Masaki Morimoto

Detection of intense unidentified lines in TMC-1

A wide-band microwave spectral scan of TMC-1 has been performed for the first time using the Nobeyama 45 m telescope and two 16,000 channel acoustooptical radio spectrometers for the frequency regions of 22-24 GHz and 36-50 GHz. Seven strong lines which could not be identified with any known molecules, including the U45379 reported by Suzuki et al. (1984), were detected. The profiles of the unidentified lines are shown and their observed parameters are summarized. 10 references.

VLBI Monitoring Observations of Water Masers around the Semi-Regular Variable Star R Crateris

AbstractWe monitored water-vapor masers around the semi-regular variable starR Crateris with the Japanese VLBI Network (J-Net) at the 22 GHz band duringfour epochs with intervals of one month. The relative proper motions and Doppler-velocity drifts of twelve maser features were measured. Most ofthem existed for longerthan 80 days. The 3-D kinematics of the features indicates a bipolar expanding flow.The major axis of the asymmetric flow was estimated to be at P.A. = 136 ◦ . Theexistence of a bipolar outflow suggests that a Mira variable star had already formeda bipolar outflow. The water masers are in a region of apparent minimum radii of1.3 × 10 12 m and maximum radii of 2.6 × 10 12 m, between which the expansion ve-locity ranges from 4.3 to 7.4 km s −1 . These values suggest that the water masers areradially accelerated, but still gravitationally bound, in the water-maser region. Themost positive and negative velocity-drifting features were found relatively close to thesystemic velocity of the star. We found that the blue-shifted features are apparentlyaccelerated and the red-shifted apparently decelerated. The acceleration of only theblue-shifted features seems to be consistent with that of the expanding flow from thestar.Key words: masers — stars: late-type — stars: individual (R Crateris)1

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.

Excitation of Interstellar Molecules in the Ori-Kl Source

A molecular spectral line survey of the title source detected 166 molecular lines from 18 interstellar molecules in the frequency ranges of 34.25–50.00, 83.50–84.50, and 86.00–91.50 GHz. For each molecule, gaussian decomposition of the velocity components in the transition profiles gave consistent radial velocity and linewidth. Rotation diagrams were drawn for each velocity component.

A Near Infrared Camera Refrigerated by Two Stirling Machines – an Alternative to Robotic Telescopes

We have developed and tested a new near infrared camera equipped with a 512 × 512 PtSi CCD and cooled by two independent Stirling Cycle refrigerators. The camera, installed on the 60 cm reflector telescope of the Nishi-Harima Astronomical Observatory (NHAO) since April 2000, has begun regular observations toward infrared objects. Since the reasonable cost and lower maintenance needs of the camera make it more attractive, we introduce it as an alternative to robotic telescopes.

Real-time VLBI system using telephone network for online system diagnosis

A real-time VLBI (Very Long Baseline Interferometer) system using conventional telephone lines is proposed. This system enables us to check if the VLBI network is alive by on-line manner, which is useful to reduce the loss of observation time caused by system malfunctions. In this system, a beacon of satellite or the emission from cosmic maser sources is received. The narrow-band spectral profile of the received signal leads us to compress the data up to the size less than the capacity of transmission rate on conventional telephone lines, that is to say a few tens of kbps. Additional devices for the real-time operation are A-D converters, PCs and modems, which are not special ones. As the link between the VLBI stations is performed by the conventional way, the system is applied not only to domestic VLBI networks, but also to international VLBI networks, in which a part of the VLBI stations is located in rural place. It has been confirmed that the cross-correlation is clearly detected for the compressed beacon wave data.

The CRL 34-m radio telescope at Kashima — A new strong tool in maser research — and the first results of a 22 GHz H2O maser survey

The CRL 34-m radio telescope at Kashima was completed in 1988. The telescope is equipped with low noise receivers from 1.4 GHz to 44 GHz and is able to observe most of the important astronomical masers in this frequency range. We made an automatic maser survey software and started an H20 maser survey at November 1991 for IRAS color selected objects. Until the end of January 1992, about 930 sources were observed with the rms noise level of 0.1 Jy and about 300 sources were detected.

Results from Nobeyama Radio Observatory (NRO) — A Progress Report

The title telescope — in operation since 1982 — gives a surface accuracy of better than 0.2 mm (r.m.s.), with an aperture efficiency of about 25% at 115 GHz. A 5-element interferometer is at final adjustment stage. Observations of proto-stellar objects, extragalactic objects, and spectral lines are briefly described.

High sensitivity SiO maser survey for Mira variables

Simultaneous observations of the six transitions of SiO for 106 late-type stars were made. The SiO maser emission was detected in 83 stars. Thev=3 maser emission was detected in eight stars, and the29SiOv=0 emission in six stars. The29SiOv=0 emission is stronger and narrower than that of28SiO, suggesting that the29SiO emission is masing.

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.