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Thaddeus, P.

Publications and source records attributed to Thaddeus, P..

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Tentative identification of U93.174 as the molecular ion N2H/+/

On the basis of a consideration of the rotation constant and the hyperfine structure together with the results of an ab initio structural calculation it is suggested that the three closely space new interstellar lines near 93.174 GHz reported by Turner (1974) might have been produced by the molecular ion N2H(+). It is pointed out that the identification of N2H(+) is reasonable also in terms of current ideas of interstellar chemistry.

Green, S.↗
NASA NTRS1974

Detection of the J = 1 to 0 rotational transition of vibrationally excited silicon monoxide

The v = 1,J = 1 to 0 rotational transition of SiO at 43.1 GHz has been detected in the direction of Becklin's star in the Orion Nebula, and in the M-type star W Hya. In Orion two velocity components are observed, one (the stronger) at a radial velocity of 17 km/sec, the other at -7 km/sec; in W Hya a single line is observed at 39 km/sec. In each case a line at the same radial velocity has been observed at 86.2 GHz in the v = 1,J = 2 to 1 transition, so that the presence of vibrationally excited SiO would seem to be confirmed beyond a reasonable doubt. In the v = 1 state, the photon fluxes of the J = 2 to 1 and 1 to 0 transitions are about equal, suggesting saturated masers occupying the same region of space.

Thaddeus, P.↗
NASA NTRS1974

Rotational excitation of HCN by collisions

Rate constants for the rotational excitation of HCN by collisions with He atoms at temperatures below 100 K were computed from first principles and are presented in tabular form. The potential energy surface was obtained by using the uniform electron gas model of Gordon and Kim (1972) and then joined smoothly to the asymptotic long-range perturbation theory potential valid at large separations. Quantum close-coupling theory was used to analyze the collision dynamics. Individual rates are believed to be accurate to within 50% above 30 K and within a factor of two below 20 K. The results should be extendable to excitation by collision with H2 and may therefore be of value in the study of interstellar clouds.

Green, S.↗
NASA NTRS1973

A large carbon monoxide cloud in Orion

Carbon monoxide line emission was observed at a wavelength of 2.6 mm in an area of L1630, a diffuse dark nebula forming a bridge between NGC 2024 and the reflection nebula NGC 2068. The absence of a 21-cm counterpart to this region of high visual extinction suggests that L1630 is predominantly molecular hydrogen. The molecular hydrogen mass, estimated from the carbon monoxide observations, is found to comprise a significant fraction of the total mass of stars and gas within the boundaries of I Ori association.

Tucker, K. D.↗
NASA NTRS1973

Oscillator strengths for the X/1 Sigma+/ - A/1 Pi/ system of CH+.

Oscillator strengths for the X/1 Sigma+/ - A/1 Pi/ system of CH+ computed to an estimated accuracy of 10 percent from ab initio wave functions are presented. These oscillator strength values are given for the two strongest interstellar lines of 4232 and 3957 A.

Yoshimine, M.↗
NASA NTRS1973

Hyperfine structure of furan.

The hfs of five rotational transitions of furan (C4H4O) has been resolved with a beam maser spectrometer with a resolution of about 500 Hz. All significant details of the observed structure are accounted for by the spin-spin and spin-rotation interactions of the four protons, and the coupling constants for these interactions have been determined to high precision. In particular, the diagonal elements of the spin-rotation tensors have been determined to about 10 Hz.

Tomasevich, G. R.↗
NASA NTRS1972

Interstellar hydrogen sulfide.

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 abundant than HCN and much less abundant than CO.

Thaddeus, P.↗
NASA NTRS1972

Laboratory measurement of the 2-centimeter, 2/11/-2/12/ transition of normal formaldehyde and its carbon-13 and oxygen-18 species.

Beam-maser spectrometric measurements to an accuracy of about 100 Hz have been conducted of the 2(11)-2(12) transition for the isotopic species of greatest astronomical interest - i.e., H2CO, H2(13)CO, and H2C(18)O. The samples used were not isotopically enriched, monomeric formaldehyde vapors. For these species, all the coupling constants required to calculate the hyperfine structure of any rotational transition have been determined.

Tucker, K. D.↗
NASA NTRS1972

Interstellar formaldehyde. I - The collisional pumping mechanism for anomalous 6-centimeter absorption.

Investigation of the quantum mechanics of the collisional pumping process which Townes and Cheung (1969) propose as the cause of 'anomalous' formaldehyde absorption in diffuse dark nebulae discussed by Palmer et al. (1969). Quantum effects are taken into account in an attempt to determine whether such nebulae are likely to provide the physical conditions required for the collisional pumping process.

Thaddeus, P.↗
NASA NTRS1972

Survey of molecular lines near the galactic center. I - 6-centimeter formaldehyde absorption in Sagittarius A, Sagittarius B2, and the galactic plane from 359.4 to 2.2 deg galactic longitude.

The data obtained indicate that the formaldehyde is concentrated in distinct clouds to a much greater extent than atomic hydrogen. The findings suggest that most of the mass in these clouds is in the form of molecular hydrogen. The locations of four dominant clouds are reported. The strongest formaldehyde features are apparently associated with the galactic nucleus. Estimates of the hydrogen density in the clouds, based on the assumption of stability and also on a comparison with local dark clouds, indicate a number density in the range from 1000 to 10,000 per cc, and a mass of approximately 500,000 solar masses.

Scoville, N. Z.↗
NASA NTRS1972

Search for interstellar furan and imidazole.

Results are reported on an unsuccessful 6-cm search for the heterocyclic carbon ring molecules furan and imidazole. Upper limits in brightness temperature of 0.25 K or less are found for furan in 11 galactic sources, and of less than 0.1 K for imidazole in Sgr A and Sgr B2.

Dezafra, R. L.↗
NASA NTRS1971

Lower limit to the interstellar C 12/C 13 ratio in the direction of 20 Tauri.

Results of photoelectric scanning of the spectrum of 20 Tau in the vicinity of 4232 A of interstellar CH(+). From the observed absence of the isotopically shifted line of super 13CH(+) it is deduced that the C 12/C 13 isotopic abundance ratio in this direction is greater than 33, and hence consistent with the terrestrial value.

Vanden Bout, P.↗