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An infrared complex has been found in the radio arc region near the Galactic center. The complex consists of three sources that are close (< 10″) to each other, and are almost identical in every point of their characteristics; having the same energy spectrum and the same polarization. The observed polarizations are large; 5% at the K-band, and are parallel to the galactic plane. Both behaviors are compatible to those of the galactic center sources, suggesting that the sources are located near the galactic center. The energy spectra are very similar to each other, with large infrared excesses, peaking near the M-band. The luminosity of each source is estimated to be as high as 3-5x105 L⊙, after correcting for interstellar extinction assuming that they are located near the Galactic center; their luminosity is comparable to those of supergiant stars. By CVF spectrophotometry no CO-band absorption nor Brγ emission has been detected, thus no evidence for either M-supergiant nor OB supergiant has been obtained. On the other hand, the very close linear distances, 0.5 pc among each other, suggests their physical relationship, i.e., they should be very young objects, otherwise they would have been dispersed far apart.
The inner region of the Galaxy has been explored by means of near-infrared observations; the distribution and population of the stars are studied from the near-infrared brightness mapping and star counts in the Milky Way, while the magnetic-field configuration is probed by the near-infrared polarimetry.
An extensive survey of [CII] line emission has been made with a balloon-borne infrared telescope. It has been found that the emission is diffuse and ubiquitously distributed in general interstellar space.
A cluster of luminous infrared sources has been found near the Galactic Center. It consists of five identical stars clustered in a compact volume, to be called an IR quintuplet. They are all highly reddened, strongly polarized and associated with deep absorptions of silicate band and CO vibration band. They seem to be a cluster of young stars newly born near the Galactic Center.
Spectroscopic observations of CII line emission at 157.7 μm have been made of the Galactic Center region with a Fabry-Perot spectrometer onboard a balloon telescope. Strong emission has been detected ubiquitously in a wide area extending between ± 0.7° in galactic longitude. A ring-like structure is suggested from the double lobed distribution of the emission around the Galactic Center.
An extensive survey of [C II] line emission at 158 microns using the balloon borne telescope (BICE) has provided a complete map of the emission intensity distribution in the first and the fourth quadrants of the galactic plane (280° < l < 80°, −5° < b < 5°: Okuda et al. 1993). The emission is very extended throughout the galactic plane in which three intensity maxima are seen towards the tangential directions of the Scutum and the Norma arms as well as in the Galactic center region. However the Galactic center maximum is much less prominent compared with the two other distributions, unlike the case of far infrared continuum and CO emissions.
Diffuse background radiation is integrated light which is consisted of various components of interplanetary, stellar, interstellar, galactic and intergalactic origins as well as cosmic background radiation, the remnant of the pre-galactic phenomena in the early history of the universe.
There are two star clusters near the Galactic Center which might be similar to the central parsec cluster. One is the Quintuplet cluster at (l = 0.16°, b = −0.06°), and the other is the Object #17 cluster at (l = 0.12°, b = 0.02°). The Quintuplet, first found in a polarimetric survey by Kobayashi et al. (1983), includes five very bright stars whose color temperatures are in the range of 600-900K (Okuda et al. 1990; Nagata et al. 1990). Object #17 is a cluster of emission line stars (Nagata et al. 1993, 1995; Cotera et al. 1996; Morris & Serabyn 1996). Spectral features of these two objects observed with the ISOCAM (Kessler et al. 1996; Cesarsky et al. 1996) have been reported (Nagata et al., 1996); absorption features due to O-H (2.8μm) CO2(4.3μm), and CO (4.7μm) are present. In this paper, we report diffuse emission components detected in these two fields.
We present the characteristics of far-infrared (FIR) brightness fluctuations at 90 μm and 170 μm in the Lockman Hole, which were surveyed with the ISOPHOT instrument aboard the Infrared Space Observatory (ISO), and give constraints on the galaxy number counts down to 30 mJy at 90 μm and 50 mJy at 170 μm. The fluctuation power spectra of the FIR images are not dominated by IR cirrus, and are instead most likely due to star-forming galaxies. This analysis indicates the existence of strong evolution in the counts. Especially at 90 μm, the source density is much larger than that expected from the currently available galaxy count models. The galaxies responsible for the fluctuations also significantly contribute to the cosmic infrared background radiation recently derived from an analysis of the COBE data.
The idea for a Working Group (WG) on “Future Large Scale Facilities in Astronomy” grew from the Joint Discussion on this topic held on 20 August 1994, during the IAU General Assembly in The Hague. The IAU Executive Committee approved its formation in August, 1995, and Harvey Butcher was chair until the XXIIIrd General Assembly in Kyoto in 1997.
