Nutrition and Digestive Physiology
- Bee Products Chemical Analysis
- Milk Quality and Mastitis in Dairy Cows
- Adaptive optics and wavefront sensing
- Structural Analysis of Composite Materials
- Natural Products and Biological Research
Consejo Nacional de Investigaciones Científicas y Técnicas
2009-2025
National University of Río Negro
2019-2025
Centro Científico Tecnológico - San Juan
2021
Instituto de Astrofísica de La Plata
2008-2019
Western University
2017-2018
Global Social Observatory
2010-2014
University of Geneva
2010-2014
Universidad Nacional de La Plata
2009-2011
[abridged] Many topical astrophysical research areas, such as the properties of planet host stars, nature progenitors different types supernovae and gamma ray bursts, evolution galaxies, require complete homogeneous sets stellar models at metallicities in order to be studied during whole cosmic history. We present here a first set for solar metallicity, where effects rotation are accounted way. computed grid 48 evolutionary tracks, both rotating non-rotating, Z=0.014, spanning wide mass...
Aims. We study the impact of a subsolar metallicity on various properties non-rotating and rotating stars, such as surface velocities abundances, lifetimes, evolutionary tracks, scenarios.
B-type stars are known to rotate at various velocities, including very fast rotators near the critical velocity as Be stars. In this paper, we provide stellar models covering mass range between 1.7 15 Msun, which includes typical of stars, Z = 0.014, 0.006, and 0.002 for an extended initial velocities on zero-age main sequence. We used Geneva stellar-evolution code, effects shellular rotation, with a numerical treatment that has been improved so code can precisely track variation in angular...
(abridged) We present a new tool for building synthetic colour-magnitude diagrams of coeval stellar populations. study, from theoretical point view, the impact axial rotation stars on various observed properties single-aged populations: magnitude at turnoff, photometric evolved stars, surface velocities, abundances, and age determination clusters by an isochrone fitting. Stellar models different initial masses, metallicities, zero-age main sequence (ZAMS) rotational velocities are used...
The post main-sequence evolution of massive stars is very sensitive to many parameters the stellar models. Key are mixing processes, metallicity, mass-loss rate and effect a close companion. We study how red supergiant lifetimes, tracks in Hertzsprung-Russel diagram (HRD), positions this pre-supernova progenitor as well structure at that time change for various rates during phase (RSG), two different initial rotation velocities. surface abundances RSGs much more than phase. A RSG has strong...
Context. Even though it is broadly accepted that single Be stars are rapidly rotating surrounded by a flat circumstellar disk, there still debate about how fast these rotate and also the mechanisms involved in angular-momentum mass input disk.
Context. Tides are known to play an important role in binary evolution, leading particular synchronization of axial and orbital rotations mass transfer.
ABSTRACT This study focuses on the open cluster NGC 6834. Despite being well-known, its primary parameters show considerable variation. As an intermediate-age (50–80 million years), it is expected to host a prominent population of B-type stars, including numerous Be stars. Fifteen variable stars have already been identified in vicinity cluster, with four confirmed as through spectroscopic observations. Our spectrophotometric analysis aims better understand general and specific properties...
We review the significant role played by red supergiants (RSGs) in stellar populations, and some challenges questions they raise for theoretical evolution. present how metallicity rotation modify way stars go to part of Hertzsprung-Russell diagram or come back from it, RSGs might keep a trace their main-sequence compare population ratios with observed ones.
We investigate the nature of OGLE 05155332−6925581, one brightest members enigmatic group double periodic variables (DPVs) recently found in Magellanic Clouds. The modelling archival orbital light curves (LCs), along with analysis radial velocities (RVs) suggest that this object is a semidetached binary less massive star transferring matter to more and evolved star, an Algol-like configuration. find evidence for additional variability Hα emission, likely caused by accretion disc around...
The theory of radiation-driven winds succeeded in describing terminal velocities and mass loss rates massive stars. However, for A-type supergiants the standard m-CAK solution predicts values velocity higher than observed values. Based on existence a slow wind fast rotating stars, we explore numerically parameter space flows to search new solutions slowly that could explain origin these discrepancies. We solve 1-D hydrodynamical equation at different stellar latitudes influence ionization's...
The database of intermediate mass rotating stellar models presented in the past years by Geneva Stellar Evolution Group can be used to build synthetic populations that fully account for effects rotation. However, up now we still lacked evolutionary tracks rotate close critical limit during whole MS phase. This occurs because flat internal profile rotation imposed at Zero-Age (ZAMS) is modified action meridional currents immediately after ZAMS, causing surface rotational velocity decrease...
We present medium-resolution K- and L-band spectra of a sample eight Be stars, obtained with Gemini/NIRI. The IR K L bands contain many lines different hydrogen series that are used as diagnosis to the physical conditions in circumstellar environments. make an analysis on optical depths line-forming regions based intensity ratios Pfγ Brα lines, behavior Humphreys' series, fluxes Brγ lines. All our targets show spectroscopic photometric long-term variability; thus, time-resolved spectroscopy...
We present new L-band spectra of 13 outbursting Be stars obtained with ISAAC at the ESO Paranal Observatory. These can be classified in three groups depending on presence or absence emission lines and strength Brα Pfγ relative to those Humphreys from transitions 6–14 end series. are representative circumstellar envelopes different optical depths. For group showing stronger than lines, decrement roughly follows Menzel case-B for optically thin conditions. comparable Brα, Pfγ, emission-line...
B[e] stars are surrounded by cool and dense circumstellar environments where molecules dust formed. These rare display complex spectra whose photospheric features frequently veiled their envelopes, making it difficult to assign them spectral types evolutionary phases. On the basis of a detailed analysis medium-resolution in near-infrared region, together with optical observations available data from astronomical databases, we attempt improve classification infer properties environments. To...
We argue that NSV 11749, an eruption observed in the early twentieth century, was a rare event known as "very late thermal pulse" (VLTP). To support our argument we compare lightcurve of 11749 with those two bonafide VLTP objects to date, V4334 Sgr and V605 Aql, predicted by state art stellar evolution models. Next, explore IPHAS 2MASS catalogues for possible counterparts eruption. Our analysis shows scenario outperforms all other proposed scenarios explanation 11749. identify IPHAS/2MASS...
Abstract Through the modeling of near-infrared photometry star-plus disk systems with codes bedisk / beray , we successfully describe Wide-Field Infrared Survey Explorer ( WISE ) photometric characteristics Be stars in five young open clusters, NGC 663, 869, 884, 3766, and 4755, broadly studied literature. allows previously known to be detected find new candidates which could confirmed spectroscopically. The location color–magnitude diagram, separates them two groups; active (Be hosting a...
Mass-loss rates are one of the most relevant parameters determining evolution massive stars. In particular, at which star loses mass during red-supergiant (RSG) phase is least constrained by observations or theory. this paper, we show how loss RSG affects later star, as well final type supernova towards it leads. We also discuss some possibilities to discriminate between blue stars that went through a and those remained in part Hertzsprung-Russell diagram.
Abstract As the disk formation mechanism(s) in Be stars is(are) as yet unknown, we investigate role of rapidly rotating radiation-driven winds this process. We implemented effects high stellar rotation on m-CAK models accounting for shape star, oblate finite correction factor, and gravity darkening. For a fast obtain two-component wind model, i.e., fast, thin polar latitudes an Ω-slow, dense equatorial regions. use mass densities to explore H α emission profiles following scenarios: (1)...