Recent Submissions

  • X-Shooting ULLYSES: Massive Stars at Low Metallicity

    Armagh Observatory and Planetarium, UK; Department of Physics & Astronomy, University of Sheffield, UK; Space Telescope Science Institute, Baltimore, USA; Centre for Astrobiology (CSIC-INTA), Torrejón de Ardoz, Madrid, Spain; Montpellier Universe and Particles Laboratory, Montpellier University, France; Las Campanas Observatory, Carnegie Observatories, Chile; Institute for Physics and Astronomy, University of Potsdam, Germany; Department of Physics, University of Montreal, Canada; Penn State Scranton, Dunmore, PA, USA; Astronomy Centre, Heidelberg University, Germany; et al. (The Messenger, 2024-03-01)
    The Hubble Space Telescope has devoted 500 orbits to observing 250 massive stars with low metallicity in the ultraviolet (UV) range within the framework of the ULLYSES program. The X-Shooting ULLYSES (XShootU) project enhances the legacy value of this UV dataset by providing high-quality optical and near-infrared spectra, which are acquired using the wide-wavelength- coverage X-shooter spectrograph at ESO's Very Large Telescope. XShootU emphasises the importance of combining UV with optical spectra for the consistent determination of key stellar parameters such as effective temperature, surface gravity, luminosity, abundances, and wind characteristics including mass-loss rates as a function of metallicity. Since uncertainties in these parameters have implications across various branches of astrophysics, the data and modelling generated by the XShootU project are poised to significantly advance our understanding of massive stars at low metallicity. This is particularly crucial for confidently interpreting James Webb Space Telescope (JWST) data of the earliest stellar generations, making XShootU a unique resource for comprehending individual spectra of low-metallicity stars.
  • Multimessenger science opportunities with mHz gravitational waves

    NASA Goddard Space Flight Center; Columbia University; Leiden University; Harvard University; The Pennsylvania State University; University of Cambridge; CITA, University of Toronto; California Institute of Technology; City University of New York/American Museum of Natural History; Princeton University; et al. (Bulletin of the American Astronomical Society, 2019-05-01)
    We review opportunities for multi-messenger science breakthroughs involving mHz gravitational waves with electromagnetic observations.
  • The VLT-FLAMES Tarantula Survey

    Armagh Observatory, College Hill, BT61 9DG, Armagh, Northern Ireland; ATC, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, UK; ARC, School of Mathematics and Physics, QUB, Belfast BT7 1NN, UK; Institute of Astrophysics, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium; Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK; -; Vink, Jorick S.; Evans, C. J.; Bestenlehner, J.; McEvoy, C.; et al. (The Lives and Death-Throes of Massive Stars, 2017-11-01)
    We present a number of notable results from the VLT-FLAMES Tarantula Survey (VFTS), an ESO Large Program during which we obtained multi-epoch medium-resolution optical spectroscopy of a very large sample of over 800 massive stars in the 30 Doradus region of the Large Magellanic Cloud (LMC). This unprecedented data-set has enabled us to address some key questions regarding atmospheres and winds, as well as the evolution of (very) massive stars. Here we focus on O-type runaways, the width of the main sequence, and the mass-loss rates for (very) massive stars. We also provide indications for the presence of a top-heavy initial mass function (IMF) in 30 Dor.
  • MOONS: The New Multi-Object Spectrograph for the VLT

    ESO; STFC, UK Astronomy Technology Centre, Royal Observatory Edinburgh, UK; Cavendish Laboratory, University of Cambridge, UK; Instituto de Astrofísica e Ciências do Espaço and Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Portugal; GEPI, Observatoire de Paris, PSL University, CNRS, France; Department of Physics, ETH Zurich, Switzerland; INAF-Osservatorio Astrofisico di Arcetri, Florence, Italy; Department of Astronomy, University of Geneva, Versoix, Switzerland; Pontificia Universidad Católica de Chile, Santiago, Chile; Department of Physics, University of Oxford, UK; et al. (The Messenger, 2020-06-01)
    MOONS is the new Multi-Object Optical and Near-infrared Spectrograph currently under construction for the Very Large Telescope (VLT) at ESO. This remarkable instrument combines, for the first time, the collecting power of an 8-m telescope, 1000 fibres with individual robotic positioners, and both low- and high-resolution simultaneous spectral coverage across the 0.64-1.8 μm wavelength range. This facility will provide the astronomical community with a powerful, world-leading instrument able to serve a wide range of Galactic, extragalactic and cosmological studies. Construction is now proceeding full steam ahead and this overview article presents some of the science goals and the technical description of the MOONS instrument. More detailed information on the MOONS surveys is provided in the other dedicated articles in this Messenger issue.
  • The Link between Hot and Cool Outflows

    Armagh Observatory and Planetarium, College Hill, BT61 9DG, Armagh, Northern Ireland,; Vink, Jorick S.; Sander, A. A. C.; Higgins, E. R.; Sabhahit, G. N. (The Origin of Outflows in Evolved Stars, 2022-01-01)
    The link between hot and cool stellar outflows is shown to be critical for correctly predicting the masses of the most massive black holes (BHs) below the so-called pair-instability supernova (PISN) mass gap. Gravitational Wave (GW) event 190521 allegedly hosted an "impossibly" heavy BH of 85 M <SUB>⊙</SUB>. Here we show how our increased knowledge of both metallicity Z and temperature dependent mass loss is critical for our evolutionary scenario of a low-Z blue supergiant (BSG) progenitor of an initially approx 100 M <SUB>⊙</SUB> star to work. We show using MESA stellar evolution modelling experiments that as long as we can keep such stars above 8000 K such low-Z BSGs can avoid strong winds, and keep a very large envelope mass intact before core collapse. This naturally leads to the Cosmic Time dependent maximum BH function below the PISN gap.