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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Blue supergiants as a progenitor of intermediate-luminosity red transientsThe current perspective about the explosions of massive hydrogen-rich blue supergiants is that they resemble SN 1987A. These so-called peculiar Type II supernovae, however, are one of the rarest types of supernovae and may not hence be the fate of all blue supergiants. In this work, we explore other explosion scenarios for blue supergiants. WeMoriya, Takashi J. et al.
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122024 -
WEAVE First Light Observations: Origin and Dynamics of the Shock Front in Stephan's QuintetWe present a detailed study of the large-scale shock front in Stephan's Quintet, a by-product of past and ongoing interactions. Using integral-field spectroscopy from the new William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE), recent 144 MHz observations from the LOFAR Two-metre Sky Survey, and archival data from the Very LargeArnaudova, M. I. et al.
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Constraining the overcontact phase in massive binary evolution: III. Period stability of known B+B and O+B overcontact systemsContext. Binary systems play a crucial role in massive star evolution. Systems composed of B-type and O-type stars are of particular interest due to their potential to lead to very energetic phenomena or the merging of exotic compact objects. Aims. We aim to determine the orbital period variations of a sample of B+B and O+B massive overcontactVrancken, Jasmine et al.
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Exploring massive star early evolution: the case of the Herschel 36 A triple systemTheoretical models show that some massive stars have not yet arrived at the zero-age main sequence (ZAMS) at the end of the accretion phase. At that time, they have lost their thick envelopes and thus could be optically visible. Although some candidates to optically observable ZAMS stars have been reported, the evolutionary status of none of themArias, Julia I. et al.
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112024 -
Boron depletion in Galactic early B-type stars reveals two different main sequence star populationsContext. The evolution and fate of massive stars are thought to be affected by rotationally induced internal mixing. The surface boron abundance is a sensitive tracer of this in early B-type main sequence stars. Aims. We test current stellar evolution models of massive main sequence stars which include rotational mixing through a systematic studyProffitt, Charles R. et al.
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102024 -
Binarity at LOw Metallicity (BLOeM): A spectroscopic VLT monitoring survey of massive stars in the SMCSurveys in the Milky Way and Large Magellanic Cloud have revealed that the majority of massive stars will interact with companions during their lives. However, knowledge of the binary properties of massive stars at low metallicity, and therefore in conditions approaching those of the Early Universe, remain sparse. We present the Binarity at LOwWang, C. et al.
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102024 -
The IACOB project: XII. New grid of northern standards for the spectral classification of B-type starsContext. With the advent of large spectroscopic surveys, automated stellar parameter determination has become commonplace. Nevertheless, spectral classification still offers a quick and useful alternative for obtaining parameter estimates for large samples of spectra of varying quality. Aims. We present a new atlas of stellar spectra covering the BNegueruela, I. et al.
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102024 -
Empirical mass-loss rates and clumping properties of O-type stars in the Large Magellanic CloudContext. The nature of mass-loss in massive stars is one of the most important and difficult to constrain processes in the evolution of massive stars. The largest observational uncertainties are related to the influence of metallicity and wind structure with optically thick clumps. Aims. We aim to constrain the wind parameters of sample of 18 OHawcroft, C. et al.
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X-Shooting ULLYSES: Massive stars at low metallicity: V. Effect of metallicity on surface abundances of O starsContext. Massive stars rotate faster, on average, than lower mass stars. Stellar rotation triggers hydrodynamical instabilities which transport angular momentum and chemical species from the core to the surface. Models of high-mass stars that include these processes predict that chemical mixing is stronger at lower metallicity. Aims. We aim to testMartins, F. et al.
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X-Shooting ULLYSES: Massive stars at low metallicity: IV. Spectral analysis methods and exemplary results for O starsContext. The spectral analysis of hot, massive stars is a fundamental astrophysical method of determining their intrinsic properties and feedback. With their inherent, radiation-driven winds, the quantitative spectroscopy for hot, massive stars requires detailed numerical modeling of the atmosphere and an iterative treatment in order to obtain theSander, A. A. C. et al.
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92024 -
X-Shooting ULLYSES: Massive stars at low metallicity. III. Terminal wind speeds of ULLYSES massive starsContext. The winds of massive stars have a significant impact on stellar evolution and on the surrounding medium. The maximum speed reached by these outflows, the terminal wind speed v ∞, is a global wind parameter and an essential input for models of stellar atmospheres and feedback. With the arrival of the ULLYSES programme, a legacy UVHawcroft, C. et al.
