Physical properties and evolution of Massive Stars

    General
    Description

    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.
    Principal investigator
    Project staff
    Dr.
    Gabriel Gómez Velarde

    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).

    Related publications

    • The VLT-FLAMES Tarantula Survey. XXIX. Massive star formation in the local 30 Doradus starburst
      The 30 Doradus (30 Dor) nebula in the Large Magellanic Cloud (LMC) is the brightest HII region in the Local Group and a prototype starburst similar to those found in high redshift galaxies. It is thus a stepping stone to understand the complex formation processes of stars in starburst regions across the Universe. Here, we have studied the formation
      Schneider, F. R. N. et al.

      Advertised on:

      10
      2018
      Citations
      74
    • Non-synchronous rotations in massive binary systems. HD 93343 revisited
      Context. Most massive stars are in binary or multiple systems. Several massive stars have been detected as double-lined spectroscopic binaries and among these, the OWN Survey has detected a non-negligible number whose components show very different spectral line broadening (i.e., projected rotational velocities). This fact raises a discussion about
      Putkuri, C. et al.

      Advertised on:

      10
      2018
      Citations
      8
    • An updated stellar census of the Quintuplet cluster
      Context. Found within the central molecular zone, the Quintuplet is one of the most massive young clusters in the Galaxy. As a consequence it offers the prospect of constraining stellar formation and evolution in extreme environments. However, current observations suggest that it comprises a remarkably diverse stellar population that is difficult
      Clark, J. S. et al.

      Advertised on:

      10
      2018
      Citations
      32
    • The VLT-FLAMES Tarantula Survey. XXVIII. Nitrogen abundances for apparently single dwarf and giant B-type stars with small projected rotational velocities
      Previous analyses of the spectra of OB-type stars in the Magellanic Clouds have identified targets with low projected rotational velocities and relatively high nitrogen abundances; the evolutionary status of these objects remains unclear. The VLT-FLAMES Tarantula Survey obtained spectroscopy for over 800 early-type stars in 30 Doradus of which 434
      Dufton, P. L. et al.

      Advertised on:

      7
      2018
      Citations
      24
    • Lucky Spectroscopy, an equivalent technique to Lucky Imaging. Spatially resolved spectroscopy of massive close visual binaries using the William Herschel Telescope
      Context. Many massive stars have nearby companions whose presence hamper their characterization through spectroscopy. Aims: We want to obtain spatially resolved spectroscopy of close massive visual binaries to derive their spectral types. Methods: We obtained a large number of short long-slit spectroscopic exposures of five close binaries under
      Maíz Apellániz, J. et al.

      Advertised on:

      8
      2018
      Citations
      22
    • Search for Galactic runaway stars using Gaia Data Release 1 and HIPPARCOS proper motions
      Context. The first Gaia Data Release (DR1) significantly improved the previously available proper motions for the majority of the Tycho-2 stars. Aims: We wish to detect runaway stars using Gaia DR1 proper motions and compare our results with previous searches. Methods: Runaway O stars and BA supergiants were detected using a 2D proper motion method
      Maíz Apellániz, J. et al.

      Advertised on:

      8
      2018
      Citations
      47
    • The Arches cluster revisited. II. A massive eclipsing spectroscopic binary in the Arches cluster
      We have carried out a spectroscopic variability survey of some of the most massive stars in the Arches cluster, using K-band observations obtained with SINFONI on the VLT. One target, F2, exhibits substantial changes in radial velocity (RV); in combination with new KMOS and archival SINFONI spectra, its primary component is found to undergo RV
      Lohr, M. E. et al.

      Advertised on:

      9
      2018
      Citations
      26
    • HST Astrometry in the 30 Doradus Region. II. Runaway Stars from New Proper Motions in the Large Magellanic Cloud
      We present a catalog of relative proper motions for 368,787 stars in the 30 Doradus region of the Large Magellanic Cloud (LMC), based on a dedicated two-epoch survey with the Hubble Space Telescope and supplemented with proper motions from our pilot archival study. We demonstrate that a relatively short epoch difference of three years is sufficient
      Platais, I. et al.

      Advertised on:

      9
      2018
      Citations
      16
    • Massive stars in the hinterland of the young cluster, Westerlund 2
      An unsettled question concerning the formation and distribution of massive stars is whether they must be born in massive clusters and, if found in less dense environments, whether they must have migrated there. With the advent of wide-area digital photometric surveys, it is now possible to identify massive stars away from prominent Galactic
      Drew, J. E. et al.

      Advertised on:

      10
      2018
      Citations
      29
    • Identifying two groups of massive stars aligned in the l 38° Galactic direction
      Context. Recent near-infrared data have contributed to unveiling massive and obscured stellar populations in both new and previously known clusters in our Galaxy. These discoveries have lead us to view the Milky Way as an active star-forming machine. Aims: We look for young massive cluster candidates as over-densities of OB-type stars. The first
      Ramírez Alegría, S. et al.

