# R. W. Wilson's research while affiliated with Bell Biosystems, Inc. and other places

## Publications (121)

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The authors apply a multiscale transform analysis to 13CO maps of the Perseus region and compare it to infrared cirrus emission.
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We present a galactic survey which to date consists of 73,000 positions covering –5 < l < 122, –1 < b < 1 , observed in the J=1 0 line of 13CO to an rms noise level of 0.15 K in 0.68 km s–1 channels, using the 7 m antenna at Crawford Hill. It is shown that the internal velocity dispersions of molecular clouds tend to vary inversely with galactocent...
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We have mapped a sample of Southern Hemisphere HII regions in 492 GHz atomic carbon (CI) emission using the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO). Our sample consists of 12 HII regions from the Caswell and Haynes (1987) radio recombination line catalogue. These sources are chosen to be compact and isolated. All sources h...
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We report observations of the (3) P_1->(3) P_0 fine structure transition of neutral carbon ([C I], lambda =609\ mu m) and the J=4->3 rotational transition of CO (lambda =652\ mu m) on the Large Magellanic Cloud. These measurements were performed using the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) during the 1995, 1996 and 19...
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We present the results of a study of atomic carbon ({() 3P_1 ->() 3P_0}) emission from Southern Hemisphere H \ II regions using the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO). One part of our H \ II region sample consists of 49 compact, relatively isolated members of the Wilson et al. (1970) hydrogen radio recombination line...
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A coarsely-sampled map of the region \| l \| < 2, \| b \| < 0.1 has been made in the 492 GHz (3}P_{1) - (3}P_{0) transition of [C I] with the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO). The distribution of [C I] emission is similar on the large scale to that of CO. Systematic differences between [C I] and CO emissivities in G...
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We have imaged the CO 4-3 line, the dominant coolant of the dense molecular interstellar medium, from the Galactic Center region, between l=-3 to 4 degrees and b= -1 to 1 degrees. We detect bright CO 4-3 emission from the well-known Galactic Center clouds Sgr A, Sgr B, Sgr C, and Sgr D. We compare the CO 4-3 intensities with CO 1-0, C18O 1-0, HCN 1...
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This paper presents a study of a dense molecular region, NGC 1333, and the relationship of the embedded infrared sources and young stellar objects to the structure of its molecular core. We use 13CO and C18O J=1→0 and J=2→1 observations, along with those of CS J = 2 → 1 to characterize the structure of the core, calculate densities and masses. We f...
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This paper presents a study of a dense molecular region, NGC 1333, and the relationship of the embedded infrared sources and young stellar objects to the structure of its molecular core. We use ^13^CO and C^18^O J=1->0 and J=2->1 observations, along with those of CS J=2->1 to characterize the structure of the core, calculate densities and masses. W...
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The sky north of declination -40° was observed in the 21cm line of atomic hydrogen with the FWHM=2° beam of the 20 foot horn reflector at AT&T Bell Laboratories, Crawford Hill. The survey covers a velocity range of 654km/s centered on the Galactic standard of rest, with 5.3km/s wide filters. This survey is distinguished by its sensitivity to low su...
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Observations were made as drift scans along even declinations between -40 deg. and +90 deg. at the epoch (1981) of the observations. The horn antenna has a FWHM beam size of 2 deg. at 21 cm. The average rms noise of spectra taken at all declinations is 0.017 K in 5.2 km/s wide channels, although in some cases baseline problems make the survey unrel...
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We present an analysis of density, temperature, and excitation conditions in a one half square degree region around BN/KL in Orion A using new C(O-l8) J = 1 yields 0 and J = 2 yields 1 data. This paper extends a previous study of Orion A, based on a multitransition analysis of (C-13)O, to the optically thinner C(O-18) species that traces better the...
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This survey consists of H I 21-cm spectra covering galactic latitudes |b|>10degrees, North of Declination -40deg, observed with the 20-foot horn reflector at AT&T Bell Laboratories, Crawford Hill. The instrument beam is 2° (FWHM). The data consist of 124-channel profiles sorted in Galactic latitude and longitude; each channel has a width of 5.3km/s...
