Research ArticleASTRONOMY

Ethyl alcohol and sugar in comet C/2014 Q2 (Lovejoy)

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Science Advances  23 Oct 2015:
Vol. 1, no. 9, e1500863
DOI: 10.1126/sciadv.1500863
  • Fig. 1 Spectra of organics in comet C/2014 Q2 (Lovejoy).

    The observations were obtained with the IRAM 30m radio telescope in the 211–272 GHz band between 13 and 25 January 2015. The velocity scale is in the nucleus rest frame. Intensity is given in the main beam temperature scale. Spectra, from top left, are glycolaldehyde (CH2OHCHO, average of two lines), ethyl alcohol (ethanol, C2H5OH, average of 13 lines), aGg′ ethylene glycol [(CH2OH)2, average of 14 lines], methyl formate (HCOOCH3, average of two groups of blends of several lines, whose positions are marked by blue arrows), formic acid (HCOOH, average of six lines), acetaldehyde (CH3CHO, average of 40 lines), isocyanic acid [HNCO(110,11–100,10) line at 241.774 GHz], and formamide (NH2CHO, average of 10 lines). The signal-to-noise ratio is 6 for glycolaldehyde, 10 for ethanol, and higher than 7 for the other molecules.

  • Fig. 2 Abundances of complex organics in comets and protostars.

    The abundances measured in comets Lovejoy (Table 1) and Hale-Bopp (table S2) are compared with those measured in the low-mass protostar IRAS 16293-2422(B) (19, 33) and in the high-mass protostar Orion-KL (18) and with results from chemical modeling in a protoplanetary disk (25). Abundances are given relative to CH3OH, the most abundant organic molecule in these sources. H2CO values may be less relevant because, for comets, a significant fraction is released from grains (34), whereas for IRAS 16293-2422, the plotted value pertains to the sum of the contributions to the two components A and B of the binary source. For CH2CO, the black triangle is a 3σ upper limit obtained in comet Lovejoy.

  • Table 1 Abundance of molecules detected in comet Lovejoy.

    Abundances relative to water of the 21 molecules detected in comet Lovejoy are based on the average of production rate ratios for the 13–16 and 23–25 January periods. The uncertainty on the abundances, taking into account all sources of errors, including uncertainty on the water production rate, is below 20%, except for NS for which it is 30% (4σ detection).

    Abundances relative to water (%)
    CHO moleculesNitrogenous moleculesSulfurated molecules
    CO1.8HCN0.09H2S0.5
    H2CO0.3HNC0.004OCS0.034
    CH3OH2.4HNCO0.009H2CS0.013
    HCOOH0.028CH3CN0.015CS0.043
    (CH2OH)20.07HC3N0.002SO0.038
    HCOOCH30.08NH2CHO0.008NS0.006
    CH3CHO0.047
    CH2OHCHO0.016
    C2H5OH0.12

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/1/9/e1500863/DC1

    Table S1. Observed strongest lines and production rates.

    Table S2. Abundances relative to water.

    Fig. S1. Rotational diagram of the methanol lines observed between 248 and 256 GHz.

    Fig. S2. Rotational diagram of the methanol lines observed around 242 GHz.

    Fig. S3. Water production rate: OH and H216O observations.

  • Supplementary Materials

    This PDF file includes:

    • Table S1. Observed strongest lines and production rates.
    • Table S2. Abundances relative to water.
    • Fig. S1. Rotational diagram of the methanol lines observed between 248 and 256 GHz.
    • Fig. S2. Rotational diagram of the methanol lines observed around 242 GHz.
    • Fig. S3. Water production rate: OH and H216O observations.

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