      Advertised on:

      6
      2018
      Citations
      0
    • Fundamental parameters of massive stars in multiple systems: The cases of HD 17505A and HD 206267A
      Context. Many massive stars are part of binary or higher multiplicity systems. The present work focusses on two higher multiplicity systems: HD 17505A and HD 206267A. Aims: Determining the fundamental parameters of the components of the inner binary of these systems is mandatory to quantify the impact of binary or triple interactions on their
      Raucq, F. et al.

      Advertised on:

      6
      2018
      Citations
      7
    • The IACOB project. V. Spectroscopic parameters of the O-type stars in the modern grid of standards for spectral classification
      Context. The IACOB and OWN surveys are two ambitious, complementary observational projects which have made available a large multi-epoch spectroscopic database of optical high resolution spectra of Galactic massive O-type stars. Aims: Our aim is to study the full sample of (more than 350) O stars surveyed by the IACOB and OWN projects. As a first
      Holgado, G. et al.

      Advertised on:

      6
      2018
      Citations
      71
    • Low-frequency photospheric and wind variability in the early-B supergiant HD 2905
      Context. Despite important advances in space asteroseismology during the last decade, the early phases of evolution of stars with masses above 15 M⊙ (including the O stars and their evolved descendants, the B supergiants) have been only vaguely explored up to now. This is due to the lack of adequate observations for a proper characterization of the
      Simón-Díaz, S. et al.

      Advertised on:

      4
      2018
      Citations
      32
    • New massive members of Cygnus OB2
      Context. The Cygnus complex is one of the most powerful star forming regions at a close distance from the Sun ( 1.4 kpc). Its richest OB association Cygnus OB2 is known to harbor many tens of O-type stars and hundreds of B-type stars, providing a large homogeneous population of OB stars that can be analyzed. Many studies of its massive population
      Berlanas, S. R. et al.

      Advertised on:

      4
      2018
      Citations
      30
    • An excess of massive stars in the local 30 Doradus starburst
      The 30 Doradus star-forming region in the Large Magellanic Cloud is a nearby analog of large star-formation events in the distant universe. We determined the recent formation history and the initial mass function (IMF) of massive stars in 30 Doradus on the basis of spectroscopic observations of 247 stars more massive than 15 solar masses (M☉). The
      Schneider, F. R. N. et al.

      Advertised on:

      1
      2018
      Citations
      185
    • Extinction Maps and Dust-to-gas Ratios in Nearby Galaxies with LEGUS
      We present a study of the dust-to-gas ratios in five nearby galaxies: NGC 628 (M74), NGC 6503, NGC 7793, UGC 5139 (Holmberg I), and UGC 4305 (Holmberg II). Using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from the Treasury program Legacy ExtraGalactic UV Survey (LEGUS) combined with archival HST/Advanced Camera for Surveys
      Kahre, L. et al.

      Advertised on:

      3
      2018
      Citations
      27
    • The Resolved Stellar Populations in the LEGUS Galaxies1
      The Legacy ExtraGalactic UV Survey (LEGUS) is a multiwavelength Cycle 21 Treasury program on the Hubble Space Telescope. It studied 50 nearby star-forming galaxies in 5 bands from the near-UV to the I-band, combining new Wide Field Camera 3 observations with archival Advanced Camera for Surveys data. LEGUS was designed to investigate how star
      Sabbi, E. et al.

      Advertised on:

      3
      2018
      Citations
      78
    • K2 photometry and HERMES spectroscopy of the blue supergiant ρ Leo: rotational wind modulation and low-frequency waves
      We present an 80-d long uninterrupted high-cadence K2 light curve of the B1Iab supergiant ρ Leo (HD 91316), deduced with the method of halo photometry. This light curve reveals a dominant frequency of frot = 0.0373 d-1 and its harmonics. This dominant frequency corresponds with a rotation period of 26.8 d and is subject to amplitude and phase
      Aerts, C. et al.

      Advertised on:

      5
      2018
      Citations
      40
    • A new method of measuring centre-of-mass velocities of radially pulsating stars from high-resolution spectroscopy
      We present a radial velocity analysis of 20 solar neighbourhood RR Lyrae and three Population II Cepheid variables. We obtained high-resolution, moderate-to-high signal-to-noise ratio spectra for most stars; these spectra covered different pulsation phases for each star. To estimate the gamma (centre-of-mass) velocities of the programme stars, we
      Britavskiy, N. et al.

      Advertised on:

      3
      2018
      Citations
      6
    • An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS). IV. Discovery of High-redshift AGB Analogs
      The survey for DUST in Nearby Galaxies with Spitzer (DUSTiNGS) identified several candidate Asymptotic Giant Branch (AGB) stars in nearby dwarf galaxies and showed that dust can form even in very metal-poor systems ({\boldsymbol{Z}}∼ 0.008 {Z}ȯ ). Here, we present a follow-up survey with WFC3/IR on the Hubble Space Telescope (HST), using filters
      Boyer, M. L. et al.

      Advertised on:

      12
      2017
      Citations
      45

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