N. Kaifu

Detection of five C-13 isotopic species of HC5N in TMC-1

Les raies rotationnelles J = 14-13 des 5 especes isotopiques 13 C du cyanodiacetylene HC 5 N ont ete detectees dans le nuage moleculaire TMC-1. Les rapports isotopiques du carbone sont calcules a partir des abondances des especes normales et isotopiques de HC 5 N, et les rapports sont trouves proches de ceux du voisinage solaire. Le degre de fractionnement chimique de lisotope du carbone pour les 5 especes isotopiques de HC 5 N est etudie.

Search for HC3NH+ : the upper limit of the column density in TMC-1

Les observations radio, en direction de TMC-1, de detection de cyanoacetylene (HC 3 NH + ) sont presentees. Les limites superieures de la densite de colonne du cyanoacetylene et des rapports dabondance [HCNH + ]/[HCN] et [HC 3 NH + ]/[HC 3 N] sont etablis.

A Search for Millimeter Wave Spectral Lines from Comet Sugano-Saigusa-Fujikawa (1983e)

Abstract The search for radio spectral lines from Comet Sugano-Saigusa-Fujikawa (1983e) was conducted using the 45-m telescope of Nobeyama Radio Observatory. The frequency ranges of 44.0–46.0 and 47.5–49.5 GHz were surveyed down to ΔT A ∗ ( rms ) = 20–30 mK , with a beam size of ∼35 arc sec. Upper limits have been established for spectral lines of atomic hydrogen, CS, OCS, SO2, H2CO, CH3OH, HCCCCCN, HCOOCH3, CH3OCH3, and CH3CH2CN. The J = 5−4 line from HCCCN in the vibrational ground state possibly has been detected but not confirmed. The suggested total amount of HCCCN in the coma is consistent with the possible picture that HCCCN is the main parent molecule of CN.

HCO/sup +/emission in the galactic center region. I. observations

HCO/sup +/ emission (3.4 mm, J=1--0) in the galactic center region has been observed toward the dense molecular clouds near Sgr A and Sgr B2 at over 20 points. The profiles are asymmetric, and are very widely extended in velocity like the /sup 12/CO line in spite of the high excitation requirements of the HCO/sup +/ line. A position-velocity map along the galacitc plane including the galactic nucleus was obtained. Comparison with the HCN emission leads us to the conclusion that the number density ratio (HCO/sup +/)/(HCN) is higher by an order of magnitude in the diffuse region. This behavior is discussed in terms of the ion-molecule reaction scheme. A dip of 0 km s/sup -1/, which is probably due to self-absorption by foreground cold molecular gas, was found in the HCO/sup +/ profiles as well as in spectra of HCN. The abundance of HCO/sup +/ relative to H/sub 2/ in the cold cloud is estimated to be > or approx. =10/sup -9.5/, which is remarkable large for such a low density cloud.

Cep A: A possible proto-cluster

We present high resolution CS and CO maps of Cep A region made with the 45 m telescope at Nobeyama. The CS map shows that a dense cloud surrounding the proto-star cluster extends in the North-South direction and is probably rotating. The bipolar molecular flow apparent in the CO maps is well-collimated along East-West direction within 0.2 pc from the proto-stars. The dense cloud is gravita-tionally unstable and appears to be in a contracting phase to form a cluster of massive stars.

Fine Structure of Molecular Clouds within 1 Minute of Arc of the Galactic Center

We have observed the HCN(J=1-0) line in the vicinity of the galactic center with the 18″ beam of the Nobeyama 45-m telescope. Profiles were taken at 53 points within 1 arcmin from the galactic nucleus [R.A. = 17h42m29.29s, Dec. = −28°59′17.6″ (1950)] with a 10″ grid (see figure 1). A SSB cooled-mixer receiver (TRX = 600 K) and a wideband AOS (acousto-optical radiospectrometer) with 250 kHz resolution were used.

The Brightness Distribution of Ori A at 4.1 mm in the 101-000 Line of Para-Formaldehyde and in the Continuum

The 4.1-mm continuum emission shows a peak at the Trapezium stars and an extension to the west, where the molecular and IR sources are. The 4-mm line of para-formaldehyde has a similar distribution to that of the 3-mm line of HCN and extends more to the north than the 2-mm line of ortho-formaldehyde. This probably means a lower temperature in the northern part of the cloud.