E. J. Alfaro
A5057245587- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- Geophysics and Gravity Measurements
- History and Developments in Astronomy
- Calibration and Measurement Techniques
- Spectroscopy and Laser Applications
- Astrophysics and Cosmic Phenomena
- Historical Studies in Science
- Remote Sensing in Agriculture
- CCD and CMOS Imaging Sensors
- Molecular Spectroscopy and Structure
- Business, Education, Mathematics Research
- Radio Astronomy Observations and Technology
- Health and Medical Education
- Advanced Statistical Methods and Models
- Educational theories and practices
- Historical Astronomy and Related Studies
Instituto de Astrofísica de Andalucía
2016-2025
Royal Observatory
2023
UK Astronomy Technology Centre
2023
Centro Científico Tecnológico Salta - Jujuy
2022
Centro de Estudios de Física del Cosmos de Aragón
2018-2020
Consejo Superior de Investigaciones Científicas
2004-2018
Unidades Centrales Científico-Técnicas
2010-2014
Association Française de Lutte Anti-Rhumastismale
2011
Engineering Arts (United States)
2011
School of Visual Arts
2011
We present the second installment of GOSSS, a massive spectroscopic survey Galactic O stars, based on new homogeneous, high signal-to-noise ratio, R ∼ 2500 digital observations from both hemispheres selected O-Star Catalog (GOSC). In this paper we include bright stars and other objects drawn mostly first version GOSC, all them south δ = −20°, for total number 258 stars. also revise northern sample Paper I to provide full list spectroscopically classified complete B 8, bringing published...
We present the first installment of a massive spectroscopic survey Galactic O stars, based on new, high signal-to-noise ratio, R~2500 digital observations from both hemispheres selected O-Star Catalog Ma\'iz Apell\'aniz et al. (2004) and Sota (2008). The spectral classification system is rediscussed new atlas presented, which supersedes previous versions. Extensive sequences exceptional objects are given, including types Ofc, ON/OC, Onfp, Of?p, Oe, double-lined binaries. remaining normal...
(Abridged) We have used the atmospheric parameters, [alpha/Fe] abundances and radial velocities, determined from Gaia-ESO Survey GIRAFFE spectra of FGK-type stars (iDR1), to provide a chemo-kinematical characterisation disc stellar populations. focuss on subsample 1016 with high quality covering volume |Z|<4.5kpc R in range 2-13kpc. identified thin thick separation vs [M/H] plane, thanks presence low-density region number density distribution. The seem lie progressively thinner layers...
The Gaia-ESO Survey is obtaining high-quality spectroscopic data for about 10^5 stars using FLAMES at the VLT. UVES high-resolution spectra are being collected 5000 FGK-type stars. These analyzed in parallel by several state-of-the-art methodologies. Our aim to present how these analyses were implemented, discuss their results, and describe a final recommended parameter scale defined. We also precision (method-to-method dispersion) accuracy (biases with respect reference values) of...
In the last 15 years different ground-based spectroscopic surveys have been started (and completed) with general aim of delivering stellar parameters and elemental abundances for large samples Galactic stars, complementing Gaia astrometry. Among those surveys, Gaia-ESO Public Spectroscopic Survey (GES), only one performed on a 8m class telescope, was designed to target 100,000 stars using FLAMES ESO VLT (both Giraffe UVES spectrographs), covering all Milky Way populations, special focus open...
WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for William Herschel Telescope, will see first light in late 2022. WEAVE comprises a 2-degree field-of-view prime-focus corrector system, nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and single large IFU. These systems feed dual-beam spectrograph covering wavelength range 366$-$959\,nm at $R\sim5000$, or two shorter ranges $R\sim20\,000$. After summarising...
Context. The Gaia-ESO Public Spectroscopic Survey is an ambitious project designed to obtain astrophysical parameters and elemental abundances for 100 000 stars, including large representative samples of the stellar populations in Galaxy, a well-defined sample 60 (plus 20 archive) open clusters. We provide internally consistent results calibrated on benchmark stars star clusters, extending across very wide range ages. This provides legacy data set intrinsic value, equally wide-ranging...
We study the relationship between age, metallicity, and alpha-enhancement of FGK stars in Galactic disk. The results are based upon analysis high-resolution UVES spectra from Gaia-ESO large stellar survey. explore limitations observed dataset, i.e. accuracy parameters selection effects that caused by photometric target preselection. find colour magnitude cuts survey suppress old metal-rich young metal-poor stars. This suppression may be as high 97% some regions age-metallicity relationship....
Here we describe the first results of Advanced Large Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey, which provides cosmic tomography evolution contents universe over most history. Our novel approach employs 20 contiguous, equal-width, medium-band filters covering from 3500 Å to 9700 Å, plus standard JHKs near-infrared (NIR) bands, observe a total area 4 deg2 on sky. The optical photometric system has been designed maximize number objects with accurate classification by...
