view Abstract Citations (73) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Hyperfine structure of interstellar ammonia in dark clouds. Rydbeck, O. E. H. ; Sume, A. ; Hjalmarson, A. ; Ellder, J. ; Ronnang, B. O. ; Kollberg, E. Abstract Results are reported for traveling-wave maser observations of the quadrupole groups of the ammonia (J,K) equals (1,1) rotation-inversion transition (a para state) and their major magnetic hyperfine components in the dust clouds L134 N and Heiles 2. A 512-channel autocorrelation receiver with total bandwidths of 2 and 7.5 MHz was used, yielding resolutions of 7.8 and 29.3 kHz (0.10 and 0.37 km/s). Theoretically and experimentally determined line-group ratios for L134 N are found to be in excellent agreement, strongly indicating that LTE excitation conditions prevail for the observed hyperfine lines in that cloud. A strict upper limit of about 27 K is placed on the mean kinetic temperature in L134 N, the total ammonia column density is estimated to be approximately 10 to the 15th power per sq cm, and the radial velocity is reliably determined as 2.39 plus or minus 0.05 km/s. Similar values are obtained for Heiles 2. Publication: The Astrophysical Journal Pub Date: July 1977 DOI: 10.1086/182471 Bibcode: 1977ApJ...215L..35R Keywords: Ammonia; Hyperfine Structure; Interstellar Masers; Molecular Spectra; Cosmic Dust; Interstellar Gas; Quadrupoles; Radial Velocity; Thermodynamic Equilibrium; Astrophysics full text sources ADS |