Publication Abstracts

Cummins et al. 1986

Cummins, S.E., R.A. Linke, and P. Thaddeus, 1986: A survey of the millimeter-wave spectrum of Sagittarius B2. Astrophys. J. Supp. Ser., 60, 819-878, doi:10.1086/191102.

More than 60% of the millimeter-wave spectrum between 70 and 150 GHz of the giant Sgr B2 molecular cloud was surveyed with the AT&T Bell Laboratories 7 m telescope at a spectral resolution of 1 MHz. All observations were at the OH position α(1950) = 17h44mlls, δ(1950) = -28°22'301"; the angular resolution varied from 2.9' at 72 GHz to 1.5' at 143 GHz. The sensitivity of the survey is generally higher than previous spectral observations of this source: the channel-to-channel rms noise in corrected antenna temperature typically lies between 0.015 and 0.06 K but is somewhat irregular. For the most part, the sensitivity below 80 GHz is lower than above. Selected frequencies were observed for as many as 5 hours in order to search for particular molecular lines. The number of spectral lines in the survey is not precisely defined, many being at the limit of detection. The 457 lines cataloged are real or very probably so, but the number of marginal features may be as large. Of the 457 lines, 31 remain unidentified. More than 300 lines are transitions of 21 molecules: SO, OCS, SO2, HNCS, H2CS, HNCO, NH2CN, H2CCO, HC3N, NH2CHO, CH3CN, CH3SH, CH3OH, CH2CHCN, HQN, CH3CHO, CHCCH, HCOOCH3, CH3CH2CN, CH3CH2OH, and CH3OCH3, for which column densities and (excepting CH3CCH) rotational temperatures are estimated. Since the column densities were calculated from data from a single well-calibrated telescope, comparisons among them can be usefully made. The kinetic temperature of the source is estimated to be approximately 85 K, but most rotational temperatures were found to be subkinetic (between 10 and 30 K), indicating insufficient H, to thermalize the molecules. The high-energy transitions of CH3OH, HNCO, and SO, and the detectability of vibrationally excited HC3N and CH3CN offer evidence for the existence of hot spots within the source.

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BibTeX Citation

  author={Cummins, S. E. and Linke, R. A. and Thaddeus, P.},
  title={A survey of the millimeter-wave spectrum of Sagittarius B2},
  journal={Astrophysical Journal Supplement Series},

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RIS Citation

ID  - cu07000g
AU  - Cummins, S. E.
AU  - Linke, R. A.
AU  - Thaddeus, P.
PY  - 1986
TI  - A survey of the millimeter-wave spectrum of Sagittarius B2
JA  - Astrophys. J. Supp. Ser.
JO  - Astrophysical Journal Supplement Series
VL  - 60
SP  - 819
EP  - 878
DO  - 10.1086/191102
ER  -

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