On Ethylene glycol in the ISM

There is a report in the literature on detection of ethanediol, aka ethylene glycol, or briefly glycol, in Sgr B2(N-LMH):
J. M. Hollis, F. J. Lovas, P. R. Jewell, and L. H. Coudert,
Interstellar Antifreeze: Ethylene Glycol
Astrophys. J. 571, L59–L62 (2002).
Because of the small number of lines and possible line overlap the detection should be viewed with some caution by itself.

More recently, two transition with complex velocity components have been detected in the centimeter range toward Sgr B2(N-LMH) employing the GBT:
J. M. Hollis,
Complex Molecules and the GBT: Is Isomerism the Key ?,
Contribution at the IAU Symposium 231, Astrochemistry throughout the Universe, Asilomar, CA.
While it is hard to say that the detection is beyond doubt, these two lines render the detection quite secure – mainly because the line density at these lower frequencies is fairly small.

The molecule was also detected in three Galactic center molecular clouds which have low dust temperatures (10–20 K), even lower rotational temperatures (around 10 K), which are moderately dense (a few tenthousand molecules per cubic centimeter), but which are kinetically moderately warm (about 100 K or more). Two transitions were detected with the 100 m GBT telescope between 13 and 23 GHz by
M. A. Requena-Torres, J. Martín-Pintado, S. Martín, and M. R. Morris,
The Galactic Center: The Largest Oxygen-bearing Organic Molecule Repository
Astrophys. J. 672, 352–360 (2008).
The column density relative to methanol is reasonable. Considering also the low rotational temperature, the detection is probably fairly secure even though only two transitions were detected.

A. J. Maury, A. Belloche, Ph. André, S. Maret, F. Gueth, C. Codella, S. Cabrit, L. Testi, and S. Bontemps
reported on
First results from the CALYPSO IRAM-PdBI survey. II. Resolving the hot corino in the Class 0 protostar NGC 1333-IRAS2A
Astron. Astrophys. 563, L2 (2014).
Ethanediol was among the molecules identified unambiguously in several transitions between 216.8 and 220.5 GHz.

A. Fuente, J. Cernicharo, P. Caselli, C. McCoey, D. Johnstone, M. Fich, T. van Kempen, Aina Palau, U.A. Yildiz, B. Tercero, and A. López
reported on
The hot core towards the intermediate mass protostar NGC7129 FIRS 2: Chemical similarities with Orion KL
Astron. Astrophys. 568, A65 (2014).
Several transitions of ethanediol were detected in a line survey with PdBI covering 218.2 to 221.8 GHz.

N. Brouillet, D. Despois, X.-H. Lu, A. Baudry, J. Cernicharo, D. Bockelée-Morvan, J. Crovisier, and N. Biver
reported on
Antifreeze in the hot core of Orion – First detection of ethylene glycol in Orion-KL
Astron. Astrophys. 576, A129 (2015).
A large number of unblended or slightly blended transitions of ethanediol were detected in an ALMA-SV line survey coverning 213.715 to 246.627 GHz.

J. K. Jørgensen, M. H. D. van der Wiel, A. Coutens, J. M. Lykke, H. S. P. Müller, E. F. van Dishoeck, H. Calcutt, P. Bjerkeli, T. L. Bourke, M. N. Drozdovskaya, C. Favre, E. C. Fayolle, R. T. Garrod, S. K. Jacobsen, K. I. Öberg, M. V. Persson, and S. F. Wampfler
reported on
The ALMA Protostellar Interferometric Line Survey (PILS): First Results from an Unbiased Submillimeter Wavelength Line Survey of the Class 0 Protostellar Binary IRAS 16293–2422 with ALMA,
Astron. Astrophys. 595, Art. No. A117 (2016).
The authors detect ethanediol unambiguously in this source and the higher energy gGg' conformer for the first time unambiguously in the ISM. There were tentative reports in both instances.


Contributor(s): H. S. P. Müller; 12, 2005; 07, 2012; 04, 2015; 11, 2016