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A tentative detection of the J = 1 - 0 emission line of (C-13)O has been obtained with SEST from a 24.4 hour integration. The velocity resolution used was 0.23 km/s and the FWHP beamwidth was 45 arcsec. If the (C-13)O line data are conservatively interpreted as an upper limit, the (C-12)O/(C-13)O ratio is not less than 60. Our result supports the p...
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Evidence is found for periodic density structure in the highly fragmented interior of the Orion A molecular cloud from analysis of a large scale map of C(O-18) J = 1 - 0 emission. The spatial wavelength is about 1 parsec, and extends at least over 2 degrees along the main filament of Orion A and is also observed in other filamentary structures in O...
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A study of the structure of the dense core in the dark cloud Barnard 5 (B5) and the circumstellar environment of B5 IRS 1 is presented. CO-18 and CS observations show a dense core of about 50 solar masses with a velocity gradient around the NH3 core in B5. A map of the CO outflow from IRS 1 shows the outflow to extend in a direction nearly perpendi...
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AST/RO (Antarctic Submillimeter Telescope and Remote Observatory), a joint project between AT&T Bell Labs, Boston University and the University of Illinois, will place a 1.7-m submillimetre telescope at the South Pole (a high, dry site) in 1992. The highly automated off-axis parabolic telescope will be equipped initially with two channels of 500 GH...
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Molecular gas in the interior of the Orion superbubble consists of sheets, filaments, and partial shells in which the active star forming dense cloud cores are embedded. The main body of the Orion A and B clouds and at least 14 smaller clouds in Orion region are cometary in appearance suggesting strong interaction with massive stars in the Orion OB...
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In order to study the excitation conditions in the Orion-A region, we applied an LVG code to 12CO, 13CO and C18O data obtained with the AT&T Bell Laboratories 7-meter telescope in USA (CO isotopes: J = 1−0, CS: J = 2−1) and the radiotelescope of the ”Groupe d’Astrophysique de Grenoble“ in France (CO isotopes: J = 2−1).
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At a distance of 65 pc, the molecular cloud MBM 12 is the nearest molecular complex known. Results of extensive molecular and preliminary atomic spectral mapping of the MBM 12 complex are reported. The total H2 mass of the cloud is estimated to be about 30 solar masses. Although there are over 50 distinct emission clumps and the (C-13)O (J = 1-0) m...
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An analysis of the physical conditions in a region of the Orion A molecular cloud is presented. Based on a multitransition study of CO and its isotopes, the analysis uses the large-velocity-gradient method to determine the cloud parameters. It is found that the inclusion of radiative coupling or different collision rate coefficients does not affect...
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The relationships among IR emission, CO isotope intensities, and visual extinction in the molecular cloud Barnard 5 are studied in order to evaluate various candidates as mass tracers or molecular material and to determine the properties of dust grains emitting at 60 and 100 microns. The results establish a strong correlation between the 100 micron...
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A decade of galactic center observations at the Crawford Hill 7 m antenna is summarized. The galactic center region contains several hundred high-mass, high-density molecular clouds with physical properties very different from clouds in the outer galactic disk. There is also a considerable amount of molecular gas not bound into clouds, but sheared...
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Moderate resolution (2,5) observations of the 13CO J=1→0 and J=2→1 lines in the Orion A molecular cloud reveal that 13CO is optically thick over all the main filament. We present a 13CO column density map of this region, as deduced from both lines using an LVG code. This map reveals several peaks in the main filament with column densities greater t...
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IRAS and (C-13)O data are presented for the dark cloud Barnard 5. The 100-micron and (C-13)O emission are well correlated and suggest that the 100-micron emission traces the dust and gas column density through the cloud. The 12-micron emission, on the other hand, is anticorrelated with the overall opacity in the cloud, which is interpreted as limb...
