The complexity of Orion: an ALMA view. II. gGg'-Ethylene Glycol and Acetic Acid

Continuum emission at 1.3mm (color) overlaid with the HCOOCH3 (write contours) emission at 218298 MHz. Positions of the sources analysed in our Paper I are also given.

We report the first detection and high angular resolution (1.8" × 1.1") imaging of acetic acid (CH3COOH) and gGg′--ethylene glycol (gGg′(CH2OH)2) towards the Orion Kleinmann--Low nebula.

The observations were carried out at ∼1.3mm with ALMA during the Cycle~2. A notable result is that the spatial distribution of the acetic acid and ethylene glycol emission differs from that of the other O-bearing molecules within Orion-KL. Indeed, while the typical emission of O-bearing species harbors a morphology associated with a "V-shape" linking the Hot Core region to the Compact Ridge (with an extension towards the BN object), that of acetic acid and ethylene glycol mainly peaks at about 2" southwest from the hot core region (near sources I and n).

We find that the measured CH3COOH:aGg′(CH2OH)2 and CH3COOH:gGg′(CH2OH)2 ratios differ from the ones measured towards the low-mass protostar IRAS 16293--2422 by more than one order of magnitude. Our best hypothesis to explain these findings is that CH3COOH, aGg′(CH2OH)2 and gGg′(CH2OH)2 are formed on the icy-surface of grains and then released into the gas-phase, via co-desorption with water, due to a bullet of matter ejected during the explosive event that occurred in the heart of the Nebula about 500-700 years ago.

Cécile Favre, Laurent Pagani, Paul Goldsmith, Edwin Bergin, Miguel Carvajal, Isabelle Kleiner, Gary Melnick, Ron Snell
(Submitted on 6 Jul 2017)

Comments: Accepted for publication in Astronomy and Astrophysics, section 1. Letters to the Editor
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:1707.01741 [astro-ph.GA] (or arXiv:1707.01741v1 [astro-ph.GA] for this version)
Submission history
From: Cecile Favre [view email]
[v1] Thu, 6 Jul 2017 12:10:49 GMT (10032kb,D)
https://arxiv.org/abs/1707.01741
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