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82024 -
X-Shooting ULLYSES: Massive stars at low metallicity. II. DR1: Advanced optical data products for the Magellanic CloudsContext. The XShootU project aims to obtain ground-based optical to near-infrared spectroscopy of all targets observed by the Hubble Space Telescope (HST) under the Director's Discretionary program ULLYSES. Using the medium-resolution spectrograph X-shooter, spectra of 235 OB and Wolf-Rayet (WR) stars in subsolar metallicity environments have beenSana, H. et al.
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82024 -
Rotational synchronisation of B-type binaries in 30 DoradusThe spin evolution of stars in close binary systems can be strongly affected by tides. We investigate the rotational synchronisation of the stellar components for 69 SB1 systems and 14 SB2 B-type systems in the 30 Doradus region of the Large Magellanic Cloud using observations from the VFTS and BBC surveys. Their orbital periods range from a few toLennon, D. J. et al.
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82024 -
The IACOB project. X. Large-scale quantitative spectroscopic analysis of Galactic luminous blue starsContext. Blue supergiants (BSGs) are key objects for understanding the evolution of massive stars, which play a crucial role in the evolution of galaxies. However, discrepancies between theoretical predictions and empirical observations have opened up important questions yet to be answered. Studying statistically significant and unbiased samples ofde Burgos, A. et al.
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72024 -
The IACOB project. XI. No increase in mass-loss rates over the bistability regionThe properties of blue supergiants are key for constraining the end of the main sequence (MS) of massive stars. Whether the observed drop in the relative number of fast-rotating stars below ≈21 kK is due to enhanced mass-loss rates at the location of the bistability jump, or the result of the end of the MS is still debated. Here, we combine newlyde Burgos, A. et al.
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72024 -
Expanded Sample of Small Magellanic Cloud Ultraviolet Dust Extinction Curves: Correlations between the 2175 Å Bump, q <SUB>PAH</SUB>, Ultraviolet Extinction Shape, and N(H I)/A(V)The Small Magellanic Cloud (SMC) shows a large variation in ultraviolet (UV) dust extinction curves, ranging from Milky Way (MW) like to significantly steeper curves with no detectable 2175 Å bump. This result is based on a sample of only nine sight lines. From Hubble Space Telescope Space Telescope Imaging Spectrograph and IUE spectra of OB starsGordon, Karl D. et al.
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72024 -
The colliding-wind binary HD 168112Context. Radio surveys of early-type stars have revealed a number of non-thermal emitters. Most of these have been shown to be binaries, where the collision between the two stellar winds is responsible for the non-thermal emission. Aims: HD 168112 is a non-thermal radio emitter, whose binary nature has only recently been confirmed spectroscopicallyBlomme, R. et al.
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72024 -
Evidence for very massive stars in extremely UV-bright star-forming galaxies at z ∼ 2.2-3.6We present a comprehensive analysis of the presence of very massive stars (VMS > 100 M ⊙) in the integrated spectra of 13 UV-bright star-forming galaxies at 2.2 ≲ z ≲ 3.6 taken with the Gran Telescopio Canarias (GTC). These galaxies have very high UV absolute magnitudes (M UV ≃ −24), intense star formation (star formation rate ≃100 − 1000 M ⊙ yr −1Upadhyaya, A. et al.
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62024 -
Boron Abundances in Early B Dwarfs of the Galactic Open Cluster NGC 3293New boron abundances or upper limits have been determined for eight early B stars in the young Galactic open cluster NGC 3293, using UV spectra obtained by the Hubble Space Telescope Cosmic Origins Spectrograph. With previous observations, there are now 18 early B stars in this cluster with boron measurements. Six of the newly observed stars haveProffitt, Charles R. et al.
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62024 -
Detection of extragalactic magnetic massive starsContext. Studies of the magnetic characteristics of massive stars have recently received significant attention because they are progenitors of highly magnetised compact objects. Stars initially more massive than about 8 M ⊙ leave behind neutron stars and black holes by the end of their evolution. The merging of binary compact remnant systemsHubrig, S. et al.
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62024