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The integrated (C-12)O and (C-13)O emission ratio is compared for several large regions of the Galactic plane with values for the centers of giant molecular clouds (GMCs) and for the average emission for GMCs. Ratios of 6.7 for the plane, 4.5 for whole GMCs, and 3.0 for GMC centers are obtained. These results show that a significant contribution to...
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Measurements of the effective zenith noise temperature of the 20-foot horn-reflector antenna (Crawford, Hogg, and Hunt 1961) at the Crawford Hill Laboratory, Holmdel, New Jersey, at 4080 Mc/s have yielded a value of about 3.5 K higher than expected. This excess temperature is, within the limits of our observations, isotropic, unpolarized, and free...
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Diffuse molecular clouds make a significant contribution to the CO emissivity of the Galaxy, but have little mass.
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A CS map of the galactic center region is presented consisting of 15,000 spectra covering -1 deg. less than 3. deg. 6 min., -0 deg.4 min. less than b less than 0 deg. 4 min., each having an rms noise of 0.15 K in 1 MHz filters. CS is a high-excitation molecule, meaning that it is excited into emission only when the ambient density is less than n mu...
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The detection of a second high-velocity bipolar flow in the dark cloud B335 located in the diffuse envelope to the east of the core is reported. This flow has the same orientation as the first one. The visual extinction in the region between the redshifted and blueshifted lobes is less than or about 1 mag and is not coincident with a condensation....
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High-velocity molecular outflows associated with three and possibly four of the IRAS sources have been detected in B5. (C-18)O mapping indicates that the cloud contains at least five dense fragments, but only IRS 1 appears to be located at a molecular column density maximum. From the time scales of the outflows, it is concluded that star formation...
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Two rotational transitions of CCD, N = 1-2 at 144 GHz and 2-3 at 216 GHz, were detected in a laboratory glow discharge through deuterated acetylene and helium, after which one, N = 2-1, was detected toward the rich molecular cloud behind the Orion Nebula. The 144 GHz transition is a well-resolved spin doublet split by 55 MHz, the components of whic...
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The authors report the results of an unsuccessful search for the J = 1-0 line of 14CO in the envelope of the evolved carbon star IRC+10216. Comparison with models of the envelope emission shows that in the material leaving the star 14C/13C < 0.1.
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A survey of the 12CO emission between longitudes 4° and 90° of the Galaxy is described. The survey consists of strip maps in latitude at 38 galactic longitudes, spaced at equal intervals of sin l. The maps are sampled at intervals of Δb = 2 arcmin with velocity resolutions of 0.65 and 2.6 km/s. The rms noise level of the observations is mostly bett...
Chapter
We report the results of an unsuccessful search for the J = 1–0 line of 14CO in the envelope of the evolved carbon star IRC+10216. Comparison with models of the envelope emission shows that in the material leaving the star 14C/13C < 0.1.
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A table of over 100 positions for CO line observations which have been found to be free of emission above an antenna noise temperature of 0.5 K is presented. An average upper limit on the column density of CO of 9.9 x 10 to the 16th/sq cm is inferred, corresponding to a visual extinction upper limit of 1.5 mag and an H2 column density upper limit o...
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Carbon monoxide column densities are compared to visual extinctions toward field stars in the rho Oph and Taurus molecular cloud complexes. The relationship of C(0-18) column density to extinction is established, and new determinations for (C-13)O column densities are given for a range of visual extinctions extended to beyond 20 mag. A prescription...
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Maps are presented of the J = 2 - 1 and J = 1 - 0 transitions of (C-12)O, (C-13)O, and C(O-18) in the dark cloud B5. The H density and CO fractional abundances are determined along a N-S strip through the center of the cloud. It is found that the density is fairly uniform over most of the cloud, that the fractional abundances of (C-13)O and C(O-18)...
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Observations of five isotopes of HCO(plus), including the first detection in an astronomical source of the very rare isotope (D-13)/CO(plus), and extensive mappings of three of them, have allowed a careful determination of the DCO(plus)/HCO(plus) abundance ratio throughout regions of the cool molecular clouds TMC 1, TMC 2, L 183 (L 134N), L 1450 (N...
