A5075414421- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Neutrino Physics Research
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Particle physics theoretical and experimental studies
- Radio Astronomy Observations and Technology
- Dark Matter and Cosmic Phenomena
- Spectroscopy and Laser Applications
- Planetary Science and Exploration
- Historical Astronomy and Related Studies
- Computational Physics and Python Applications
- Atmospheric Ozone and Climate
- Geomagnetism and Paleomagnetism Studies
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Space Exploration and Technology
- X-ray Spectroscopy and Fluorescence Analysis
- Intraocular Surgery and Lenses
University of Delaware
2024-2025
Centro de Astrobiología
2015-2025
Consejo Superior de Investigaciones Científicas
2008-2023
Instituto Nacional de Técnica Aeroespacial
2015-2023
Innovalia (Spain)
2023
Universidad Complutense de Madrid
2018-2023
Canadian Bar Association
2021
Universidad de La Laguna
2002-2020
Instituto de Astrofísica de Canarias
2009-2020
National Institute of Astrophysics, Optics and Electronics
2018
The VLT-FLAMES Tarantula Survey (VFTS) is an ESO Large Programme that has obtained multi-epoch optical spectroscopy of over 800 massive stars in the 30 Doradus region Magellanic Cloud (LMC). Here we introduce our scientific motivations and give overview survey targets, including near-infrared photometry comprehensive details data reduction. One principal objectives was to detect binary systems via variations their radial velocities, thus shaping observing strategy. Spectral classifications...
Observing more massive stars The number of that form at each mass is known as the initial function (IMF). For most masses, IMF follows a power-law distribution, first determined by Edwin Salpeter in 1955. Schneider et al. used observations nearby star-forming region 30 Doradus (also Tarantula Nebula) and combined these with stellar modeling to determine its IMF. They found above solar masses than predicted distribution. Because also have biggest influence on their surroundings—for instance,...
Context: The commonly used extinction laws of Cardelli et al. (1989) have limitations that, among other issues, hamper the determination effective temperatures O and early B stars from optical+NIR photometry. Aims: We aim to develop a new family for 30 Doradus, check their general applicability within that region elsewhere, apply them test feasibility using photometry determine temperature OB stars. Methods: use spectroscopy NIR VLT-FLAMES Tarantula Survey optical HST/WFC3 Doradus we analyze...
Context: The star cluster R136 inside the LMC hosts a rich population of massive stars, including most stars known. strong stellar winds these very luminous impact their evolution and surrounding environment. We currently lack detailed knowledge wind structure that is needed to quantify this impact. Aims: To observationally constrain properties in R136, particular parameters related clumping. Methods: simultaneously analyse optical UV spectroscopy 53 O-type 3 WNh-stars using FASTWIND model...
Observations of individual massive stars, super-luminous supernovae, gamma-ray bursts, and gravitational-wave events involving spectacular black-hole mergers, indicate that the low-metallicity Universe is fundamentally different from our own Galaxy. Many transient phenomena will remain enigmatic until we achieve a firm understanding physics evolution stars at low metallicity (Z). The Hubble Space Telescope has devoted 500 orbits to observe 250 Z in ultraviolet (UV) with COS STIS...
Abstract We provide the first reference framework for extremely metal-poor (XMP) OB-type stars. parsed a grid of 0.10 Z⊙fastwind models, covering parameter space O stars and early-B supergiants, through contemporary spectral classification criteria to deliver calibration key stellar properties as function type, tabulated colours most common photometric systems. By using an extensive we account different combinations parameters that result in same morphology range compatible with each subtype...
The IACOB and OWN surveys are two ambitious complementary observational projects which have made available a large multi-epoch spectroscopic database of optical high resolution spectra Galactic massive O-type stars. As first step in the study full sample (more than 350) O stars surveyed by IACOB/OWN projects, we performed quantitative analysis subsample 128 included modern grid standards for spectral classification. We use semi-automatized tools to determine set parameters that can be...
The Tarantula region in the Large Magellanic Cloud contains richest population of spatially resolved massive O-type stars known so far. This unmatched sample offers an opportunity to test models describing their main-sequence evolution and mass-loss properties. Using ground-based optical spectroscopy obtained framework VLT-FLAMES Survey (VFTS), we aim determine stellar, photospheric wind properties 72 presumably single giants, bright giants supergiants confront them with predictions stellar...