(Abridged) We analyzed the stellar parameters and radial velocities of ~1200 stars in five bulge fields as determined from Gaia-ESO survey data (iDR1). use VISTA Variables The Via Lactea (VVV) photometry to obtain reddening values by using a semi-empirical T_eff-color calibration. From Gaussian decomposition metallicity distribution functions, we unveil clear bimodality all fields, with relative size components depending specific position on sky. In agreement some previous studies, find mild...
Context. A key science goal of the Gaia-ESO survey (GES) at VLT is to use kinematics low-mass stars in young clusters and star forming regions probe their dynamical histories how they populate field as become unbound. The clustering around massive Wolf-Rayet binary system γ2 Velorum was one first GES targets.
Aims. Until recently, most high-resolution spectroscopic studies of the Galactic thin and thick discs were mostly confined to objects in solar vicinity. Here we aim at enlarging volume which individual chemical abundances are used characterise discs, using first internal data release Gaia-ESO survey (GES iDR1).
The spatial distribution of elemental abundances in the disc our Galaxy gives insights both on its assembly process and subsequent evolution, stellar nucleogenesis different elements. Gradients can be traced using several types objects as, for instance, (young old) stars, open clusters, HII regions, planetary nebulae. We aim at tracing radial distributions elements produced through nucleosynthetic channels -the alpha-elements O, Mg, Si, Ca Ti, iron-peak Fe, Cr, Ni Sc - by Gaia-ESO idr4...
We use Gaia-ESO Survey iDR4 data to explore the Mg-Al anti-correlation in globular clusters, that were observed as calibrators, a demonstration of quality and analysis. The results compare well with available literature, within 0.1 dex or less, after small (compared internal spreads) offset between UVES GIRAFFE 0.10-0.15 was taken into account. In particular, we present for first time NGC 5927, one most metal-rich clusters studied literature so far [Fe/H]=-0.49 dex, included connect open...
The Advance Large Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey has observed eight different regions of the sky, including sections Cosmic Evolution Survey (COSMOS), DEEP2, European Large-Area Infrared Space Observatory (ELAIS), Great Observatories Origins Deep North (GOODS-N), Sloan Digital Sky (SDSS) and Groth fields using a new photometric system with 20 optical, contiguous ∼300-Å filters plus JHKs bands. filter is designed to optimize effective redshift depth...
On the basis of an extensive new spectroscopic survey Galactic O stars, we introduce Ofc category, which consists normal spectra with C iii λλ4647–4650–4652 emission lines comparable intensity to those Of defining N λλ4634–4640–4642. The former feature is strongly peaked spectral type O5, at all luminosity classes, but preferentially in some associations or clusters and not others. relationships this phenomenon selective λ5696 throughout domain, peculiar, variable Of?p for strong a...
The analysis of the distribution stars in open clusters may yield important information on star formation process and early dynamical evolution stellar clusters. Here we address this issue by systematically characterizing internal spatial structure 16 Milky Way spanning a wide range ages. Cluster have been selected from membership probability based nonparametric method that uses both positions proper motions does not make any priori assumption underlying distributions. is then characterized...
This is the third installment of GOSSS, a massive spectroscopic survey Galactic O stars, based on new homogeneous, high signal-to-noise ratio, R~2500 digital observations selected from O-Star Catalog (GOSC). In this paper we present 142 additional stellar systems with stars both hemispheres, bringing total O-type published within project to 590. Among objects there are 20 stars. We also identify 11 double-lined binaries (SB2s), which 6 O+O type and 5 O+B type, an tripled-lined binary (SB3)...
The Gaia-ESO Survey is a large public spectroscopic survey that aims to derive radial velocities and fundamental parameters of about 10^5 Milky Way stars in the field clusters. Observations are carried out with multi-object optical spectrograph FLAMES, using simultaneously medium resolution (R~20,000) GIRAFFE high (R~47,000) UVES spectrograph. In this paper, we describe methods software used for data reduction, derivation velocities, quality control FLAMES-UVES spectra. Data reduction has...
Context. Chemically inhomogeneous populations are observed in most globular clusters, but not open clusters. Cluster mass seems to play a key role the existence of multiple populations.
Abridged: We used the fourth internal data release of Gaia-ESO survey to characterize bulge chemistry, spatial distribution, kinematics, and compare it chemically with thin thick disks. The sample consist on ~2500 red clump stars in 11 fields ($-10^\circ\leq l\leq+8^\circ$ $-10^\circ\leq b\leq-4^\circ$), a set ~6300 disk selected for comparison. MDF is confirmed be bimodal across whole sampled area, metal-poor dominating at high latitudes. metal-rich exhibit bar-like kinematics display...
Context. The nature of the metallicity gradient inside solar circle (RGC < 8 kpc) is poorly understood, but studies Cepheids and a small sample open clusters suggest that it steepens in inner disk.