University of Hertfordshire

From the same journal

From the same journal

By the same authors

VISION - Vienna survey in Orion. III. Young stellar objects in Orion A

Research output: Contribution to journalArticlepeer-review


  • 1810.00878v1

    Accepted author manuscript, 10.6 MB, PDF document

  • Josefa E. Großschedl
  • João Alves
  • Paula S. Teixeira
  • Hervé Bouy
  • Jan Forbrich
  • Charles J. Lada
  • Stefan Meingast
  • Álvaro Hacar
  • Joana Ascenso
  • Christine Ackerl
  • Birgit Hasenberger
  • Rainer Köhler
  • Karolina Kubiak
  • Irati Larreina
  • Lorenz Linhardt
  • Marco Lombardi
  • Torsten Möller
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Original languageEnglish
JournalAstronomy & Astrophysics
Publication statusPublished - 30 Sep 2018


We extend and refine the existing young stellar object (YSO) catalogs for the Orion A molecular cloud, the closest massive star-forming region to Earth. This updated catalog is driven by the large spatial coverage (18.3 deg^2, ~950 pc^2), seeing limited resolution (~0.7''), and sensitivity (Ks<19 mag) of the ESO-VISTA near-infrared survey of the Orion A cloud (VISION). Combined with archival mid- to far-infrared data, the VISTA data allow for a refined and more robust source selection. We estimate that among previously known protostars and pre-main-sequence stars with disks, source contamination levels (false positives) are at least ∼7% and ∼2.5%, respectively, mostly due to background galaxies and nebulosities. We identify 274 new YSO candidates using VISTA/Spitzer based selections within previously analyzed regions, and VISTA/WISE based selections to add sources in the surroundings, beyond previously analyzed regions. The WISE selection method recovers about 59% of the known YSOs in Orion A's low-mass star-forming part L1641, which shows what can be achieved by the all-sky WISE survey in combination with deep near-infrared data in regions without the influence of massive stars. The new catalog contains 2978 YSOs, which were classified based on the de-reddened mid-infrared spectral index into 188 protostars, 184 flat-spectrum sources, and 2606 pre-main-sequence stars with circumstellar disks. We find a statistically significant difference in the spatial distribution of the three evolutionary classes with respect to regions of high dust column-density, confirming that flat-spectrum sources are at a younger evolutionary phase compared to Class IIs, and are not a sub-sample seen at particular viewing angles.


38 pages, 25 figures, Accepted for publication by A&A. Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO

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