VLA cm-wave survey of young stellar objects in the Oph A cluster: Constraining extreme UV- And X-ray-driven disk photoevaporation: A pathfinder for Square Kilometre Array studies

Research output: Contribution to journalArticle


Observations of young stellar objects (YSOs) in centimeter bands can probe the continuum emission from growing dust grains, ionized winds, and magnetospheric activity that are intimately connected to the evolution of protoplanetary disks and the formation of planets. We carried out sensitive continuum observations toward the Ophiuchus A star-forming region, using the Karl G. Jansky Very Large Array (VLA) at 10 GHz over a field-of-view of 6′ and with a spatial resolution of θmaj ×θmin ∼ 0.′′4 × 0.′′2. We achieved a 5 μJy beam-1 rms noise level at the center of our mosaic field of view. Among the 18 sources we detected, 16 were YSOs (three Class 0, five Class I, six Class II, and two Class III) and two were extragalactic candidates. We find that thermal dust emission generally contributed less than 30% of the emission at 10 GHz. The radio emission is dominated by other types of emission, such as gyro-synchrotron radiation from active magnetospheres, free-free emission from thermal jets, free-free emission from the outflowing photoevaporated disk material, and synchrotron emission from accelerated cosmic-rays in jet or protostellar surface shocks. These different types of emission could not be clearly disentangled. Our non-detections for Class II/III disks suggest that extreme UV-driven photoevaporation is insufficient to explain disk dispersal, assuming that the contribution of UV photoevaporating stellar winds to radio flux does not evolve over time. The sensitivity of our data cannot exclude photoevaporation due to the role of X-ray photons as an efficient mechanism for disk dispersal. Deeper surveys using the Square Kilometre Array (SKA) will have the capacity to provide significant constraints to disk photoevaporation.


  • A. Coutens
  • H. B. Liu
  • I. Jiménez-Serra
  • T. L. Bourke
  • J. Forbrich
  • M. Hoare
  • L. Loinard
  • L. Testi
  • M. Audard
  • P. Caselli
  • A. Chacón-Tanarro
  • C. Codella
  • J. Di Francesco
  • F. Fontani
  • M. Hogerheijde
  • D. Johnstone
  • S. Maddison
  • O. Panić
  • L. M. Pérez
  • L. Podio
  • A. Punanova
  • J. M.C. Rawlings
  • D. Semenov
  • M. Tazzari
  • J. J. Tobin
  • M. H.D. Van Der Wiel
  • H. J. Van Langevelde
  • W. Vlemmings
  • C. Walsh
  • D. Wilner
External organisations
  • University of Bordeaux
  • European Southern Observatory
  • Queen Mary University
  • SKA Organisation, UK
  • University of Hertfordshire
  • University of Leeds
  • National Autonomous University of Mexico
  • INAF - Osservatorio Astrofisico di Arcetri
  • University of Geneva
  • Max Planck Institute for Extraterrestrial Physics
  • Observatorio Astronómico Nacional (OAG-IGN)
  • University Grenoble Alpes
  • University of Victoria
  • Leiden University
  • Swinburne University of Technology
  • University of Chile
  • Ural Federal University
  • University College London
  • Max Planck Institute for Astronomy
  • National Radio Astronomy Observatory
  • Netherlands Institute for Radio Astronomy (ASTRON)
  • Joint Institute for VLBI in Europe (JIVE)
  • Chalmers University of Technology
  • Harvard–Smithsonian Center for Astrophysics
  • NRC Herzberg Institute of Astrophysics (NRC-HIA)
  • University of Amsterdam
  • Ludwig-Maximilian University of Munich
  • University of Cambridge
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology


  • Protoplanetary disks, Radio continuum: stars, Stars: activity, Stars: formation
Original languageEnglish
Article numberA58
JournalAstronomy and Astrophysics
Publication statusPublished - 2019
Publication categoryResearch