Mt. Stromlo Observatory, Australia, and it was shown that all of the sample stars
were of the T Tauri type (Kogure et al. 1992). They thus found that the west side
aggregation is a simple T-association, which is older than the present Orion starforming region.
Photographic observations at the Kiso Observatory were finished in 1993 by the
end of production of large Schmidt plates at the Kodak Company. After that, the
observations have been taken over by single or multiple CCD detectors for deeper
sky surveys.
6.3.4 Agematsu IR Observatory and Infrared Astronomy
Infrared radiation lies between optical and radio radiations in a wavelength range of
0.8–1000 μm, which is subdivided into near (0.8–5 μm), mid (5–30 μm), and far
(30–1000 μm) IR radiation. The terrestrial atmosphere is generally opaque to IR
radiation with several windows, observable from ground-based telescopes.
The first IR observations in Japan were made at the OAO in 1968 with the PbS
detector for the lunar surface by the group of Hayakawa Sachio and Okuda Haruyuki
of Nagoya and Kyoto Universities (Hayakawa et al. 1968). Thereafter, they started
polarization observations in the near-IR spectral region. Polarization is robust
against the unstable sky in Japan. With a polarimeter mounted on the 91-cm
reflector, Hashimoto Jun’ichiro, Maihara Toshinori, and others observed a bright
late-type supergiant VY Canis Majoris at H and K bands (1.6 and 2.2 μm) and found
a disk structure around the star (Hashimoto et al. 1970).
In 1973, the Agematsu Infrared Observatory (AIRO) was constructed at an
altitude of 1200 m in the Kiso Mountains equipped with a 100-cm IR telescope
(Fig. 6.7). At the AIRO, observational conditions have been substantially improved
with the reduction of background radiation owing to its site at high altitude. By
adopting a second mirror chopping system, high efficiency of observations was
obtained. Moreover, plenty of observational time became available compared to at
the OAO (Okuda 2018).
With this telescope, novae, comets, and the Galactic Center were observed in the
near-IR spectral regions. Noguchi Kunio and his group made narrow-band spectrophotometric observations of 22 carbon stars and 23 M-type stars between 2.85 and
4.1 μm, and they found that all carbon stars exhibited a broad absorption feature
centered at about 3.05 μm, whereas no trace of absorption was found in the M stars.
They suggested that some polyatomic molecules in the carbon-star atmospheres
were possibly responsible for the absorptions (Noguchi et al. 1977).
Sato Shuji and his group carried out broadband IR photometry for Nova
Vulpeculae 1976 (NQ Vul) for a period covering two hundred days after its
discovery. After a gradual decline in optical light, the IR radiation suddenly
increased by about 3.5 mag at L band (3.2–4.1 μm). By comparing optical and IR
spectra, they traced the process of the dust formation and its growth rate in the nova
envelope (Sato et al. 1978).
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6 Postwar Development of Astrophysics, 1946–2000 (Part I: Instrumentation)
were of the T Tauri type (Kogure et al. 1992). They thus found that the west side
aggregation is a simple T-association, which is older than the present Orion starforming region.
Photographic observations at the Kiso Observatory were finished in 1993 by the
end of production of large Schmidt plates at the Kodak Company. After that, the
observations have been taken over by single or multiple CCD detectors for deeper
sky surveys.
6.3.4 Agematsu IR Observatory and Infrared Astronomy
Infrared radiation lies between optical and radio radiations in a wavelength range of
0.8–1000 μm, which is subdivided into near (0.8–5 μm), mid (5–30 μm), and far
(30–1000 μm) IR radiation. The terrestrial atmosphere is generally opaque to IR
radiation with several windows, observable from ground-based telescopes.
The first IR observations in Japan were made at the OAO in 1968 with the PbS
detector for the lunar surface by the group of Hayakawa Sachio and Okuda Haruyuki
of Nagoya and Kyoto Universities (Hayakawa et al. 1968). Thereafter, they started
polarization observations in the near-IR spectral region. Polarization is robust
against the unstable sky in Japan. With a polarimeter mounted on the 91-cm
reflector, Hashimoto Jun’ichiro, Maihara Toshinori, and others observed a bright
late-type supergiant VY Canis Majoris at H and K bands (1.6 and 2.2 μm) and found
a disk structure around the star (Hashimoto et al. 1970).
In 1973, the Agematsu Infrared Observatory (AIRO) was constructed at an
altitude of 1200 m in the Kiso Mountains equipped with a 100-cm IR telescope
(Fig. 6.7). At the AIRO, observational conditions have been substantially improved
with the reduction of background radiation owing to its site at high altitude. By
adopting a second mirror chopping system, high efficiency of observations was
obtained. Moreover, plenty of observational time became available compared to at
the OAO (Okuda 2018).
With this telescope, novae, comets, and the Galactic Center were observed in the
near-IR spectral regions. Noguchi Kunio and his group made narrow-band spectrophotometric observations of 22 carbon stars and 23 M-type stars between 2.85 and
4.1 μm, and they found that all carbon stars exhibited a broad absorption feature
centered at about 3.05 μm, whereas no trace of absorption was found in the M stars.
They suggested that some polyatomic molecules in the carbon-star atmospheres
were possibly responsible for the absorptions (Noguchi et al. 1977).
Sato Shuji and his group carried out broadband IR photometry for Nova
Vulpeculae 1976 (NQ Vul) for a period covering two hundred days after its
discovery. After a gradual decline in optical light, the IR radiation suddenly
increased by about 3.5 mag at L band (3.2–4.1 μm). By comparing optical and IR
spectra, they traced the process of the dust formation and its growth rate in the nova
envelope (Sato et al. 1978).
146
6 Postwar Development of Astrophysics, 1946–2000 (Part I: Instrumentation)