Subvenciones relacionadas:
General
Las estrellas masivas son objetos claves para la Astrofísica. Estas estrellas nacen con más de 8 masas solares, lo que las condena a morir como Supernovas. Durante su rápida evolución liberan, a través de fuertes vientos estelares, gran cantidad de material procesado en su núcleo y, en determinadas fases evolutivas, emiten gran cantidad de radiación ionizante. Como consecuencia, las estrellas masivas juegan un papel fundamental en muchos aspectos de la evolución del Cosmos; p. ej., son uno de los motores principales de la evolución química y dinámica de las galaxias y han sido propuestas como agentes clave en la reionización del Universo. A lo largo de su evolución, se asocian con los objetos estelares mas extremos (estrellas O y WR; supergigantes azules y rojas; variables luminosas azules; agujeros negros, estrellas de neutrones y magnetars; estrellas binarias masivas de rayos X y gamma). También son el origen de los GRBs de larga duración y están asociadas con las recientes detecciones de ondas gravitacionales. Desde un punto de vista practico, las estrellas masivas son valiosos indicadores de abundancias y distancias en galaxias externas, incluso mas allá del Grupo Local. Ademas, la interpretación de la luz emitida por regiones HII y galaxias starburst se basa en nuestro conocimiento del efecto que produce la radiación ionizante emitida por las estrellas masivas en el medio interestelar.
Este proyecto esta enfocado a la búsqueda, observación y análisis de estrellas masivas en galaxias cercanas con la finalidad de proporcionar un marco empírico solido que nos permita entender sus propiedades físicas en función de parámetros clave que gobiernan su evolución (tales como masa, rotacion, metalicidad, perdida de masa e interacción binaria). Para ello, el proyecto se basa en observaciones de gran calidad obtenidas con telescopios de los observatorios de Canarias y de la ESO, complementadas con otras observaciones de interés proporcionadas por misiones espaciales como Gaia, HST, IUE y TESS. Como una parte clave de este proyecto, observaciones espectroscópicas de estrellas masivas en distintos estados evolutivos y localizadas en entornos de diferente metalicidad son analizadas haciendo uso de la ultima generación de códigos de atmósfera estelar y herramientas de análisis espectroscópico cuantitativo optimizadas para estrellas masivas con la finalidad de extraer la mayor cantidad de información empírica posible sobre parámetros estelares y abundancias.
Las principales lineas activas en el proyecto son:
- la observación y análisis de grandes muestras de estrellas OB en la Vía Láctea;
- la exploración de la población estelar masiva localizada en regiones oscurecidas de la Vía Láctea;
- la búsqueda, observación y análisis de estrellas masivas extragalácticas, poniendo un especial énfasis en galaxias de baja metalicidad;
- el desarrollo y uso de modelos de atmósfera, modelos atómicos y herramientas numéricas para el análisis de estrellas masivas.
Miembros
Resultados
- Como parte de su tesis, S.R. Berlanas ha publicado una serie de tres articulos en los que se estudian en detalle varios aspectos relacionados con la poblacion estelar masiva de la asociacion Cygnus OB2 utilizando espectroscopia obtenida con INT y datos de paralajes proporcinoados por Gaia DR2.
- G. Holgado ha finalizado su tesis doctoral en la que presenta un estudio espectroscopico detallado de la muestra de estrellas O Galacticas más grande considerada hasta el momento.
- Hemos investigado en detalle la variabilidad espectroscopica y fotometrica de dos supergigantes azules (rho Leo y kappa Cas) a partir de espectroscopia multiepoca HERMES/FIES/SONG y datos fotometricos proporcionados por las misiones Hipparcos y K2. Nuestros analisis apuntan hacia la confirmacion de la existencia de "internal gravity waves" en este tipo de estrellas.
- Hemos encontrado dos nuevas acumulaciones de estrellas masivas en la Via Lactea con un alineamiento casual (MASGOMAS-6A+B). Localizadas a una longitud Galactica de 38 grados, la primera acumulacion (a 3.9 kpc) continene 2 estrellas WR y varias enanas O, mientras que la segunda (a 9.6 kpc) contine una LBV y una poblacion evolucionada de supergigantes azules.
- Hemos contribuido a presentar un censo actualizado de la población estelar masiva del cúmulo del Quintuplete, uno de los cúmulos jovenes más masivos en la Galaxia.
