Grants related:
General
This project aims at the searching, observation and analysis of massive stars in nearby galaxies to provide a solid empirical ground to understand their physical properties as a function of those key parameters that gobern their evolution (i.e. mass, spin, metallicity, mass loss, and binary interaction).
Massive stars are central objects to Astrophysics. Born with at least 8 solar masses, their evolution proceeds very fast, yielding large amounts of nuclear processed material by means of strong stellar winds (loosing up to 90% of their initial mass before facing a violent death as Supernova) and emitting intense radiation fields. Despite their scarcity, massive stars play a decisive role in many aspects of the evolution of the Cosmos (e.g. they are primary agents of the chemical and dynamical evolution of galaxies and have been proposed as key agents in the reionization of the Universe). Along their complex evolution, they are associated with the most extreme stellar objects (O-type and WR stars; blue and red supergiants; luminous blue variables; massive stellar black holes, neutron stars and magnetars; massive X- and gamma-ray binaries). They are also the origin of newly studied phenomena such as long-duration GRBs or the recently detected gravitational waves produced by a merger of two massive black holes or neutron stars. From a practical perspective, massive stars have become invaluable indicators of present-day abundances and distances in external galaxies, even beyond the Local Group. In addition, the interpretation of the light emitted by H II regions and starburst galaxies relies on our knowledge of the effect that the strong ionizing radiation emitted by these hot stellar objects produces on the surrounding interstellar medium.
This project aims at the searching, observation and analysis of massive stars in nearby galaxies to provide a solid empirical ground to understand their physical properties as a function of those key parameters that gobern their evolution (i.e. mass, spin, metallicity, mass loss, and binary interaction). In this endeavour, the project benefits from best quality observations obtained with the last generation of facilities available at the Canary and the ESO observatories, as well as other observations of interest provided from space missions such as Gaia, HST, IUE and TESS. Samples with a few to several hundreds of individual massive stars in different evolutionary stages and metallicity environments are then analyzed with the last generation of stellar atmosphere codes and optimized tools for the quantitative spectroscopic analysis of massive stars to extract as much empirical information as possible about stellar+wind parameters, surface abundances and spectroscopic variability.
The main research lines presently active in the project are:
- the observation and analysis of large samples of massive OB stars in the Milky Way;
- the exploration of the hidden population of massive stars in the Milky Way;
- the searching, observation and analysis of massive extragalactic stars, with special emphasis in those found in low metallicity galaxies;
- the development and use of model atmospheres, model atoms and numerical tools for the analysis of massive stars.
Members
Results
Highlights 2020
1. The IACOB project presents empirical evidence of the scarcity of Galactic O-type stars with masses 40-80 Msol close to the theoretical zero age main sequence. Th reason of this result could be indicating that the accretion rate of mass during the stars formation process of massive stars could be lower than traditionally considered.
2. Presented empirical evidence of the existence of multiple star forming bursts in the Cygnus OB2 massive star formation region. The way is paved for the first in-depth study of the massive star population of the Cygus-X region in the Milky Way benefiting from the WEAVE survey.
3. Studied membership and kinematical properties in a sample of 80 blue and red supergiants in the PerOB1 association by using high resolution multi-epoch spectroscopy and Gaia astrometry data. A forthcoming spectroscopic study of this sample of star will provide new empirical clues to improve our understanding of massive stars evolution.
4. The MAMSIE-IACOB collaboration presents first in-depth study of the pulsational propeties of a large sample of massive Galactic OB-type stars by means of the combined study of high-resolution spectroscopic data from HERMES, FIES and SONG and high cadence photometric data provide by the TESS mission.
5. Estimated that the binarity fraction for evolved high-mass stars (red supergiants) should be at least 0.15±0.03.
6. Identified the first strong candidate to be a super-AGB star in the Galaxy (VX Sgr).
Scientific activity
Related publications
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The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data productsContext. 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 the Galaxy, and a well-defined sample of 60 (plus 20 archive) open clusters. We provide internally consistent resultsGilmore, G. et al.
