A5027344362- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- Historical Studies on Spain
- Spectroscopy and Laser Applications
- Archaeological and Historical Studies
- Atmospheric Ozone and Climate
- Archaeological and Geological Studies
- Atomic and Molecular Physics
- Tribology and Lubrication Engineering
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Geomagnetism and Paleomagnetism Studies
- Laser-induced spectroscopy and plasma
- Pulsars and Gravitational Waves Research
- Molecular Spectroscopy and Structure
- Cosmology and Gravitation Theories
- Historical Studies in Science
- Ionosphere and magnetosphere dynamics
Consejo Nacional de Investigaciones Científicas y Técnicas
2015-2025
Universidad Nacional de La Plata
2015-2025
Instituto de Astrofísica de La Plata
2015-2025
University of Valparaíso
2017-2019
Instituto de Geofísica y Astronomía
2005-2019
Institute of Astronomy and Space Physics
2009
Argentine National Observatory
1987-1989
Context. Among intermediate-mass and massive stars, Be stars are the fastest rotators in main sequence (MS) and, as such, these a cornerstone to validate models of structure evolution rotating stars. Several phenomena, however, induce under- or overestimations either their apparent Vsini, true velocity V.
We present an atlas of Hγ, He i λ 4471 and Mg ii 4481 line profiles obtained in a 10 year observation period 116 Be stars, which enabled many them to be observed at quite different emission epochs. From the best fit with non-LTE, uniform () full limb-darkened model profiles, we determined program stars. To account, some degree, for formation peculiarities related rapid rotation-induced non-uniform distributions temperature gravity on stellar surface, was achieved by considering as free...
Effective temperatures of early-type supergiants are important to test stellar atmosphere- and internal structure-models massive intermediate mass objects at different evolutionary phases. However, these Teff values more or less discrepant depending on the method used determine them. We aim obtain a new calibration parameter for as function observational quantities that highly sensitive ionization balance in photosphere its gas pressure, independent interstellar extinction, much possible...
Massive evolved stars in transition phases, such as luminous blue variables (LBVs), B[e] supergiants (B[e]SGs), and yellow hypergiants (YHGs), are not well understood, yet crucial steps determining accurate stellar galactic evolution models. The circumstellar environments of these reveal their mass-loss history, identifying clues to both individual evolutionary status the connection between objects different phases. Here we present a survey 25 massive (16 B[e]SGs, 6 LBVs, 2 YHGs, 1 Peculiar...
A sample of 97 galactic field Be stars were studied by taking into account the effects induced fast rotation on their fundamental parameters. All program observed in BCD spectrophotometric system order to minimize perturbations produced circumstellar environment spectral photospheric signatures. This is one first attempts at determining stellar masses and ages simultaneously using model atmospheres evolutionary tracks, both calculated for rotating objects. The (τ) normalized respective...
Context. Blue supergiant stars are known to display photometric and spectroscopic variability that is suggested be linked stellar pulsations. Pulsational activity in massive strongly depends on the star’s evolutionary stage assumed connected with mass-loss episodes, appearance of macroturbulent line broadening, formation clumps wind.
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...
The appearance of the B[e] phenomenon in evolved massive stars such as supergiants is still a mystery. While these are generally found to have disks that cool and dense enough for efficient molecule dust condensation, origin disk material unclear. We aim at studying kinematics eccentric binary system GG Car, whose primary component proposed be supergiant. Based on medium- high-resolution near-infrared spectra we analyzed CO-band emission detected from Car. complete structure delivers...
B[e] Supergiants are luminous evolved massive stars. The mass-loss during this phase creates a complex circumstellar environment with atomic, molecular, and dusty regions usually found in rings or disk-like structures. For better comprehension of the mechanisms behind formation these rings, detailed knowledge about their structure dynamics is essential. To address that, we obtained high-resolution optical near-infrared spectra for 8 selected Galactic Supergiants, which CO emission has been...
Context. Variable B supergiants (BSGs) constitute a heterogeneous group of stars with complex photometric and spectroscopic behaviours. They exhibit mass-loss variations experience different types oscillation modes, there is growing evidence that variable stellar winds photospheric pulsations are closely related. Aims. To discuss the wind properties variability evolved B-type stars, we derive new parameters for sample 19 Galactic BSGs by fitting theoretical line profiles H, He, Si to...
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...
Low resolution spectra in the Åwavelength range of 23 stars with B[e] phenomenon are presented. Spectral classification 15 program was performed using BCD spectrophotometric system, based on study Balmer discontinuity, which is independent interstellar and circumstellar dust extinctions gas emissions and/or absorptions. From calibrations parameters we determined ( studied stars. For where this method could not be applied, tried to estimate temperature central star by He i emission lines...
B[e] supergiants (B[e]SGs) are transitional objects in the post-main sequence evolution of massive stars. The small number B[e]SGs known so far Galaxy and Magellanic Clouds indicates that this evolutionary phase is short. Nevertheless, strong aspherical mass loss occurring during phase, which leads to formation rings or disk-like structures, similarity possible progenitors SN1987A emphasize importance for dynamics interstellar medium as well stellar galactic chemical evolution. their...
We present a mini-survey of Galactic B[e] stars mainly undertaken with the Large Binocular Telescope (LBT). show morphological features hydrogen emission lines and an infrared excess, attributed to warm circumstellar dust. In general, these are assumed arise from dense, non-spherical, disc-forming material in which molecules dust can condensate. Due lack reliable luminosities, class contains at very different stellar evolutionary phases like Herbig AeBe, supergiants or planetary nebulae....
The effects of rapid rotation and bi-stability upon the density contrast between equatorial polar directions a B[e] supergiant are re-investigated. Based on new slow solution for different high rotational radiation-driven winds fact that allows change in line-force parameters (α, k, δ), densities about 102–104 times higher than ones. These values qualitative agreement with observations.
Context. The formation and evolution of gas dust environments around B[e] supergiants are still open issues.
Context. Spectroscopic investigations of galactic open clusters are scarce and limited to a reduced sample cluster members.
We aim to improve our knowledge on the structure and dynamics of circumstellar disk LMC B[e] supergiant LHA 120-S 73. High-resolution optical near-IR spectroscopic data were obtained over a period 16 7 years, respectively. The spectra cover diagnostic emission lines from [CaII] [OI], as well CO bands. These features trace at different distances star. analyzed kinematics individual regions by modeling their profiles. A low-resolution mid-infrared spectrum was well, which provides information...
Context. Stellar physical properties of star clusters are poorly known. Aims. Our goals to perform a spectrophotometric study the B population in open derive accurate stellar parameters, search for presence circumstellar envelopes, and discuss characteristics these stars. Methods. The BCD system is powerful tool obtain fundamental parameters infer main clusters: distance modulus, color excess, age. We inspected Balmer discontinuity seek disks identify Be-star candidates. High resolution...
Context.He-weak and He-strong stars are chemically peculiar AB objects whose He lines anomalously weak or strong for their MK spectral type. The determination of fundamental parameters these is often more complex than normal due to abundance anomalies.
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...