Actividad científica
Publicaciones relacionadas
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Young LMC clusters: the role of red supergiants and multiple stellar populations in their integrated light and CMDsThe optical integrated spectra of three Large Magellanic Cloud young stellar clusters (NGC 1984, NGC 1994 and NGC 2011) exhibit concave continua and prominent molecular bands which deviate significantly from the predictions of single stellar population (SSP) models. In order to understand the appearance of these spectra, we create a set of youngAsa'd, Randa S. et al.
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112017 -
Gran Telescopio Canarias observations of an overdense region of Lyman α emitters at z = 6.5We present the results of our search near the end of the Reionization Epoch for faint galaxies. This has been done using very deep OSIRIS images obtained at the Gran Telescopio Canarias (GTC). Our observations focus around two close, massive Lyman α emitters (LAEs) at redshift 6.5, discovered in the SXDS field within a large-scale overdense regionChanchaiworawit, K. et al.
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82017 -
The VLT-FLAMES Tarantula Survey. XXVI. Properties of the O-dwarf population in 30 DoradusContext. The VLT-FLAMES Tarantula Survey has observed hundreds of O-type stars in the 30 Doradus region of the Large Magellanic Cloud (LMC). Aims: We study the properties of a statistically significant sample of O-type dwarfs in the same star-forming region and test the latest atmospheric and evolutionary models of the early main-sequence phase ofSabín-Sanjulián, C. et al.
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52017 -
Legacy ExtraGalactic UV Survey with The Hubble Space Telescope: Stellar Cluster Catalogs and First Insights Into Cluster Formation and Evolution in NGC 628We report the large effort that is producing comprehensive high-level young star cluster (YSC) catalogs for a significant fraction of galaxies observed with the Legacy ExtraGalactic UV Survey (LEGUS) Hubble treasury program. We present the methodology developed to extract cluster positions, verify their genuine nature, produce multiband photometryAdamo, A. et al.
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62017 -
Physical properties of the first spectroscopically confirmed red supergiant stars in the Sculptor Group galaxy NGC 55We present K-band Multi-Object Spectrograph (KMOS) observations of 18 red supergiant (RSG) stars in the Sculptor Group galaxy NGC 55. Radial velocities are calculated and are shown to be in good agreement with previous estimates, confirming the supergiant nature of the targets and providing the first spectroscopically confirmed RSGs in NGC 55Patrick, L. et al.
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62017 -
The VLT-FLAMES Tarantula Survey . XXIV. Stellar properties of the O-type giants and supergiants in 30 DoradusContext. The Tarantula region in the Large Magellanic Cloud (LMC) contains the 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. Aims: Using ground-based optical spectroscopy obtained in theRamírez-Agudelo, O. H. et al.
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42017 -
The VLT-FLAMES Tarantula Survey. XXV. Surface nitrogen abundances of O-type giants and supergiantsContext. Theoretically, rotation-induced chemical mixing in massive stars has far reaching evolutionary consequences, affecting the sequence of morphological phases, lifetimes, nucleosynthesis, and supernova characteristics. Aims: Using a sample of 72 presumably single O-type giants to supergiants observed in the context of the VLT-FLAMES TarantulaGrin, N. J. et al.
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42017 -
Constraining the Epoch of Reionization from the Observed Properties of the High-z UniverseWe combine observational data on a dozen independent cosmic properties at high-z with the information on reionization drawn from the spectra of distant luminous sources and the cosmic microwave background (CMB) to constrain the interconnected evolution of galaxies and the intergalactic medium since the dark ages. The only acceptable solutions areSalvador-Solé, E. et al.
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12017 -
The VLT-FLAMES Tarantula Survey. XXIII. Two massive double-lined binaries in 30 DoradusAims: We investigate the characteristics of two newly discovered short-period, double-lined, massive binary systems in the Large Magellanic Cloud, VFTS 450 (O9.7 II-Ib + O7::) and VFTS 652 (B1 Ib + O9: III:). Methods: We perform model-atmosphere analyses to characterise the photospheric properties of both members of each binary (denoting theHowarth, I. D. et al.
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102015 -
Discovery of the Massive Overcontact Binary VFTS352: Evidence for Enhanced Internal MixingThe contact phase expected to precede the coalescence of two massive stars is poorly characterized due to the paucity of observational constraints. Here we report on the discovery of VFTS 352, an O-type binary in the 30 Doradus region, as the most massive and earliest spectral type overcontact system known to date. We derived the 3D geometry of theAlmeida, L. A. et al.
