Main Reflector - resceu.s.u-tokyo.ac.jpsubmm/mtfuji/Mt.Fuji.pdf · at Mount Fuji. Research Center...

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Transcript of Main Reflector - resceu.s.u-tokyo.ac.jpsubmm/mtfuji/Mt.Fuji.pdf · at Mount Fuji. Research Center...

Page 1: Main Reflector - resceu.s.u-tokyo.ac.jpsubmm/mtfuji/Mt.Fuji.pdf · at Mount Fuji. Research Center for the Early Universe (RESCEU) was founded under the COE program leaded by Professor
Page 2: Main Reflector - resceu.s.u-tokyo.ac.jpsubmm/mtfuji/Mt.Fuji.pdf · at Mount Fuji. Research Center for the Early Universe (RESCEU) was founded under the COE program leaded by Professor

Main Reflector 1.2 m

1m

Mount Fuji Submillimeter-wave Telescope is the first Japanese radio

telescope observing the submillimeter-wave radiation from space.

The main reflector of the telescope has a diameter of 1.2 m with the

surface accuracy of 10μm, and is enclosed in a space frame radome

which is transparent for submillimeter-waves. With this telescope, we

are observing the spectral lines emitted by the neutral carbon atoms

in interstellar clouds. The observing frequencies are 492 GHz and

809 GHz, which correspond to the wavelengths of 0.6 mm and

0.4 mm, respectively. On the basis of their large area mapping

observations, we are exploring how interstellar clouds, birthplaces of

new stars, are formed in the Galaxy. Although this is a very small

telescope, we are leading observations of the neutral carbon atom in

the world. This study is being carried out in collaboration with

researchers in several institutes including National Astronomy

Observatory of Japan and National Space Develop Agency.

RadomeThe antenna is enclosed in a space frame radome with a Gore-Tex membrane in order to protect it from wind and precipitation.

Inside the ReceiverA Nb-based superconductor-insulator-superconductor (SIS) junction fabricated at Nobeyama Radio Observatory is employed as a mixing element in the heterodyne receiver.

Satellite Communication AntennaThe telescope is operated in a remote way from the University of Tokyo using a satellite communication system.

Superconductor Receiver (809 /492 / 350 GHz)A low noise receiver using superconductor technology is equipped on the telescope to detect faint signals from space.

Lower CabinVarious telescope control instruments are accommodated here.

Page 3: Main Reflector - resceu.s.u-tokyo.ac.jpsubmm/mtfuji/Mt.Fuji.pdf · at Mount Fuji. Research Center for the Early Universe (RESCEU) was founded under the COE program leaded by Professor

Submillimeter-wave from space is heavily absorbed by

water vapor contained in the earth atmosphere. Because

of this reason, a high-altitude and dry site is essential for

ground-based submillimeter-wave observations. So far it

has been carried out at Mauna Kea (el. 4200 m) ,

Gornergrat (el. 3150 m), and so on. Mount Fuji is the

highest mountain in Japan, whose elevation is 3776 m

from the sea level. We have a very good observing

condition at Mount Fuji in the winter season because of

low temperature and low humidity.

Tra

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Ele

ctro

mag

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Wav

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om S

pace

(%

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Frequency(GHz)

Nobeyama

Mount Fuji

Frequencies of the Neutral Carbon Atom

492GHz 809GHz

Submillimeter-wave100

50

0300 500 700 900

Water Molecule

Absorbed

Submillimeter-wave from Space

Atmosphere

Space

Submillimeter-wave Telescope

Discovery of A Formation Site of Molecular Clouds

The Taurus molecular cloud is a typical star forming region,

which is closest to the Sun. With Mount Fuji Submillimeter-wave

Telescope, we have first delineated the distribution of the neutral

carbon atom in this cloud. A color map in the right figure shows

the emission of the neutral carbon atom, where the red indicates

the most bright place. On the other hand, the contour map

represents the emission of the carbon monoxide molecule

(C18O) observed with Nobeyama 45 m radio telescope by

Sunada and Kitamura. An anticorrelation between the

distributions of the neutral carbon atom and the carbon

monoxide molecule can be seen. The neutral carbon atom

gradually changes into the carbon monoxide molecule by

chemical reactions. Hence, molecular clouds already formed are

well seen by the carbon monoxide molecule, whereas the

formation site of molecular clouds can be picked up by the

neutral carbon atom. It is most likely that the molecular cloud

formation is forming from north to south in this region.

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Mount Fuji Water Vapor

Page 4: Main Reflector - resceu.s.u-tokyo.ac.jpsubmm/mtfuji/Mt.Fuji.pdf · at Mount Fuji. Research Center for the Early Universe (RESCEU) was founded under the COE program leaded by Professor

Inquiry

Dr. Satoshi Yamamoto, Dr. Tomoharu OkaDepartment of Physics, Graduate School of Science, The University of Tokyo7-3-1 Hongo, Bunkyo-ku 113-0033, JAPANPhone: +81-3-5841-4197E-mail : [email protected]

Reprinting of any text, photo, illustration and any part thereof in this pamphlet without a prior consent of RESCUE are prohibited.

The Brief History

1992

1994

1995

1997

1998

1999

First Complete Survey of Orion Giant Molecular Cloud with Neutral Carbon Atom

The Orion giant molecular cloud is a huge

cloud lying behind the famous Orion nebula

M42, whose total mass is estimated to be

10,000 times the solar mass. With Mount Fuji

Submillimeter-wave Telescope, we have

observed a whole of the cloud with the

spectral line of the neutral carbon atom. The

observed region is larger by a factor of 10

than the previous observations. The left panel

shows the distribution of the neutral carbon

atom, where the red color represent the most

intense position. The right panel shows the

distribution of the carbon monoxide line as a

reference. The neutral carbon atom is

distributed along the backbone of the giant

molecular cloud. From these results, we are

exploring detailed structures and formation

processes of such a huge molecular cloud.

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Installation of the telescope at Mount Fuji (July 1998)

A discussion on a new submillimeter-wave telescope

project was started, and Mount Fuji was recognized as

its potential site.

With an extensive support by Meteorological Agency of

Japan, a small apparatus for continuous evaluation of

the atmospheric opacity was put on the weather station

at Mount Fuji.

Research Center for the Early Universe (RESCEU) was

founded under the COE program leaded by Professor

Katsuhiko Sato. As one of its research projects, the

construction of the Mount Fuji Submillimeter-wave

Telescope was started.

The telescope system was preinstalled at Nobeyama

Radio Observatory for test operations.

The telescope system was finally installed at the top of

Mount Fuji in July. Scientific observations were started

from November.

RESCEU was established as a formal research center

of Graduate School of Science recognized by Ministry

of Education, Science, Sports, and Culture.

From the highest place in Japan, a top of Mount Fuji,

completely covered with snow and ice,

we are looking at birthplaces of new stars

with a small but sensitive submillimeter-wave telescope

controlled remotely from the University of Tokyo.