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Shocks and UV radiation around low-mass protostars: the Herschel-PACS legacy

Published online by Cambridge University Press:  04 September 2018

Agata Karska ,
Michael J. Kaufman ,
Lars E. Kristensen ,
Ewine F. van Dishoeck  and
WISH, DIGIT, and WILL teams
Agata Karska
Affiliation:
Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun, Poland email: agata.karska@umk.pl Max-Planck Institut für Extraterrestrische Physik (MPE), Giessenbachstr. 1, D-85748 Garching, Germany Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
Michael J. Kaufman
Affiliation:
Department of Physics and Astronomy, San Jose State University, One Washington Square, San Jose, CA 95192-0106, USA
Lars E. Kristensen
Affiliation:
Centre for Star and Planet Formation, Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark
Ewine F. van Dishoeck
Affiliation:
Max-Planck Institut für Extraterrestrische Physik (MPE), Giessenbachstr. 1, D-85748 Garching, Germany Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
WISH, DIGIT, and WILL teams
Affiliation:
Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun, Poland email: agata.karska@umk.pl Max-Planck Institut für Extraterrestrische Physik (MPE), Giessenbachstr. 1, D-85748 Garching, Germany Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands Department of Physics and Astronomy, San Jose State University, One Washington Square, San Jose, CA 95192-0106, USA Centre for Star and Planet Formation, Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark
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Abstract

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Far-infrared spectroscopy reveals gas cooling and its underlying heating due to physical processes taking place in the surroundings of protostars. These processes are reflected in both the chemistry and excitation of abundant molecular species. Here, we present the Herschel-PACS far-IR spectroscopy of 90 embedded low-mass protostars from the WISH (van Dishoeck et al. 2011), DIGIT (Green et al. 2013), and WILL surveys (Mottram et al. 2017). The 5 × 5 spectra covering the ∼50″ × 50″ field-of-view include rotational transitions of CO, H2O, and OH lines, as well as fine-structure [O I] and [C II] in the ∼50-200 μm range. The CO rotational temperatures are typically ∼300 K, with some sources showing additional components with temperatures as high as ∼1000 K. The H2O / CO and H2O / OH flux ratios are low compared to stationary shock models, suggesting that UV photons may dissociate some H2O and decrease its abundance. Comparison to C shock models illuminated by UV photons show a good agreement between the line emission and the models for pre-shock densities of 105 cm−3 and UV fields 0.1-10 times the interstellar value. The far-infrared molecular and atomic lines are the unique diagnostic of shocks and UV fields in deeply-embedded sources.

Keywords

Young stellar objectsoutflowsjetsshocks
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S332: Astrochemistry VII: Through the Cosmos from Galaxies to Planets , March 2017 , pp. 225 - 227
Copyright
Copyright © International Astronomical Union 2018 

References

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