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102015 -
The Brightest Young Star Clusters in NGC 5253.The nearby dwarf starburst galaxy NGC 5253 hosts a number of young, massive star clusters, the two youngest of which are centrally concentrated and surrounded by thermal radio emission (the “radio nebula”). To investigate the role of these clusters in the starburst energetics, we combine new and archival Hubble Space Telescope images of NGC 5253Calzetti, D. et al.
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102015 -
The VLT-FLAMES Tarantula Survey. XXII. Multiplicity properties of the B-type starsWe investigate the multiplicity properties of 408 B-type stars observed in the 30 Doradus region of the Large Magellanic Cloud with multi-epoch spectroscopy from the VLT-FLAMES Tarantula Survey (VFTS). We use a cross-correlation method to estimate relative radial velocities from the helium and metal absorption lines for each of our targets. ObjectsDunstall, P. R. et al.
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82015 -
LEGUS Discovery of a Light Echo Around Supernova 2012awWe have discovered a luminous light echo around the normal Type II-Plateau Supernova (SN) 2012aw in Messier 95 (M95; NGC 3351), detected in images obtained approximately two years after explosion with the Wide Field Channel 3 on board the Hubble Space Telescope by the Legacy ExtraGalactic Ultraviolet Survey. The multi-band observations span fromVan Dyk, S. D. et al.
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62015 -
The VLT-FLAMES Tarantula Survey. XIX. B-type supergiants: Atmospheric parameters and nitrogen abundances to investigate the role of binarity and the width of the main sequenceContext. Model atmosphere analyses have been previously undertaken for both Galactic and extragalactic B-type supergiants. By contrast, little attention has been given to a comparison of the properties of single supergiants and those that are members of multiple systems. Aims: Atmospheric parameters and nitrogen abundances have been estimated forMcEvoy, C. M. et al.
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32015 -
The VLT-FLAMES Tarantula Survey. XVIII. Classifications and radial velocities of the B-type starsWe present spectral classifications for 438 B-type stars observed as part of the VLT-FLAMES Tarantula Survey (VFTS) in the 30 Doradus region of the Large Magellanic Cloud. Radial velocities are provided for 307 apparently single stars, and for 99 targets with radial-velocity variations which are consistent with them being spectroscopic binaries. WeEvans, C. J. et al.
Fecha de publicación:
22015 -
Legacy Extragalactic UV Survey (LEGUS) With the Hubble Space Telescope. I. Survey DescriptionThe Legacy ExtraGalactic UV Survey (LEGUS) is a Cycle 21 Treasury program on the Hubble Space Telescope aimed at the investigation of star formation and its relation with galactic environment in nearby galaxies, from the scales of individual stars to those of ˜kiloparsec-size clustered structures. Five-band imaging from the near-ultraviolet to theCalzetti, D. et al.
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22015 -
Building galaxies, stars, planets and the ingredients for life between the stars. The science behind the European Ultraviolet-Visible ObservatoryThis contribution gathers the contents of the white paper submitted by the UV community to the Call issued by the European Space Agency in March 2013, for the definition of the L2 and L3 missions in the ESA science program. We outlined the key science that a large UV facility would make possible and the instrumentation to be implemented. The growthGómez de Castro, A. I. et al.
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112014 -
The VLT-FLAMES Tarantula Survey. XVII. Physical and wind properties of massive stars at the top of the main sequenceThe evolution and fate of very massive stars (VMS) is tightly connected to their mass-loss properties. Their initial and final masses differ significantly as a result of mass loss. VMS have strong stellar winds and extremely high ionising fluxes, which are thought to be critical sources of both mechanical and radiative feedback in giant H iiBestenlehner, J. M. et al.
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Winds of Low-metallicity OB-type Stars: HST-COS Spectroscopy in IC 1613We present the first quantitative ultraviolet spectroscopic analysis of resolved OB stars in IC 1613. Because of its alleged very low metallicity (lsim1/10 Z ☉, from H II regions), studies in this Local Group dwarf galaxy could become a significant step forward from the Small Magellanic Cloud (SMC) toward the extremely metal-poor massive stars ofGarcia, M. et al.
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62014 -
The VLT-FLAMES Tarantula Survey. XIII: On the nature of O Vz stars in 30 DoradusContext. O Vz stars, a subclass of O-type dwarfs characterized by having He ii λ4686 stronger in absorption than any other helium line in their blue-violet spectra, have been suggested to be on or near the zero-age main sequence (ZAMS). If their youth were confirmed, they would be key objects with which to advance our knowledge of the physicalSabín-Sanjulián, C. et al.
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42014