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102022 -
The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy,★Context. In the last 15 years different ground-based spectroscopic surveys have been started (and completed) with the general aim of delivering stellar parameters and elemental abundances for large samples of Galactic stars, complementing Gaia astrometry. Among those surveys, the Gaia-ESO Public Spectroscopic Survey, the only one performed on a 8mRandich, S. et al.
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102022 -
An X-ray-quiet black hole born with a negligible kick in a massive binary within the Large Magellanic CloudStellar-mass black holes are the final remnants of stars born with more than 15 solar masses. Billions are expected to reside in the Local Group, yet only a few are known, mostly detected through X-rays emitted as they accrete material from a companion star. Here, we report on VFTS 243: a massive X-ray-faint binary in the Large Magellanic CloudShenar, Tomer et al.
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72022 -
The Tarantula Massive Binary Monitoring. VI. Characterisation of hidden companions in 51 single-lined O-type binaries: A flat mass-ratio distribution and black-hole binary candidatesContext. Massive binaries hosting a black hole (OB+BH) represent a critical phase in the production of BH mergers in the context of binary evolution. In spite of this, such systems have so far largely avoided detection. Single-lined spectroscopic (SB1) O-type binaries are ideal objects to search for elusive BH companions. Moreover, SB1 binariesShenar, T. et al.
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92022 -
Constraining the overcontact phase in massive binary evolution. II. Period stability of known O+O overcontact systemsContext. Given that mergers are often invoked to explain many exotic phenomena in massive star evolution, understanding the evolutionary phase directly preceding a merger, the overcontact phase, is of crucial importance. Despite this, large uncertainties exist in our understanding of the evolution of massive overcontact binaries. Aims: We aim toAbdul-Masih, Michael et al.
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102022 -
The IACOB project. VII. The rotational properties of Galactic massive O-type stars revisitedContext. Stellar rotation is of key importance in the formation process, the evolution, and the final fate of massive stars. Aims: We perform a reassessment of the empirical rotational properties of Galactic massive O-type stars using the results from a detailed analysis of ground-based multi-epoch optical spectra obtained in the framework of theHolgado, G. et al.
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92022 -
A new reference catalogue for the very metal-poor Universe: +150 OB stars in Sextans ALocal Group (LG) very metal-poor massive stars are the best proxy for the First Stars of the Universe and fundamental to modelling the evolution of early galaxies. These stars may follow new evolutionary pathways restricted to very low metallicities, such as chemically homogeneous evolution (CHE). However, given the great distance leap needed toLorenzo, M. et al.
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112022 -
The VLT-FLAMES survey of massive stars. NGC 2004#115: A triple system hosting a possible short period B+BH binaryContext. NGC 2004#115 was classified as a single lined Be spectroscopic binary in the Large Magellanic Cloud. Its Hα morphology is reminiscent of the Galactic systems LB-1 and HR 6819, both of which are proposed as either Be+BH or Be+stripped He-star systems. Aims: Multi-epoch optical spectra of NGC 2004#115 are used to determine if this binary canLennon, D. J. et al.
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92022 -
The Gaia-ESO survey: A spectroscopic study of the young open cluster NGC 3293We present a spectroscopic analysis of the GIRAFFE and UVES data collected by the Gaia-ESO survey for the young open cluster NGC 3293. Archive spectra from the same instruments obtained in the framework of the `VLT-FLAMES survey of massive stars' are also analysed. Atmospheric parameters, non-local thermodynamic equilibrium (LTE) chemicalMorel, T. et al.
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92022 -
The Internal Proper Motion Kinematics of NGC 346: Past Formation and Future EvolutionWe investigate the internal kinematics of the young star-forming region NGC 346 in the Small Magellanic Cloud (SMC). We used two epochs of deep F555W and F814W Hubble Space Telescope Advanced Camera for Surveys observations with an 11 yr baseline to determine proper motions and study the kinematics of different populations, as identified by theirSabbi, E. et al.
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92022 -
Westerlund 1 under the light of Gaia EDR3: Distance, isolation, extent, and a hidden populationContext. The young massive cluster Westerlund 1 offers the promise of a grand laboratory for the study of high-mass star evolution, but its basic parameters are still poorly known. Aims: In this paper, we aim at a better characterisation of the cluster by determining some basic kinematic properties and analysing the area surrounding the cluster andNegueruela, I. et al.
