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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A massive open cluster hiding in full sightObscuration and confusion conspire to limit our knowledge of the inner Milky Way. Even at moderate distances, the identification of stellar systems becomes compounded by the extremely high density of background sources. Here, we provide a very revealing example of these complications by unveiling a large, massive, young cluster in the SagittariusNegueruela, I. et al.
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82021 -
Hubble spectroscopy of LB-1: Comparison with B+black-hole and Be+stripped-star modelsContext. LB-1 (alias ALS 8775) has been proposed as either an X-ray dim B-type star plus black hole (B+BH) binary or a Be star plus an inflated stripped star (Be+Bstr) binary. The latter hypothesis contingent upon the detection and characterization of the hidden broad-lined star in a composite optical spectrum. Aims: Our study is aimed at testingLennon, D. J. et al.
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52021 -
Convective core sizes in rotating massive stars. I. Constraints from solar metallicity OB field starsContext. Spectroscopic studies of Galactic O and B stars show that many stars with masses above 8 M ⊙ have been observed in the Hertzsprung-Russell (HR) diagram just beyond the main-sequence (MS) band, as predicted by stellar models computed with a moderate overshooting. This may be an indication that the convective core sizes in stars in the upperMartinet, S. et al.
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42021 -
Assessing the Stellar Population and the Environment of an H II Region on the Far Side of the GalaxyWe have investigated the stellar and interstellar content of the distant star formation region IRAS 17591-2228 (WISE H II region GAL 007.47+0.06). It is associated with a water maser, whose parallax distance is $d={20.4}_{-2.2}^{+2.8}$ kpc, supported by independent measurements of proper motion and radial velocity. It is projected in the sameChené, André-Nicolas et al.
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42021 -
Mapping the core of the Tarantula Nebula with VLT-MUSE. II. The spectroscopic Hertzsprung-Russell diagram of OB stars in NGC 2070We present the spectroscopic analysis of 333 OB-type stars extracted from VLT-MUSE observations of the central 30 × 30 pc of NGC 2070 in the Tarantula Nebula on the Large Magellanic Cloud, the majority of which are analysed for the first time. The distribution of stars in the spectroscopic Hertzsprung-Russell diagram (sHRD) shows 281 stars in theCastro, N. et al.
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42021 -
Multiplicity among the cool supergiants in the Magellanic CloudsThe characterization of multiplicity of high-mass stars is of fundamental importance to understand their evolution, the diversity of observed core-collapse supernovae and the formation of gravitational wave progenitor systems. Despite that, until recently, one of the final phases of massive star evolution - the cool supergiant phase - has receivedDorda, R. et al.
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42021 -
A dearth of young and bright massive stars in the Small Magellanic CloudContext. Massive star evolution at low metallicity is closely connected to many fields in high-redshift astrophysics, but is poorly understood so far. Because of its metallicity of ∼0.2 Z ⊙, its proximity, and because it is currently forming stars, the Small Magellanic Cloud (SMC) is a unique laboratory in which to study metal-poor massive starsSchootemeijer, A. et al.
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22021 -
The nature of VX Sagitarii. Is it a TŻO, a RSG, or a high-mass AGB star?Aims: We present a spectroscopic analysis of the extremely luminous red star VX Sgr based on high-resolution observations combined with AAVSO light curve data. Given the puzzling characteristics of VX Sgr, we explore three scenarios for its nature: a massive red supergiant (RSG) or red hypergiant (RHG), a Thorne Żytkow object, and an extremeTabernero, H. M. et al.
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22021 -
Lucky spectroscopy, an equivalent technique to lucky imaging. II. Spatially resolved intermediate-resolution blue-violet spectroscopy of 19 close massive binaries using the William Herschel TelescopeContext. Many massive stars have nearby companions. These hamper a characterization of massive stars through spectroscopy. Aims: We continue to obtain spatially resolved spectroscopy of close massive visual binaries to derive their spectral types. Methods: We used the lucky spectroscopy technique to obtain a large number of short long-slitMaíz Apellániz, J. et al.
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22021 -
2D kinematics of massive stars near the Galactic CentreThe presence of massive stars (MSs) in the region close to the Galactic Centre (GC) poses several questions about their origin. The harsh environment of the GC favours specific formation scenarios, each of which should imprint characteristic kinematic features on the MSs. We present a 2D kinematic analysis of MSs in a GC region surrounding Sgr A*Libralato, Mattia et al.
