Showing papers by "Charles H. Townes published in 1979"
TL;DR: In this article, the authors used infrared fine-structure line emission from compact clouds of ionized gas within Sgr A West to derive a most probable mass distribution of the clouds.
Abstract: Observations of infrared fine-structure line emission from compact clouds of ionized gas within Sgr A West are presented. These clouds have diameters of 0.1-0.5 pc, internal velocity dispersions of 100 km/s (FWHM), and line center velocities up to + or - 260 km/s. Their masses are not accurately determined but are probably between 0.1 and 10 solar masses. They are ionized by radiation like that of stars of effective temperature not greater than 35,000 K. The clouds are shown to have lifetimes of 10,000 yr and so must be generated and dissipated at a rate of a few per 1000 yr. From analysis of the distribution of the velocities of the clouds, a most probable mass distribution is derived which includes a central pointlike mass of several x 10 to the 6th solar masses in addition to several x 10 to the 6th solar masses of stars within 1 pc of the center.
172 citations
TL;DR: In this article, a hot core is found at KL, embedded in the cooler OMC-1 ridge, with only about one-tenth of the 1'.4 beam filled by regions which provide most of the emission.
Abstract: Emission from several metastable states of NH/sub 3/ is mapped in the OMC-1 and OMC-2 regions. Rotational temperatures are deduced from a comparison of the (J,K) = (1,1), (2,2), and (3,3) lines. A hot core is found at KL, embedded in the cooler OMC-1 ridge. Clumping is found to be extended over the entire OMC-1 region with only about one-tenth of the 1'.4 beam filled by regions which provide most of the emission.
54 citations
TL;DR: In this article, the fine-structure lines of forbidden O III at 88.35 microns and forbidden O I at 63.2 microns were detected in a number of sources by means of an airborne far-IR spectrometer.
Abstract: Results are presented for observations of the fine-structure lines of forbidden O III at 88.35 microns and forbidden O I at 63.2 microns in a number of sources by means of an airborne far-IR spectrometer. The sources M17, NGC 7538, and W51 are mapped in the forbidden O III line with a resolution of 1 arcmin, and the emission peak is found to coincide with the maximum radio continuum in all cases. The far-IR continuum is simultaneously mapped where possible; the continuum peak is shown to be distinct from the center of ionization in the same three sources. The forbidden O III line is also detected in W3, W49, and several positions in M42 (Orion). The forbidden O I line is detected in M17, in M42, and marginally in DR 21. An unsuccessful search for the J = 1-0 transition of HD at 112 microns in the direction of the Kleinmann-Low nebula is also reported.
23 citations
01 Dec 1979
TL;DR: A Fabry-Perot spectrometer for airborne observation of astronomical spectral lines has been designed for use in the 50 to 200μm region of the far-infrared as mentioned in this paper.
Abstract: A Fabry-Perot spectrometer for airborne observation of astronomical spectral lines has been designed for use in the 50 to 200μm region of the far-infrared. In this wavelength range lie fine structure lines from atoms and ions, and rotational transitions of light molecules such as hydrides. In a one arcminute beam a telescope will receive a far-infrared flux from the brightest fine structure lines of up to 10−15 W cm−2, with a Doppler width of 1 part in 104. The study of these lines is discussed in a companion paper [1].
15 citations
01 Dec 1979
TL;DR: The fine structure lines in the far-infrared have many simple properties that make them useful tools for diagnosing astrophysical plasmas as mentioned in this paper, such as density, elemental abundances, and ionization structure.
Abstract: Fine structure lines in the far-infrared have many simple properties that make them useful tools for diagnosing astrophysical plasmas. The line ratios are sensitive and accurate probes of density, elemental abundances, and ionization structure; also, line shapes and Doppler shifts have proven handy in studies of gross dynamics of H II regions and galaxies. These lines have several analytical and practical advantages over spectral features in the optical and radio regions for measuring certain parameters of ionized regions.
1 citations