Norio Kaifu

Observations of some oxygen-containing and sulfur-containing organic molecules in cold dark clouds.

Observations of nine oxygen- and sulfur-containing organic molecules have been made toward the cold dark clouds TMC-1 and L134N. We have confirmed the presence of para-ketene (H2C2O) in TMC-1, have for the first time observed ortho-ketene, and find a total ketene column density approximately 1 x 10(13) cm-2. Thioformaldehyde (H2CS) is easily detectable in both TMC-1 and L134N, with a column density about 5 times larger in the former source (approximately 3 x 10(13) cm-2). The fractional abundance of ketene is comparable to the predictions of ion-molecule chemistry, while that of thioformaldehyde in TMC-1 is one to two orders of magnitude greater than that expected from such models at steady state. Interstellar sulfur chemistry thus continues to be poorly understood. We set upper limits for the column densities of formic acid (HCOOH), vinyl alcohol (CH2CHOH), methyl formate (HCO2CH3), formamide (NH2CHO), methyl mercaptan (CH3SH), isothiocyanic acid (HNCS), and thioketene (H2C2S) in both sources.

Laboratory microwave spectroscopy of the linear C3H and C3D radicals and related astronomical observation

Laboratory observations of rotational spectral lines of the C{sub 3}H and C3D radicals in their ground and vibrationally excited states are compared with astronomical observations with the Nobeyama Radio Observatorys 45-m radio telescope carried out toward IRC + 10216 in May 1988. The C{sub 3}H radical is found to have an extremely low vibrationally excited state, nu4(2Sigma mu), caused by the Renner-Teller effect in the nu4 (CCH bending) state. The radio telescope observations failed to detect the lines of the vibrationally excited C3H at the rms noise level of 24 mK. The upper limit to the column density of the nu4(2Sigma mu) is estimated to be 3 x 10 to the 12th/sq cm. 27 refs.

A new interstellar polyatomic molecule: detection of propynal in the cold cloud TMC-1.

We report the detection of the acetylene derivative propynal (HC triple bond CCHO) in the cold cloud TMC-1, with an abundance that is very close to that for the related species tricarbon monoxide (C3O). Propadienone, an isomer of propynal with the formula H2C=C=C=O, was not detected and is hence less abundant than either C3O or HC2CHO.

TRICARBON MONOXIDE IN TMC-1

We report the measurement of three new lines of C3O in TMC-1. The observed peak antenna temperatures, appropriately corrected for atmospheric and telescope losses, are found to be consistent with a large velocity gradient radiative transfer model whose parameters span the range of standard values for this cloud. The derived fractional abundance for C3O is 1.4 x 10(-10), comparable with the results predicted from a model calculation based on a gas-phase ion-molecule reaction scheme. The results of negative searches for C3O in six other sources are not inconsistent with expected conditions in these clouds.

Laboratory detection of a new interstellar free radical CH2CN(2B1).

An asymmetric-top free radical CH2CN, which as a 2B1 ground state, was detected for the first time by laboratory microwave spectroscopy. The radical was produced in a free-space absorption cell by a DC glow discharge in pure CH3CN gas. About 60 fine-structure components were observed for the N = 11-10 to 14-13 a-type rotational transitions in the frequency region of 220-260 GHz, and many hyperfine resolved components for the N = 4-3 and 5-4 transitions in the 80 and 100 GHz regions, respectively. The molecular constants, including the rotational constants, centrifugal distortion constants, and spin-rotation coupling constants with centrifugal distortion correction terms were determined from the fine-structure resolved transitions, and the hyperfine coupling constants due to the hydrogen and nitrogen nuclei were obtained from the low-N transitions. As a result we assigned U100602 and U80484 from Sgr B2, and U40240 and U20120 from TMC-1, to the N = 5-4, 4-3, 2-1, and 1-0 transitions with K-1 = 0 of the CH2CN radical.

Molecular envelope of the planetary nebula NGC 7027

Strong emission of HCO(+) J = 1-0 has been detected in the molecular envelope of planetary nebula NGC 7027. A modeling of the envelope including a balance of thermal heating and cooling of the gas leads to a mass-loss rate of 0.0003 solar mass/yr, and the abundances of CO, HCO(+), and HCN of 0.0001, 3 x 10 to the -8th, and 0.9 x 10 to the -8th per H2, respectively. It is suggested that the large observed abundance of HCO(+) can be explained either by the ionization due to soft X-rays from the central star or a high gas-dust heat exchange rate. 44 refs.

RADIOASTRONOMICAL OBSERVATIONS OF COMETS IRAS-ARAKI-ALCOCK (1983D) AND SUGANO-SAIGUSA-FUJIKAWA (1983E)

Abstract Detections and upper limits to the continuum emission (1 ≤ λ ≤6 cm) and spectral line emission (OH, CO, CS, HCN, HCO + , CN, CH 3 CN, CH 3 C 2 H, NH 3 , H 2 O, HC 3 N, CH 3 CH 2 CN) are reported from radio observations of Comets 1983d and 1983e. Comparison is made with observations of CN at optical wavelengths. These results may be useful in planning future cometary observations.

A sensitive line search in circumstellar envelopes

Recherche des raies moleculaires dans le domaine 85-89 GHz pour un echantillon de 11 etoiles a enveloppe. Ont ete observees des emissions de 29 SiO, 28 SiO, HCN, H 13 CN, HC 5 N, HCO + , C 2 H, C 4 H et C 3 N. Dans plusieurs etoiles, a ete detectee la transition maser 29 SiO J=2-1. En outre une emission HCN a ete observee dans letoile riche en oxygene, VY CMa dont le profil presente une legere asymetrie par rapport au centre de la raie qui est interpretee en termes dune activite de lenveloppe circumstellaire