Imperial College London
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Dr Clements

Faculty of Natural Sciences, Department of Physics

Reader in Astrophysics
 
 
 
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Contact

 

+44 (0)20 7594 7693d.clements

 
 
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Location

 

1011Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Drabek-Maunder:2019:10.1017/S1473550417000428,
author = {Drabek-Maunder, E and Greaves, J and Fraser, HJ and Clements, DL and Alconcel, LN},
doi = {10.1017/S1473550417000428},
journal = {International Journal of Astrobiology},
pages = {25--32},
title = {Ground-based detection of a cloud of methanol from Enceladus: when is a biomarker not a biomarker?},
url = {http://dx.doi.org/10.1017/S1473550417000428},
volume = {18},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Saturn's moon Enceladus has vents emerging from a sub-surface ocean, offering unique probes into the liquid environment. These vents drain into the larger neutral torus in orbit around Saturn. We present a methanol (CH3OH) detection observed with IRAM 30-m from 2008 along the line-of-sight through Saturn's E-ring. Additionally, we also present supporting observations from the Herschel public archive of water (ortho-H2O; 1669.9 GHz) from 2012 at a similar elongation and line-of-sight. The CH3OH 5(1,1)-4(1,1) transition was detected at 5.9σ confidence. The line has 0.43 km s−1width and is offset by +8.1 km s−1in the moon's reference frame. Radiative transfer models allow for gas cloud dimensions from 1750 km up to the telescope beam diameter ~73 000 km. Taking into account the CH3OH lifetime against solar photodissociation and the redshifted line velocity, there are two possible explanations for the CH3OH emission: methanol is primarily a secondary product of chemical interactions within the neutral torus that: (1) spreads outward throughout the E-ring or (2) originates from a compact, confined gas cloud lagging Enceladus by several km s−1. We find either scenario to be consistent with significant redshifted H2O emission (4σ) measured from the Herschel public archive. The measured CH3OH:H2O abundance (>0.5%) significantly exceeds the observed abundance in the direct vicinity of the vents (~0.01%), suggesting CH3OH is likely chemically processed within the gas cloud with methane (CH4) as its parent species.
AU  - Drabek-Maunder,E
AU  - Greaves,J
AU  - Fraser,HJ
AU  - Clements,DL
AU  - Alconcel,LN
DO  - 10.1017/S1473550417000428
EP  - 32
PY  - 2019///
SN  - 1473-5504
SP  - 25
TI  - Ground-based detection of a cloud of methanol from Enceladus: when is a biomarker not a biomarker?
T2  - International Journal of Astrobiology
UR  - http://dx.doi.org/10.1017/S1473550417000428
UR  - http://hdl.handle.net/10044/1/60479
VL  - 18
ER  -
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