We present the IACOB grid-based automatic tool for quantitative spectroscopic analysis of O-stars. The consists an extensive grid FASTWIND models, and a variety programs implemented in IDL to handle observations, perform analysis, visualize results. provides fast objective way determine stellar parameters associated uncertainties large samples O-type stars within reasonable computational time.
The quantitative study of the physical properties and chemical abundances large samples massive blue stars at different metallicities is a powerful tool to understand nature evolution these objects. Their analysis beyond Milky Way challenging, nonetheless it doable best way investigate their behavior in environments. Fulfilling this task an objective requires implementation automatic techniques that can perform analyses systematically, minimizing same time any possible bias. As part...
The contact phase expected to precede the coalescence of two massive stars is poorly characterized due paucity observational constraints. Here we report on discovery VFTS 352, an O-type binary in 30 Doradus region, as most and earliest spectral type overcontact system known date. We derived 3D geometry system, its orbital period $P_{\rm orb}=1.1241452(4)$ d, components' effective temperatures -- $T_1=42\,540\pm280$ K $T_2=41\,120\pm290$ dynamical masses $M_1=28.63\pm0.30 M_{\odot}$ $M_2 =...
We present the first quantitative UV spectroscopic analysis of resolved OB stars in IC1613. Because its alleged very low metallicity (<~1/10 Zo, from HII regions), studies this Local Group dwarf galaxy could become a significant step forward SMC towards extremely metal-poor massive early Universe. HST-COS data covering ~1150-1800{\AA} wavelength range with resolution R~2500. find that targets do exhibit wind features, and these are similar strength to stars. Wind terminal velocities were...
We present a search for neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{136}$Xe using the full KamLAND-Zen 800 dataset with 745 kg enriched xenon, corresponding to an exposure $2.097$ ton yr $^{136}$Xe. This updated benefits from more than twofold increase in exposure, recovery photo-sensor gain, and reduced background muon-induced spallation xenon. Combining previous phase, we obtain lower limit $0\nu\beta\beta$ half-life $T_{1/2}^{0\nu} > 3.8 \times 10^{26}$ at 90% C.L., factor 1.7...
The authors report new radial-velocity measurements of the giant component in recurrent nova T Coronae Borealis. These data have been combined with existing observations to derive a orbital solution and confirm previous estimates for masses. recent optical ultraviolet spectra provide support model which lobe-filling gM3 star loses material main-sequence companion at rate ≡10<SUP>-6</SUP>M_sun;yr<SUP>-1</SUP>. CrB appears be onset runaway case C mass exchange, expect an increase luminosity...
AIMS. We test the hypothesis of O Vz stars (characterized by having HeII4686 stronger in absorption than other He lines their blue-violet spectra) being at a younger evolutionary stage are normal O-type dwarfs. METHODS. have performed quantitative spectroscopic analysis sample 38 and 46 V stars, identified VLT-FLAMES Tarantula Survey 30 Doradus region Large Magellanic Cloud (LMC). obtained stellar wind parameters both samples using FASTWIND atmosphere code IACOB-GBAT grid-based automatic...
The VLT-FLAMES Tarantula Survey has observed hundreds of O-type stars in the 30 Doradus region Large Magellanic Cloud (LMC). We study properties 105 apparently single dwarfs. To determine stellar and wind parameters, we used IACOB-GBAT package, an automatic procedure based on a large grid atmospheric models calculated with FASTWIND code. In addition to classical techniques, applied Bayesian BONNSAI tool estimate evolutionary masses. provide new calibration effective temperature vs. spectral...
We derived photospheric parameters, mass-loss rates, and wind velocities of Galactic O6-O7 stars by analyzing high-resolution spectra in the far-UV UV ranges with line-blanketed, hydrodynamic, non-LTE spherical models. combined from Far Ultraviolet Spectroscopic Explorer (FUSE) range 905-1187 Å International (IUE) archival (1150-3250 Å) used WM-BASIC code Pauldrach et al. to compute model spectra. Lines FUSE include high ionization stages (e.g., O VI) lower abundance non-CNO elements P V)....
Luminous blue variables (LBVs) are expected to play an important role in massive stellar evolution as well being the progenitors of some most luminous supernovae known. In this paper we provide a multiwavelength study population (candidate) LBVs identified within M33. New spectra observational baseline >4yr with respect published data, which is suited identifying LBV outbursts. Multi-epoch optical and mid-IR surveys M33 further constrain variability sample permit search for dusty...