Main Reflector - resceu.s.u-tokyo.ac.jpsubmm/mtfuji/Mt.Fuji.pdf · at Mount Fuji. Research Center...
Transcript of Main Reflector - resceu.s.u-tokyo.ac.jpsubmm/mtfuji/Mt.Fuji.pdf · at Mount Fuji. Research Center...
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.
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
nspa
renc
y of
Ele
ctro
mag
netic
Wav
es fr
om S
pace
(%
)
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
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.