Unveiling the formation of stars and planets with a large infrared-optical telescope

Diffraction-limited imaging in the near-IR (with the aid of adaptive optics) to middle-IR wavelengths will be a major breakthrough with 8m IR-optical telescopes. Special interest is on the scale of planet formation, that is, within 100 AU of the embedded sources in the nearby Taurus or Ophiuchus clouds. In this report, we demonstrate the sensitivity of a telescope with a virtual instrument that covers a wide spectral range.     

Cep A: A possible proto-cluster

We present high resolution CS and CO maps of Cep A region made with the 45m 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 gravitationally unstable and appears to be in a contracting phase to form a cluster of massive stars.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.NRO, a branch of the Tokyo Astronomical Observatory, University of Tokyo, is a cosmic radio observing facility open for outside users.     

Tomographic imaging of hydrated crust and mantle in the subducting Pacific slab beneath Hokkaido, Japan: Evidence for dehydration embrittlement as a cause of intraslab earthquakes

We estimate detailed three-dimensional seismic velocity structures in the subducting Pacific slab beneath Hokkaido, Japan, using a large number of arrival-time data from 6902 local earthquakes. A remarkable low-velocity layer with a thickness of ~ 10 km is imaged at the uppermost part of the slab and is interpreted as hydrated oceanic crust. The layer gradually disappears at depths of 70–80 km, suggesting the breakdown of hydrous minerals there. We find prominent low-velocity anomalies along the lower plane of the double seismic zone and above the aftershock area of the 1993 Kushiro-oki earthquake (M7.8). Since seismic velocities of unmetamorphosed peridotite are much higher than the observations, hydrous minerals are expected to exist in the lower plane as well as the hypocentral area of the 1993 earthquake. On the other hand, regions between the upper and lower planes, where seismic activity is not so high compared to the both planes, show relatively high velocities comparable to those of unmetamorphosed peridotite. Our observations suggest that intermediate-depth earthquakes occur mainly in regions with hydrous minerals, which support dehydration embrittlement hypothesis as a cause of earthquake in the subducting slab.     

High-resolution observations of the Orion bright bar

High resolution strip maps of CS (J=1–0) and H51 line emission across the Orion bright bar are presented. They reveal the existence of a high density molecular layer (molecular sheet) plane parallel to the ionization front. This molecular sheet is redshifted relative to the ambient molecular cloud by about 2 km s^–1. The rapid decrease of the CS emission at about 50 arc sec from the bar suggests that a shock front exists here and the sheet is a post shock layer.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.This work was carried out under the common use observation program at the Nobeyama Radio Observatory (NRO). NRO, a branch of the Tokyo Astronomical Observatory, University of Tokyo, Japan, is a cosmic radio observing facility open to outside users.     

Cooperation aspects of international observatories

From the user's point of view, it is essential to promote collaborations to make full use of large telescopes, by covering the wide range of the wavelengths. To do that efficiently, it is necessary to work with other facilities, often abroad. Other talks in this symposium are concerned about the spatial resolution or the coverage at one wavelength or one to two octaves in wavelength. Though the above is important, that is not enough to attach the mysteries in the Universe, since a considerable amount of energy is emitted in the infrared, and mass exists in molecular gas form. In this paper, two examples of international, multiwavelength work are shown which turned out to be beneficial for the world-wide community. One is the Japan-U.K. arrangement mainly between the radio and infrared facilities, and the other is the arrangement around James Clerk Maxwell Telescope (JCMT), challenging a new regime of the observational astronomy.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.