TY - JOUR
T1 - MHOs toward HMOs
T2 - A Search for Molecular Hydrogen Emission-Line Objects toward High-mass Outflows
AU - Wolf-Chase, Grace
AU - Arvidsson, Kim
AU - Smutko, Michael
N1 - Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/7/20
Y1 - 2017/7/20
N2 - We present the results of a narrow-band near-infrared imaging survey for Molecular Hydrogen emission-line Objects (MHOs) toward 26 regions containing high-mass protostellar candidates and massive molecular outflows. We have detected a total of 236 MHOs, 156 of which are new detections, in 22 out of the 26 regions. We use H2 2.12 μm/H2 2.25 μm flux ratios, together with morphology, to separate the signatures of fluorescence associated with photo-dissociation regions (PDRs) from shocks associated with outflows in order to identify the MHOs. PDRs have typical low flux ratios of ∼1.5-3, while the vast majority of MHOs display flux ratios typical of C-type shocks (∼6-20). A few MHOs exhibit flux ratios consistent with expected values for J-type shocks (∼3-4), but these are located in regions that may be contaminated with fluorescent emission. Some previously reported MHOs have low flux ratios, and are likely parts of PDRs rather than shocks indicative of outflows. We identify a total of 36 outflows across the 22 target regions where MHOs were detected. In over half these regions, MHO arrangements and fluorescent structures trace features present in CO outflow maps, suggesting that the CO emission traces a combination of dynamical effects, which may include gas entrained in expanding PDRs as well as bipolar outflows. Where possible, we link MHO complexes to distinct outflows and identify candidate driving sources.
AB - We present the results of a narrow-band near-infrared imaging survey for Molecular Hydrogen emission-line Objects (MHOs) toward 26 regions containing high-mass protostellar candidates and massive molecular outflows. We have detected a total of 236 MHOs, 156 of which are new detections, in 22 out of the 26 regions. We use H2 2.12 μm/H2 2.25 μm flux ratios, together with morphology, to separate the signatures of fluorescence associated with photo-dissociation regions (PDRs) from shocks associated with outflows in order to identify the MHOs. PDRs have typical low flux ratios of ∼1.5-3, while the vast majority of MHOs display flux ratios typical of C-type shocks (∼6-20). A few MHOs exhibit flux ratios consistent with expected values for J-type shocks (∼3-4), but these are located in regions that may be contaminated with fluorescent emission. Some previously reported MHOs have low flux ratios, and are likely parts of PDRs rather than shocks indicative of outflows. We identify a total of 36 outflows across the 22 target regions where MHOs were detected. In over half these regions, MHO arrangements and fluorescent structures trace features present in CO outflow maps, suggesting that the CO emission traces a combination of dynamical effects, which may include gas entrained in expanding PDRs as well as bipolar outflows. Where possible, we link MHO complexes to distinct outflows and identify candidate driving sources.
KW - ISM: jets and outflows
KW - stars: formation
KW - stars: massive
KW - stars: pre-main sequence
KW - stars: protostars
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U2 - 10.3847/1538-4357/aa762a
DO - 10.3847/1538-4357/aa762a
M3 - Article
AN - SCOPUS:85026408277
VL - 844
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 38
ER -