中川 貴雄

Experimental studies are carried out to clarify the structures and erosive properties of rectangular cavitating jets. The jet is supplied from a high pressure pump and injected through a rectangular nozzle of aspect ratio of two or four. It discharges into a test cell at specified constant pressure and impinges against a test specimen of aluminum alloy. The structures of the jets are observed by instantaneous photographs and high-speed movies. The erosion tests are conducted at the injection pressure of 18 MPa and the cavitation number of 0.01, 0.02, and 0.03. It is shown that the structures of the cavitating jets issuing from the rectangular nozzles are completely different from those of circular cavitating jets. Corresponding to the jet structures, the erosive properties of the rectangular cavitating jets are different from those of the circular cavitating jets.

資料番号: SA4583057000

ASTRO-F is the second Japanese space mission for infrared astronomy and is scheduled to be launched into a sun-synchronous polar orbit by the Japanese M-V rocket in February 2004. ASTRO-F has a cooled 67 cm telescope with two focal plane instruments: one is the Far-Infrared Surveyor (FIS) and the other is the Infrared Camera (IRC). The main purpose of FIS is to perform the all-sky survey with 4 photometric bands in the wavelength range of 50 - 200 μm. The advantages of the FIS survey over the IRAS survey are (1) higher spatial resolution (30″ at 50-110 μm and 50″ at 110-200 μm) and (2) better sensitivity by one to two orders of magnitude. The FIS survey will provide the next generation far-infrared survey catalogs, which will be ideal inputs for observations by FIRST. The other instrument, IRC, will make deep imaging and low-resolution spectroscopic observations in the spectral range of 1.8 - 26μm. The IRC will make large-area surveys with its wide field of view (10′ × 10′), and will be complementary with the FIRST observations at longer wavelengths.

The Far-Infrared Surveyor (FIS) is one of the on-board instruments on the ASTRO-Fsatellite, which will be launched in early 2004. The first a half year of its mission period of 500days is dedicated to an all sky survey in four bands between 50 and 200μm. On the basis of thepresent hardware specfications and configurations of the FIS, we have written a computer programto simulate the FIS. The program can be used to evaluate the performance of the instrument aswell as to produce input for the data reduction system. In this paper, we describe the currentstatus of the program. As an example of the usage of the simulation program, we present theexpected observing data for three different detector sampling rates. The functions which shouldbe implemented into the program, in the future, are enumerated.

資料番号: SA4592186000

The wide-band energy spectrum of NGC 6240 over the range 0.5-200 keV is investigated using the RXTE and ASCA data. The RXTE data provide the spectrum beyond the ASCA range (0.5-10 keV) with significant detection of signals up to 20 keV and upper limits above 20 keV. The spectrum above 10 keV is found to be very flat. A strong iron K emission line discovered in the previous ASCA observation is also confirmed with the RXTE Proportional Counter Array (PCA). These results provide further evidence for the dominance of a reflection component, i.e. emission from cool material illuminated by an active galactic nucleus (AGN). By fitting the spectra obtained with RXTE and ASCA simultaneously, we satisfactorily modelled the AGN spectrum with a Compton reflection component and probably a transmitted AGN component penetrating through a thick absorber. The X-ray luminosity of the AGN is estimated to be in the range 4 × 10 to 6 × 10 erg s in the range 2-10 keV. which categorizes NGC 6240 among the most luminous Seyfert nuclei. The ratio of the 2-10 keV X-ray luminosity to the infrared luminosity, L (2-10 keV)/L , is 0.01-0.1, which implies a quite substantial, if not dominant, contribution of AGN to the infrared luminosity. 43 44 -1 x IR

Institute of Space and Astronautical Science, Japan New photon-dominated region (PDR) models were constructed for investigation of the [C II] 158 μm fine-structure line emission, particularly of the Galactic [C II] emission observed with the Balloon-borne Infrared Carbon Explorer (BICE). The new models have two noteworthy features: (1) a spherical model cloud is immersed in isotropic stellar radiation, and (2) the incident stellar radiation has a wavelength range from the ultraviolet (UV) to the near-infrared. These features are in contrast to those of previous plane-parallel models in which the incident stellar radiation has been restricted to the UV. This makes the new model more suitable for general Galactic PDRs. Equations for chemical equilibrium and thermal balance are solved simultaneously with radiative transfer in the model cloud. Then the luminosities of the cloud are derived for the [C II] line, the CO (J = 1-0) line, and the continuum at a wavelength of λ = 100 μm. In order to explain the intensity ratios of [C II]/CO (I /I = 1.3 x 10 ) and [C II]/100 μm [I /λI (100 μm) = 5 x 10 ] observed toward the inner Galactic plane, the new models require a moderate (only several times as large as the solar neighborhood value) UV flux of the incident radiation. This flux is an order of magnitude smaller than those required by the previous models. Since the previous models required large incident UV fluxes, PDRs were sometimes considered not to be the primary origin of the diffuse [C II] emission in the Galactic plane. However, the new models show that the observed [C II] emission can originate in molecular clouds immersed in the general Galactic radiation field. This indicates that general Galactic PDRs are a promising candidate for the primary origin of the Galactic [C II] emission. 12 3 -3 [C II] co [C II] λ

Ge:Ga 外囚性半導体を用いた光伝導型検出器は、波長110μmまで感度を持つ遠赤外検出器であり、天文観測や、遠赤外分光など高感度が必要な分野に用いるため研究開発が行われてきた。現在衛星搭載用観測装置のフォーカル・プレーン検出器として各国で研究が進められており、我が国においても次期赤外天文衛星(IRIS)の遠赤外サーベイヤー装置の焦点部にGe:Ga遠赤外検出器が搭載される予定である。検出器の多素子化は同空間分解で同時観測可能領域の拡大をもたらし、観測の効率化及び精度の向上に寄与する。我々は検出器の二次元化を目指し、アレイ化に適した構造である透明電極を用いたLongitudinal型Ge:Ga検出器を開発し、それを極低温動作読み出し回路にインジウムを用いて直接コンタクトをとるダイレクトハイブリッド構造の開発を行った。

We made a series of ASCA observations of Ultra Luminous Infrared Galaxies (ULIRGs), to reveal the origin of their luminosities and to test a proposed evolutionary scenario of ULIRGs. We discovered embedded AGN in some galaxies, but the relative contribution of AGN activity to the total luminosity varies significantly from galaxy to galaxy and has no correlation with the evolutionary sequence as mergers.

We present results of our survey observations of the [C II] 158 μm line emission from the Galactic plane using the Balloon-borne Infrared Carbon Explorer (BICE). Our survey covers a wide area (350° ≲ l ≲ 25°, |b| ≲ 3°) with a spatial resolution of 15′. We employed a new observing method called "fast spectral scanning" to make large-scale observations efficiently. Strong [C II] line emission was detected from almost all areas we observed. In the general Galactic plane, the spatial distribution of the [C II] line emission correlates very well with that of far-infrared continuum emission, but diffuse components are more prominent in the [C II] line emission; the I[C II]/ I ratio is ∼0.6% for diffuse components but is ∼0.2% for compact sources such as active starforming regions. In the Galactic center region, on the other hand, the distribution of the [C II] line emission is quite different from that of the far-infrared continuum emission, and the I[C II]/I ratio is systematically lower there. The FWHM velocity resolution of our instrument is 175 km s , but we determined the central velocity of the line at each observed point very precisely with statistical errors as small as ±6 km s . The longitudinal distribution of the central velocity clearly shows the differential rotation pattern of the Galactic disk and also violent velocity fields around the Galactic center. FIR FIR -1 -1