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|Title:||Laboratory measurements and astronomical search for cyanomethanimine||Authors:||Melosso, M.
|Issue Date:||2018||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||609||First Page:||A121||Abstract:||Context. C-cyanomethanimine (HNCHCN), existing in the two Z and E isomeric forms, is a key prebiotic molecule, but, so far, only the E isomer has been detected toward the massive star-forming region Sagittarius B2(N) using transitions in the radio wavelength domain. <BR /> Aims: With the aim of detecting HNCHCN in Sun-like-star forming regions, the laboratory investigation of its rotational spectrum has been extended to the millimeter-/submillimeter-wave (mm-/submm-) spectral window in which several unbiased spectral surveys have been already carried out. <BR /> Methods: High-resolution laboratory measurements of the rotational spectrum of C-cyanomethanimine were carried out in the 100-420 GHz range using a frequency-modulation absorption spectrometer. We then searched for the C-cyanomethanimine spectral features in the mm-wave range using the high-sensitivity and unbiased spectral surveys obtained with the IRAM 30-m antenna in the ASAI context, the earliest stages of star formation from starless to evolved Class I objects being sampled. <BR /> Results: For both the Z and E isomers, the spectroscopic work has led to an improved and extended knowledge of the spectroscopic parameters, thus providing accurate predictions of the rotational signatures up to 700 GHz. So far, no C-cyanomethanimine emission has been detected toward the ASAI targets, and upper limits of the column density of 10<SUP>11</SUP>-10<SUP>12</SUP> cm<SUP>-2</SUP> could only be derived. Consequently, the C-cyanomethanimine abundances have to be less than a few 10<SUP>-10</SUP> for starless and hot-corinos. A less stringent constraint, ≤10<SUP>-9</SUP>, is obtained for shocks sites. <BR /> Conclusions: The combination of the upper limits of the abundances of C-cyanomethanimine together with accurate laboratory frequencies up to 700 GHz poses the basis for future higher sensitivity searches around Sun-like-star forming regions. For compact (typically less than 1″) and chemically enriched sources such as hot-corinos, the use of interferometers as NOEMA and ALMA in their extended configurations are clearly needed. <P />The complete list of the measured transitions for Z- and E-C-cyanomethanimine is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://220.127.116.11">http://18.104.22.168</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A121">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A121||URI:||http://hdl.handle.net/20.500.12386/28367||URL:||https://www.aanda.org/articles/aa/abs/2018/01/aa31972-17/aa31972-17.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201731972||Bibcode ADS:||2018A&A...609A.121M||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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