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Title: HERSCHEL FAR-INFRARED SPECTRAL-MAPPING OF ORION BN/KL OUTFLOWS: SPATIAL DISTRIBUTION OF EXCITED CO, H{sub 2}O, OH, O, AND C{sup +} IN SHOCKED GAS

We present ∼2' × 2' spectral-maps of Orion Becklin-Neugebauer/Kleinmann-Low (BN/KL) outflows taken with Herschel at ∼12'' resolution. For the first time in the far-IR domain, we spatially resolve the emission associated with the bright H{sub 2} shocked regions ''Peak 1'' and ''Peak 2'' from that of the hot core and ambient cloud. We analyze the ∼54-310 μm spectra taken with the PACS and SPIRE spectrometers. More than 100 lines are detected, most of them rotationally excited lines of {sup 12}CO (up to J = 48-47), H{sub 2}O, OH, {sup 13}CO, and HCN. Peaks 1/2 are characterized by a very high L(CO)/L {sub FIR} ≈ 5 × 10{sup –3} ratio and a plethora of far-IR H{sub 2}O emission lines. The high-J CO and OH lines are a factor of ≈2 brighter toward Peak 1 whereas several excited H{sub 2}O lines are ≲50% brighter toward Peak 2. Most of the CO column density arises from T {sub k} ∼ 200-500 K gas that we associate with low-velocity shocks that fail to sputter grain ice mantles and show a maximum gas-phase H{sub 2}O/CO ≲ 10{sup –2} abundance ratio. In addition, the very excited CO (J > 35) and H{sub 2}O lines reveal a hotter gas component (T {sub k} ∼ 2500 K)more » from faster (v {sub S} > 25 km s{sup –1}) shocks that are able to sputter the frozen-out H{sub 2}O and lead to high H{sub 2}O/CO ≳ 1 abundance ratios. The H{sub 2}O and OH luminosities cannot be reproduced by shock models that assume high (undepleted) abundances of atomic oxygen in the preshock gas and/or neglect the presence of UV radiation in the postshock gas. Although massive outflows are a common feature in other massive star-forming cores, Orion BN/KL seems more peculiar because of its higher molecular luminosities and strong outflows caused by a recent explosive event.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8]
  1. Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC). Sor Juana Ines de la Cruz 3, E-28049 Cantoblanco, Madrid (Spain)
  2. Centro de Astrobiología, CSIC-INTA, Ctra. de Torrejón a Ajalvir km 4, E-28850 Madrid (Spain)
  3. Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
  4. Herschel Science Center, ESA/ESAC, P.O. Box 78, Villanueva de la Cañada, E-28691 Madrid (Spain)
  5. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
  6. LERMA, UMR 8112 du CNRS, Observatoire de Paris, École Normale Supérieure, F-75014 Paris (France)
  7. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 66, Cambridge, MA 02138 (United States)
  8. RAL Space, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom)
Publication Date:
OSTI Identifier:
22364423
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON IONS; CARBON MONOXIDE; CLOUDS; DENSITY; EMISSION SPECTRA; HYDROGEN; ICE; JETS; LUMINOSITY; MAPPING; OXYGEN; PROTOSTARS; SHOCK WAVES; SPATIAL DISTRIBUTION; STARS; ULTRAVIOLET RADIATION; VELOCITY; WATER