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12021 -
2D kinematics of massive stars near the Galactic CentreThe presence of massive stars (MSs) in the region close to the Galactic Centre (GC) poses several questions about their origin. The harsh environment of the GC favours specific formation scenarios, each of which should imprint characteristic kinematic features on the MSs. We present a 2D kinematic analysis of MSs in a GC region surrounding Sgr A*Libralato, Mattia et al.
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112020 -
High-resolution spectroscopic study of massive blue and red supergiants in Perseus OB1. I. Definition of the sample, membership, and kinematicsContext. The Perseus OB1 association, including the h and χ Persei double cluster, is an interesting laboratory for the investigation of massive star evolution as it hosts one of the most populous groupings of blue and red supergiants (Sgs) in the Galaxy at a moderate distance and extinction. Aims: We discuss whether the massive O-type, and bluede Burgos, A. et al.
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112020 -
The R136 star cluster dissected with Hubble Space Telescope/STIS - II. Physical properties of the most massive stars in R136We present an optical analysis of 55 members of R136, the central cluster in the Tarantula Nebula of the Large Magellanic Cloud. Our sample was observed with STIS aboard the Hubble Space Telescope, is complete down to about 40 M ☉, and includes seven very massive stars with masses over 100 M ☉. We performed a spectroscopic analysis to derive theirBestenlehner, Joachim M. et al.
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92020 -
Spectroscopic characterization of the known O-star population in Cygnus OB2. Evidence of multiple star-forming burstsContext. Cygnus OB2 provides a unique insight into the high-mass stellar content in one of the largest groups of young massive stars in our Galaxy. Although several studies of its massive population have been carried out over the last decades, an extensive spectroscopic study of the whole known O-star population in the association is still lackingBerlanas, S. R. et al.
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102020 -
CARMENES input catalogue of M dwarfs. V. Luminosities, colours, and spectral energy distributionsContext. The relevance of M dwarfs in the search for potentially habitable Earth-sized planets has grown significantly in the last years. Aims: In our on-going effort to comprehensively and accurately characterise confirmed and potential planet-hosting M dwarfs, in particular for the CARMENES survey, we have carried out a comprehensive multi-bandCifuentes, C. et al.
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102020 -
The absolute proper motions of the Arches and Quintuplet clustersArches and Quintuplet are two young, massive clusters projected near the Galactic Centre. To date, studies focused on understanding their origin have been based on proper motions (PMs) derived in the clusters' reference frames and required some assumptions about their 3D motion. In this paper, we combine public PM catalogues of these clusters withLibralato, Mattia et al.
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82020 -
An extensive spectroscopic time series of three Wolf-Rayet stars - II. A search for wind asymmetries in the dust-forming WC7 binary WR137We present the results of a 4-month, spectroscopic campaign of the Wolf-Rayet dust-making binary, WR137. We detect only small-amplitude random variability in the C III λ5696 emission line and its integrated quantities (radial velocity, equivalent width, skewness, and kurtosis) that can be explained by stochastic clumps in the wind of the WC starSt-Louis, N. et al.
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72020 -
Photometric detection of internal gravity waves in upper main-sequence stars. II. Combined TESS photometry and high-resolution spectroscopyContext. Massive stars are predicted to excite internal gravity waves (IGWs) by turbulent core convection and from turbulent pressure fluctuations in their near-surface layers. These IGWs are extremely efficient at transporting angular momentum and chemical species within stellar interiors, but they remain largely unconstrained observationallyBowman, D. M. et al.
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82020 -
Variability of OB stars from TESS southern Sectors 1-13 and high-resolution IACOB and OWN spectroscopyContext. The lack of high-precision long-term continuous photometric data for large samples of stars has impeded the large-scale exploration of pulsational variability in the OB star regime. As a result, the candidates for in-depth asteroseismic modelling have remained limited to a few dozen dwarfs. The TESS nominal space mission has surveyed theBurssens, S. et al.
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72020 -
The IACOB project. VI. On the elusive detection of massive O-type stars close to the ZAMSContext. The apparent lack of massive O-type stars near the zero-age main sequence, or ZAMS (at ages <2 Myr), is a topic that has been widely discussed in the past 40 yr. Different explanations for the elusive detection of these young massive stars have been proposed from the observational and theoretical side, but no firm conclusions have beenHolgado, G. et al.
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62020