The reporting period has shown that Space has become a firmly established domain in observational Astrophysics, also in the low energy astrophysics area. The launching of new spacecraft is always an important addition to the capabilities of the Astronomers, but the availability of space observatories is strongly affected by the fact that they disappear as their subsystems become damaged or, for other reasons, become inoperable. The relatively short life of astronomical space facilities has generated new dynamic in the life cycle of observational tools for the astronomer, rather different from that for ground facilities. Launch failures or the final in-orbit functionality verification can also very strongly affect the availability of observational capabilities in space astrophysics. The only spacecraft designed without this built-in life time restriction, is the Hubble Space Telescope, which can be serviced by the Space Shuttle.
For a long time, the inner region of our Galaxy has been veiled by strong interstellar extinction in visible light. The situation has been greatly improved by recent exploration in the infrared region, where the interstellar extinction becomes practically negligible.
Studies of the stellar distribution in the inner region of our Galaxy have been seriously hampered at optical wavelengths by strong interstellar extinction. The extinction decreases considerably at infrared wavelengths, allowing us to look deep into the Galaxy. Motivated by this, we have tried to observe the near infrared brightness distribution of the central region of the Galaxy (Okuda et al., 1977, Maihara et al., 1978, Oda et al., 1978). Similar observations have been carried out by Hayakawa et al., (1976), Ito et al., (1977), and Hofmann et al., (1977). These observations have provided valuable information on the distributions of stars and dust in the inner Galaxy (Hayakawa et al., 1977, Maihara et al., 1978, Oda et al., 1978).
Observations of infrared polarization have been tried in the galactic center. A preliminary result is that the polarization at K-band (2.2 μ) is less than 5 %, much less than that expected from interstellar polarization.
We carried out large–scale (4 × 2 degree) CO multi–line observations toward the central molecular zone (CMZ) in the Galactic center (GC) with the NANTEN2 4m telescope and mapped several diffuse molecular features located at relatively high Galactic latitudes above 0°.6. These high–latitude features are composed of diffuse molecular halo gas and molecular filaments according to their morphological aspects. Their high velocities and high intensity ratios between 12CO J = (2−1) and J = (1−0) clearly indicate their location in the GC, and their total mass amount to ∼10% of that of the CMZ. We discuss that magnetic field is a possible mechanism of these high–latitude molecular features lifting up toward high galactic latitude.
Structure change during the reversion process in an Al−12at.%Li alloy above the metastable δ′ solvus was investigated using a time-resolved small-angle x-ray scattering technique with synchrotron radiation. Results showed that the reversion process started after a short incubation time and that the growth of the stable δ phase began before completion of the δ′ dissolution. The radius of gyration of the second phase particles showed little change in the initial stage of reversion, then increased with time, suggesting the presence of diffuse interfaces between the dissolving δ′ particles and the matrix. It is suggested that the undissolved δ′ particles serve as the nuclei of the more stable δ precipitates, which continue to grow with their radii of gyration showing a parabolic power law in the early stage of growth followed by the familiar coarsening kinetics.
SrRuO3 and CaRuO3 thin films were successfully prepared by metalorganic chemical vapor deposition (MOCVD). Sr(C11H19O2)2(C8H23N5)x – Ru(C11H19O2)3–O2 and Sr(C11H19O2)2(C8H23N5)x. – Ru[(C5H4)(C2H5)]2 - O2 systems, and Ca(C11H19O2)2(C8H23N5)x, – Ru(C11H19O2)3–O2 and Ca(C11 H19O2)2(C8H23N5)x – Ru[(C5H4)(C2H5)]2– O2 systems were used as source materials for SrRuO3 and CaRuO3 thin film preparation, respectively. Sr and Ca source vapors were successfully obtained by bubbling N2 gas including C8H23N5 vapor through liquid sources. Self-composition limiting to keep single phase of SrRuO3 and CaRuO3 was observed under an excess input of the Ru source at 700 – 750 °C for both Ru sources. Epitaxlly grown films with high crystal perfection were grown on various kinds of substrates in this temperature range. Epitaxially grown SrRuO3 film with three kinds of orientation, (100), (110) and (111), were deposited on (100), (110) and (111)SrTiO3 substrates, respectively. By using these films as bottom electrodes, we measured the ferroelectric anisotropy of SrBi2Ta2O9 by preparing (001)- and (116)- oriented films.