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Observations are presented which indicate that the central region of the dark cloud B5 is rotating in the opposite sense to that of the bulk of this approximately 300-solar-mass region. The direction of elongation of the cloud coincides with its axis of rotation; both are perpendicular to the galactic plane and to the direction of the magnetic fiel...
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Isotopic abundance ratios of carbon and oxygen have been determined for the local interstellar medium by observations of carbon monoxide in three dark clouds. The /sup 12/C//sup 13/C ratio is obtained by measurements of the optically thin species /sup 12/C/sup 18/O and /sup 13/C/sup 18/O. The weighted mean ratio for the source B5, B335, and L1262 i...
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A survey of the relative abundances of the isotopic species, (C-12)(S-32), (C-12)(S-34), and (C-13)(S-32) has been made in 14 dense molecular clouds through observations of the J = 2-1 rotational transitions at 3 mm. The abundance ratio, (C-13)(S-32)/(C-12)(S-34), is found to be 1.9 times greater in the galactic center sources than in the galactic...
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The HCN J equals 1-0 lines have been observed in absorption in front of the continuum source Cas A. The spectrum exhibits several features corresponding to HI clouds in the Orion and Perseus arm. The lines are found to be optically thin. For an Orion arm cloud magnitude, an N(HCN) column density of 4 x 10 to the 11th/sq cm is found.
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Chemical fractionation of the various isotopes of carbon monoxide has been studied in four isolated dark clouds. At positions away from the centers of three of the objects - B5, B335, and L1262 - the abundance of (CO-13) relative to C(O-18) is at least a factor of 4 greater than at the central positions. This detection of carbon isotope fractionati...
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C-13 signals have been detected toward five galaxies. The (C-12)O/(C-13)O intensity ratio is about twice as large as that in our Galaxy. This results from the different conditions of observations for external galaxies, namely, different dilution factors.
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The hyperfine structure of HN(C-13) and new frequencies for both HN(C-13) and HNC are determined from resolved spectra in two dark clouds. A quadrupole coupling constant of 0.28 + or - 0.03 MHz has been derived from the data. The new value differs from an earlier published value. Previous confusion is due to alteration of line shapes for these two...
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The J equals 1-0 rotational line of H(C-13)O(plus) has been detected in the dark clouds L134N and Taurus Molecular Cloud 1 (TMC-1) and found to have, at selected positions, an intensity about twice that of the common isotope. The corresponding HC(O-18)(plus) observations, however, yield a normal H(C-13)O(plus)/HC(O-18)(plus) isotope ratio. It is su...
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A study of the relative abundances of the rare isotopic species H(C-12)(N-15) and H(C-13)(N-14) has been made in six dense molecular clouds through observations of the 3.5-mm rotational transitions. The data indicate that in all sources the HC(N-15)/H(C-13)N integrated line-intensity ratio is smaller than that implied by terrestrial isotopic abunda...
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We have measured the interstellar (/sup 17/O)/(/sup 18/O) isotope abundance ratio in eight giant molecule clouds using the J=1..-->..J=0 transition of carbon monoxide at approx.2.7 mm. The average interstellar ratio derived from these data is 0.24, a value which is significantly higher than the corresponding terrestrial abundance ratio of 0.186. Th...
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We have measured the interstellar (Â¹â·O)/(Â¹â¸O) isotope abundance ratio in eight giant molecule clouds using the J=1..-->..J=0 transition of carbon monoxide at approx.2.7 mm. The average interstellar ratio derived from these data is 0.24, a value which is significantly higher than the corresponding terrestrial abundance ratio of 0.186. There is...
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Results are reported for measurements of the relative isotopic abundances of carbon and sulfur in interstellar carbon monosulfide, which were made by observing the 2-mm rotational-line emission from (C-13)(S-32) and (C-12)(S-34) in five dense interstellar clouds: Sgr B, W51, Orion A, M17, and NGC 2264. For each cloud, the (C-13)(S-32)/(C-12)(S-34)...