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82022 -
The EURONEAR Lightcurve Survey of Near Earth Asteroids 2017-2020This is the fourth data paper publishing lightcurve survey work of 52 Near Earth Asteroids (NEAs) using 10 telescopes available to the EURONEAR network between 2017 and 2020. Forty six targets were not observed before our runs (88% of the sample) but some of these were targeted during the same oppositions mainly by Brian Warner. We propose newVaduvescu, O. et al.
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102022 -
Red supergiant stars in binary systems. I. Identification and characterization in the small magellanic cloud from the UVIT ultraviolet imaging surveyWe aim to identify and characterize binary systems containing red supergiant (RSG) stars in the Small Magellanic Cloud (SMC) using a newly available ultraviolet (UV) point source catalogue obtained using the Ultraviolet Imaging Telescope (UVIT) on board AstroSat. We select a sample of 560 SMC RSGs based on photometric and spectroscopic observationsPatrick, L. R. et al.
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72022 -
The Gaia-ESO Survey: The analysis of the hot-star spectraContext. The Gaia-ESO Survey (GES) is a large public spectroscopic survey that has collected, over a period of six years, spectra of ~10 5 stars. This survey provides not only the reduced spectra, but also the stellar parameters and abundances resulting from the analysis of the spectra. Aims: The GES dataflow is organised in 19 working groupsBlomme, R. et al.
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52022 -
Stellar mergers as the origin of the blue main-sequence band in young star clustersRecent high-quality Hubble Space Telescope photometry shows that the main-sequence stars of young star clusters form two discrete components in the colour-magnitude diagram. On the basis of their distribution in the colour-magnitude diagram, we show that stars of the blue main-sequence component can be understood as slow rotators originating fromWang, Chen et al.
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22022 -
Properties of the Be-type stars in 30 DoradusThe evolutionary status of Be-type stars remains unclear, with both single-star and binary pathways having been proposed. Here, VFTS spectroscopy of 73 Be-type stars, in the spectral-type range, B0-B3, is analysed to estimate projected rotational velocities, radial velocities, and stellar parameters. They are found to be rotating faster than theDufton, P. L. et al.
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52022 -
Near-IR narrow-band imaging with CIRCE at the Gran Telescopio Canarias: Searching for Lyα-emitters at z ∼ 9.3Context. Identifying very high-redshift galaxies is crucial for understanding the formation and evolution of galaxies. However, many questions still remain, and the uncertainty on the epoch of reionization is large. In this approach, some models allow a double-reionization scenario, although the number of confirmed detections at very high z isCabello, C. et al.
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32022 -
The nature of the Cygnus extreme B supergiant 2MASS J20395358+42225052MASS J20395358+4222505 is an obscured early B supergiant near the massive OB star association Cygnus OB2. Despite its bright infrared magnitude (K s = 5.82) it has remained largely ignored because of its dim optical magnitude (B = 16.63, V = 13.68). In a previous paper, we classified it as a highly reddened, potentially extremely luminous, early BHerrero, A. et al.
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42022 -
Massive stars in extremely metal-poor galaxies: a window into the pastCosmic history has witnessed the lives and deaths of multiple generations of massive stars, all of them invigorating their host galaxies with ionizing photons, kinetic energy, fresh material, and stellar-mass black holes. Ubiquitous engines as they are, astrophysics needs a good understanding of their formation, evolution, properties and yieldsGarcia, Miriam et al.
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62021 -
MONOS: Multiplicity Of Northern O-type Spectroscopic systems. II. Orbit review and analysis for 35 single-lined spectroscopic binary systems and candidatesContext. Massive stars are a key element for understanding the chemical and dynamical evolution of galaxies. Stellar evolution is conditioned by many factors: Rotation, mass loss, and interaction with other objects are the most important ones for massive stars. During the first evolutionary stages of stars with initial masses (i.e., M ZAMS) in theTrigueros Páez, E. et al.
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112021
