Cernicharo, J;
Goicoechea, JR;
Daniel, F;
Lerate, MR;
Barlow, MJ;
Swinyard, BM;
van Dishoeck, EF;
... Yates, J; + view all
(2006)
The water vapor abundance in Orion KL outflows.
The Astrophysical Journal Letters
, 649
(1)
L33-L36.
10.1086/508259.
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Abstract
We present the detection and modeling of more than 70 far-IR pure rotational lines of water vapor, including the 18O and 17O isotopologues, toward Orion KL. Observations were performed with the Long Wavelength Spectrometer in Fabry-Pérot mode (λ/Δλ ~ 6800-9700) on board the Infrared Space Observatory between ~43 and 197 μm. The water line profiles evolve from P Cygni-type profiles (even for the Himg1.gifO lines) to pure emission at wavelengths above ~100 μm. We find that most of the water emission/absorption arises from an extended flow of gas expanding at 25 ± 5 km s-1. Nonlocal radiative transfer models show that much of the water excitation and line profile formation is driven by the dust continuum emission. The derived beam-averaged water abundance is (2-3) × 10-5. The inferred gas temperature Tk = 80-100 K suggests that (1) water could have been formed in the "plateau" by gas-phase neutral-neutral reactions with activation barriers if the gas was previously heated (e.g., by shocks) to ≥500 K, and/or (2) H2O formation in the outflow is dominated by in situ evaporation of grain water-ice mantles, and/or (3) H2O was formed in the innermost and warmer regions (e.g., the hot core) and was swept up in ≈1000 yr, the dynamical timescale of the outflow.
| Type: | Article |
|---|---|
| Title: | The water vapor abundance in Orion KL outflows |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1086/508259 |
| Publisher version: | https://doi.org/10.1086/508259 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Computer Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10095564 |
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