The interstellar detection of CH3NCO in Sgr B2(N)

Halfen, DeWayne T.

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https://hdl.handle.net/2142/91133 Copy

Description

Title

The interstellar detection of CH3NCO in Sgr B2(N)

Author(s)

Halfen, DeWayne T.

Contributor(s)

• Ziurys, Lucy M.
• Ilyushin, V.

Issue Date

2016-06-22

Keyword(s)

Astronomy

Abstract

• A new interstellar molecule, CH$_3$NCO (methyl isocyanate), has been detected for the first time using the 12 m telescope of the Arizona Radio Observatory (ARO). CH$_3$NCO was identified in spectra covering 68 - 116 GHz in the 3 mm segment of a broadband survey of Sgr B2(N). This study was based on previous laboratory work by Koput (1986) and new Fourier transform millimeter-wave (FTmmW) measurements performed at Arizona in the 60 - 88 GHz range. Spectroscopic constants were determined for CH$_3$NCO in a combined fit, and were used to predict other transitions at 3 mm. Thirty very favorable rotational lines (K$_a$ = 0 and K$_a$ = 1 only
• E$_u$ $<$ 60 K) originating in five consecutive transitions of CH$_3$NCO in both the A and E internal rotation states were found to be present in the Sgr B2(N) survey from 68 - 105 GHz. Emission was observed at all of the predicted frequencies, with 17 lines appearing as distinct, uncontaminated spectral features, clearly showing the classic a-type, asymmetric top pattern. The CH$_3$NCO spectra also appear to exhibit two velocity components near V$_{LSR}$ $\approx$ 62 and 73 km s$^{-1}$, both with $\Delta$V$_{1/2}$ $\approx$ 10 km s$^{-1}$, typical of most molecules in Sgr B2(N). The fractional abundances were determined to be $f$ = 7.6 x 10$^{-12}$ and 5.0 x 10$^{-12}$ for the 62 and 73 km s$^{-1}$ components, relative to H$_2$, respectively. CH$_3$NCO was recently detected in volatized material from comet 67P/Churyumov-Gerasimenko by Rosetta's Philae lander.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

En

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http://hdl.handle.net/2142/91133

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Copyright 2016 by the authors

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