Observations and Analysis of Absorption Lines including J = K Rotational Levels of CH3CN: The Envelope of Sagittarius B2(M)

Abstract

Molecules in diffuse and translucent clouds experience cooling as a result of radiation and less excitation from collisions. However, a rotation around a molecular axis of acetonitrile, CH3CN, cannot be cooled by radiation, causing rotational populations to concentrate at the J = K levels. We aim to search for absorption lines of CH3CN having J = K level concentrations in diffuse and translucent clouds. The JK = 43-33 transition at 73.6 GHz was investigated toward Sgr B2(M) in the Galactic Center region and other sources, using the Nobeyama 45 m telescope. Based on the detected absorption lines toward Sgr B2(M), a radiation temperature of 2.8 +/- 0.5 K, kinetic temperature of 88 +/- 29 K, and column density of (1.35 +/- 0.14) x 10^14 cm-2 were derived for this molecule, revealing extremely concentrated J = K levels due to the lower excitation temperature and the higher kinetic temperature. The absorption lines occurred at a velocity of 64 km s-1. The results confirm that CH3CN with J = K level concentrations exists in the envelope of Sgr B2(M).

References in corpus (27)

• An atomic and molecular database for analysis of submillimetre line observations
• Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)
• 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
• Discovery of the Interstellar Chiral Molecule Propylene Oxide (CH${}_3$CHCH${}_2$O)
• The largest oxigen bearing organic molecule repository
• Identification of more interstellar C60+ bands
• A New Reference Chemical Composition for TMC-1
• Detection of E-cyanomethanimine towards Sagittarius B2(N) in the Green Bank Telescope PRIMOS Survey
• The Detection of Interstellar Ethanimine (CH3CHNH) from Observations taken during the GBT PRIMOS Survey
• Organic Molecules in the Galactic Center. Hot Core Chemistry without Hot Cores
• Submillimeter absorption from SH+, a new widespread interstellar radical, 13CH+ and HCl
• Detection of hydrogen fluoride absorption in diffuse molecular clouds with Herschel/HIFI: a ubiquitous tracer of molecular gas
• Digital Spectro-Correlator System for the Atacama Compact Array of the Atacama Large Millimeter/submillimeter Array
• A spectral survey of the Star Forming Core of the Orion Nebula from 455 -- 507 GHz
• Anomalous Diffuse Interstellar Bands in the Spectrum of Herschel 36. II. Analysis of Radiatively Excited CH+, CH, and DIBs
• Imaging diffuse clouds: Bright and dark gas mapped in CO
• The abundance of C3H2 and other small hydrocarbons in the diffuse interstellar medium
• Complex organic molecules in diffuse clouds along the line of sight to Sgr B2
• An ATCA Survey of Sagittarius~B2 at 7~mm: Chemical Complexity Meets Broadband Interferometry
• Chemical complexity in local diffuse and translucent clouds: ubiquitous l-C3H and CH3CN, a detection of HC3N and an upper limit on the abundance of CH2CN
• Widespread Rotationally-Hot Hydronium Ion in the Galactic Interstellar Medium
• Small-scale physical and chemical structure of diffuse and translucent molecular clouds along the line of sight to Sgr B2
• Physical and chemical differentiation of the luminous star-forming region W49A - Results from the JCMT Spectral Legacy Survey
• The physical and chemical structure of Sagittarius B2. III. Radiative transfer simulations of the hot core SgrB2(M) for methyl cyanide
• The 2006 Radio Outburst of a Microquasar Cyg X-3: Observation and Data
• Dense and diffuse gas in dynamically active clouds
• Laboratory Optical Spectroscopy of Thiophenoxy Radical and Its Profile Simulation as a Diffuse Interstellar Band Based on Rotational Distribution by Radiation and Collisions

Cited by in corpus (1)

• Herschel observations of extraordinary sources: Full Herschel/HIFI molecular line survey of Sagittarius B2(M)