Showing papers by "Charles H. Townes published in 1985"
TL;DR: In this paper, the 158 microns fine-structure line of C(+) toward the nuclei of six gas-rich galaxies was observed and compared with observations of the CO J = 1-0 and H I 21 cm lines, observations of far IR continuum emission, and observations of forbidden C II emission with the Galaxy.
Abstract: Observations of the 158 microns fine-structure line of C(+) toward the nuclei of six gas-rich galaxies are presented. The observations are compared with observations of the CO J = 1-0 and H I 21 cm lines, observations of far-IR continuum emission, and observations of forbidden C II emission with the Galaxy. The forbidden C II line comes from dense, warm gas in UV-illuminated photodissociation regions at the surfaces of molecular clouds. This line is probably optically thin in all but the brightest of galactic sources. The variation of forbidden C II brightness from source to source and its ratio to the integrated infrared continuum intensity agree well with the theoretical prediction that UV absorption by dust controls the C(+) column density. The forbidden C II line is a tracer of molecular clouds, especially those near intense sources of UV radiation.
239 citations
TL;DR: In this paper, far-infrared C(+) and O(0) fine-structure lines and the first detection of CO and OH rotational line emission and OH absorption toward the Galactic center are reported.
Abstract: The mapping of far-infrared C(+) and O(0) fine-structure lines and the first detection of far-infrared CO and OH rotational line emission and OH absorption toward the Galactic center are reported. These measurments are compared with far-infrared and radio continuum maps, with recent observations of the 12.8 micron forbidden Ne II line, and with measurements of CO 2.6 mm emission and H I 21 cm absorption. The new observations clearly show that there is a 10 pc diameter neutral gas disk or torus of several times 10,000 solar masses surrounding the inner ionized cavity. The disk has an inner radius of 1.7 pc, is inclined by about 20 deg to the Galactic plane, and may be quite thin. The atomic gas in the neutral disk is dense and fills less than 10 percent of the volume. The disk rotates about the Galactic center about an axis remarkably similar to that of the Galactic rotation at much larger scales.
129 citations
TL;DR: In this article, the far infrared rotational emission lines are observed to have velocity widths of Del V approx. 20 to 30 km/sec, somewhat less than either the 2 micro H sub 2 lines or the high velocity plateau component of the millimeter wave CO lines seen in this object.
Abstract: Observations of far infrared rotational emission lines which arise in the shocked gas associted with Orion-Kl are presented, including detections of the CO J = 34 yields 33, J = 31 yields 30, J = 26 yields 25, and OH sup 2 PI sub (3/2) J sup P = 7/2(-) yields 5/2(+) emission lines, as well as improved measurements of the CO J = 22 yields 21 and OH sup 2 PI sub (3/2) J = 5/2 yields 3/2 lines. These lines are observed to have velocity widths of Del V approx. 20 to 30 km/sec, somewhat less than either the 2 micro H sub 2 lines or the high velocity plateau component of the millimeter wave CO lines seen in this object. An H sub 2 column density of aprox. 3 x 10 to the 21st power, a total mass of approx. 1 solar mass and characteristic temperature and density T approx. 750 K and approx. 2 x 10 to the 6th power per cu cm can be derived from the CO intensities. The density is too low by at least an order of magnitude for the observed infrared H sub 2 and far infrared CO emission to bemore » accounted for by a purely hydrodynamic shock, and support is lent to hydromagnetic shock models. From the present measurements, the relative abundance of CO is estimated to be CO H sub 2 = 1.2 x .0001, corresponding to 20 percent of the cosmic abundance of C existing in the form of CO. The average relative abundance of OH in the shocked gas is O/H sub 2 or = 5 x 10 to the -7th power. An upper limit to the intensity of the HD J - 1 yields 0 line is used to derive an upper limit of tau or = 3 for the D/H relative abundance in the Orion cloud core. 61 references.« less
63 citations
01 Sep 1985
TL;DR: In this article, the far infrared rotational emission lines are observed to have velocity widths of Del V approx. 20 to 30 km/sec, somewhat less than either the 2 micro H sub 2 lines or the high velocity plateau component of the millimeter wave CO lines seen in this object.
Abstract: Observations of far infrared rotational emission lines which arise in the shocked gas associated with Orion-Kl are presented, including detections of the CO J = 34 yields 33, J = 31 yields 30, J = 26 yields 25, and OH sup 2 PI sub (3/2) J sup P = 7/2(-) yields 5/2(+) emission lines, as well as improved measurements of the CO J = 22 yields 21 and OH sup 2 PI sub (3/2) J = 5/2 yields 3/2 lines. These lines are observed to have velocity widths of Del V approx. 20 to 30 km/sec, somewhat less than either the 2 micro H sub 2 lines or the high velocity plateau component of the millimeter wave CO lines seen in this object. An H sub 2 column density of approx. 3 x 10 to the 21st power, a total mass of approx. 1 solar mass and characteristic temperature and density T approx. 750 K and approx. 2 x 10 to the 6th power per cu cm can be derived from the CO intensities. The density is too low by at least an order of magnitude for the observed infrared H sub 2 and far infrared CO emission to be accounted for by a purely hydrodynamic shock, and support is lent to hydromagnetic shock models. From the present measurements, the relative abundance of CO is estimated to be CO H sub 2 = 1.2 x .0001, corresponding to 20% of the cosmic abundance of C existing in the form of CO. The average relative abundance of OH in the shocked gas is O/H sub 2 or = 5 x 10 to the -7th power. An upper limit to the intensity of the HD J = 1 yields 0 line is used to derive an upper limit of tau or = 3 for the D/H relative abundance in the Orion cloud core.
51 citations
TL;DR: In this paper, the mass distribution at the center of the Galaxy is more concentrated than a spherical isothermal stellar cluster, which is consistent with a cluster where stellar density decreases with radius (R) at least as fast as R to the -2.7.
Abstract: New infrared and submillimeter spectroscopic measurements of the gas dynamics in the central 10 pc of the Galaxy make a convincing case that the mass distribution at the center of the Galaxy is more concentrated than a spherical isothermal stellar cluster. The measurements fit a point mass of about 4 million solar masses, but are also consistent with a cluster where stellar density decreases with radius (R) at least as fast as R to the -2.7, or a combination of a point mass and a stellar cluster. The dynamical information combined with previous 2-micron observations favor a large point mass, which is presumably a massive black hole.
23 citations
TL;DR: The spatial distribution of 10 micron continuum flux around the supergiant star Alpha Orionis was measured on two occasions separated by an interval of 1 yr as discussed by the authors, and a significant change in the infrared radiation pattern on the subarcsecond scale was observed.
Abstract: The spatial distribution of 10 micron continuum flux around the supergiant star Alpha Orionis was measured on two occasions separated by an interval of 1 yr A significant change in the infrared radiation pattern on the subarcsecond scale was observed This change cannot be explained plausibly by macroscopic motion but may be due to a change in the physical properties of the circumstellar dust
8 citations