Volume 622, February 2019
|Number of page(s)||38|
|Section||Stellar structure and evolution|
|Published online||12 February 2019|
VISION – Vienna survey in Orion
III. Young stellar objects in Orion A⋆
Universität Wien, Institut für Astrophysik, Türkenschanzstrasse 17, 1180 Wien, Austria
2 University of Vienna, Faculty of Earth Sciences, Geography and Astronomy, Data Science at Uni Vienna, Austria
3 Radcliffe Institute for Advanced Study, Harvard University, 10 Garden Street, Cambridge, MA 02138, USA
4 Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (IEEC-UB), Martí i Franquès 1, 08028 Barcelona, Spain
5 Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS, UK
6 Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, Allée Geoffroy Saint-Hilaire, CS 50023 33615 Pessac Cedex, France
7 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB Hertfordshire, UK
8 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
9 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
10 Universidade do Porto, Dep. de Engenharia Física da Faculdade de Engenharia, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
11 Universität Wien, Fakultät für Informatik, Währinger Straße 29/S6, 1090 Wien, Austria
12 University of Milan, Department of Physics, Via Celoria 16, 20133 Milan, Italy
13 University of Vienna, Faculty of Computer Science, Data Science at Uni Vienna, Austria
Accepted: 27 September 2018
We have extended and refined 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 deg2, ∼950 pc2), 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 ∼6.4% and ∼2.3%, 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 2980 YSOs, which were classified based on the de-reddened mid-infrared spectral index into 188 protostars, 185 flat-spectrum sources, and 2607 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.
Key words: methods: observational / stars: formation / stars: pre-main sequence / ISM: clouds / infrared: stars / methods: statistical
Full Table C.1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A149
© ESO 2019
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