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The J=1..-->..J=0 transition of carbon monoxide is used to study the abundance ratios of carbon and oxygen isotopes in dense molecular clouds. Very high-quality spectra were obtained of Â¹Â²CÂ¹â¶O (CO), Â¹Â³CÂ¹â¶C(Â¹Â³CO), and Â¹Â²CÂ¹â¸O(CÂ¹â¸O) in 14 regions distributed throughout the galactic plane. Effects of line saturation are carefully ex...
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The reported observations were made with an 11-m radio telescope. The CO map considered has a peak near the position of the infrared continuum source. There is little correlation between the CO contours and any optical structure. The CO contours show a pronounced north-south orientation. CS was observed as a representative example of a stable molec...
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Measurements of the spatial variation of HC-12N-14 and HC-13N-14 line emission from the molecular cloud associated with the Orion Nebula indicate that HC-12N-14 has a high central opacity. This result seems to contradict a recent suggestion that the observed hyperfine structure of the line indicates a low opacity, which in turn would yield a C-13/C...
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We report the determination of the hyperfine, \rho${}$-doubling and rotational constants of the CN molecule, by observation of its $N=1$\rightarrow${}0$ line emission from an interstellar molecule cloud. The $N=1$\rightarrow${}0$ multiplet has seven allowed transitions, all of which were measured to an accuracy of 0.5 MHz or better. This astronom...
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Cases of line emission were observed from the molecular clouds associated with the Orion Nebula and the rho Ophiuchi complex. The emission is attributed to a certain rotational transition of CO consisting of the isotopes C-12 and O-17. This observation signifies the first detection of O-17 outside the solar system. It is pointed out that the relati...
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Interstellar methanol lines at lambda = 2 mm, produced by the J = 3 yields 2, DELTA K=O transitions, have been observed in Ori A, Sgr A, Sgr B2 and Dr 21(OH). The Ori A source appears to be less than l' in extent, with a methanol excitation temperature of ~90 deg K and a column density of ~4x10/sup 15/ cm/sup -1/. (auth)
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Investigation of carbon monoxide spectra in sources where the C-12O-18 line is observed at an intensity typically about one-sixth that of the C-13O-16 line. This pair of lines affords the opportunity of studying the relative abundance of their constituents, especially the astrophysically important C-12/C-13 ratio. Data are presented on a total of n...
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Hydrogen sulfide has been detected in seven Galactic sources by observation of a single line corresponding to the rotational transition from the 1(sub 10) to the 1(sub 01) levels at 168.7 GHz. The observations show that hydrogen sulfide is only a moderately common interstellar molecule comparable in abundance to H2CO and CS, but somewhat less abund...
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A sensitive search was made for 2.64-mm line emission from a cloud of CN, whose excitation is known from optical measurements, with essentially a null result. This provides strong support for the proposition that the excitation temperature deduced from the optical CN lines is equal to the temperature of the microwave background.
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Millimeter emission lines from interstellar methyl cyanide transitions, noting kinetic temperature and hydrogen density
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Interstellar carbonyl sulfide transition at 109.5 GHz, noting column density
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Radio emission detection of para-formaldehyde and 2 mm formaldehyde distribution in Orion IR nebula
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Interstellar silicon monoxide discovery from 130,246 MHz frequency line emission of galactic radio source Sag B2
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Formaldehyde line emission observed from trapezium H II region of Orion nebula, attributing to 140 GHz rotational transition
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Interstellar formyl radical and carbon 13 formyl ion search in galactic radio sources
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IR object IRC plus 10216 carbon monoxide emission at 2.6 mm, noting spectral line width, thermal emission and mass
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The 000-101 transition of HCO at 86.796 GHz has been sought but not found in the direction of five galactic radio sources showing strong lines of CO or H2CO. A predicted line of HC13O+ at 86.708 GHz was also not detected.