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The formation of massive stars in dense and cold molecular clouds is a fundamental problem in star formation. In this work, we studied three compact massive star-forming regions, M8E, RAFGL 6366S, and IRAS 18317−0513, to investigate the environment of massive star formation, specifically the possibility of a local feedback process. Our new mid-infrared observations using miniTAO/MAX38 at 31 and 37 μm resolved individual objects in each region and allowed us to obtain their individual luminosities and masses. Together with existence/absence of ultra-compact H ii regions, it is suggested that less-massive objects are more evolved than the more-massive objects in two out of the three regions. Because the objects that are more massive evolve faster, those that are less massive form earlier. This formation trend of local mass-sequential star was first suggested in 0.1 pc-scale massive star-forming regions. Therefore, feedback, such as outflows, jets, or radiative heating, from previously formed lower-mass young stellar objects might affect the environment of parental clouds and lead to next-generation massive young stellar objects.

The Simultaneous-color Wide-field Infrared Multi-object Spectrograph (SWIMS) is one of the 1st generation facility instruments for the University of Tokyo Atacama Observatory (TAO) 6.5 m telescope currently being constructed at the summit of Cerro Chajnantor (5,640 m altitude) in northern Chile. SWIMS has two optical arms, the blue arm covering 0.9–1.4 µm and the red 1.4–2.5 µm, by inserting a dichroic mirror into the collimated beam, and thus is capable of taking images in two filter-bands simultaneously in imaging mode, or whole nearinfrared (0.9–2.5 µm) low-to-medium resolution multi-object spectra in spectroscopy (MOS) mode, both with a single exposure. SWIMS was carried into Subaru Telescope in 2017 for performance evaluation prior to completion of the construction of the 6.5 m telescope, and successfully saw the imaging first light in May 2018 and MOS first light in Jan 2019. After three engineering runs including the first light observations, SWIMS has been accepted as a new PI instrument for Subaru Telescope from the semester S21A until S22B. In this paper, we report on details of on-sky performance of the instrument evaluated during the engineering observations for a total of 7.5 nights.

Since the University of Tokyo Atacama Observatory (TAO) is located in extremely high altitude (5,640 m.a.s.l.), safety management is one of the most important issues for the project. We have developed safety management program for work at the site in order to prevent medical illness for humans. In this program all staff have to take medical examinations such as Electrocardiogram and Hipobaria before their work starts. The results are reviewed by medical doctor. Only authorized staff can be permitted to work at the site. During stay in site, all staff need to always use oxygen supply because there is only half of the oxygen at the site. It is also important to understand physical workload at the site. Our safety staff reviews it and determines necessary resting time for each worker, e.g. great load works need to work 50 minutes and rest 10 minutes. In addition to low air pressure, very low temperature, extremely high UV radiation, and extremely dry atmosphere should be concerned. Our program requests all staff to use winter clothes, sunblock and UV protection sunglasses and a lot of potable water consumption. Keep communication is also very important to secure the safety. Normal telephone communication is not available as well as internet connectivity. We have established satellite communication as well as UHF internal communication for general works and safety coordination with other observatories in Atacama area.

The telescope of the University of Tokyo Atacama Observatory has a primary mirror with a diameter in 6.5m. In order to fabricate the reflecting film initially on the mirror surface and to maintain its optical performance over a long period, a mirror{coating facility will be installed in operation building beside enclosure of the telescope at the summit of Co. Chajnantor (5,640m). The facility consists of mirror coating chamber, cleaning unit for stripping off the old film and clean-up the mirror, and a cart with a lifter for handling the primary mirror cell. Almost all equipment, including the main chamber, was completed by early 2020 and engaged as a mirror coating facility. In order to optimize the coating parameters, comprehensive performance tests were carried out (without primary mirror cell which plays a role of a part of chamber). The evaluation items are how long it takes to reach the target vacuum level and parameters of the current, voltage, and application time during ion bombardment and aluminization. Through iterating test, we were able to obtain each parameter that ultimately met the requirements of the TAO telescope mirror.

One of remarkable features of the University of Tokyo Atacama Observatory (TAO) is an altitude of the site (5,640 m.a.s.l.) While this provides us an excellent condition for astronomical observations, the site development is attended with difficulty due to the hard conditions such as low pressure, low temperature, and limited access. Site preparation for the TAO 6.5 m telescope started in Apr. 2018. Firstly, we have constructed an access road from Pampa la bola plateau (~ 5,000 m.a.s.l) to the summit. It has a width of < 6.5 meter for transportation of telescope parts including the 6.5meter mirror. In order to prevent collapse, angle of side slope is carefully determined based on ground condition and frozen soils. All workers always use oxygen during their work as a measure against hypobaropathy. Since the site temperature in night is lower than 0 degree even in the summer season, it is difficult to ensure quality of foundation concrete if we cast it in-situ. We use pre-cast concrete for the foundation of the telescope, the enclosure, and the support building. The biggest part is the telescope foundation. It has a weight of 600 ton. Considering the transportation to the summit, it is divided into 43 parts and unified at the summit. This is a new trial to make a massive foundation for a large telescope with pre-cast concrete.

The Near-Infrared Cross-dispersed Echelle spectrograph (NICE) is a first light instrument for the TAO 6.5 m telescope. The instrument covers a wavelength range of 0.9 to 2.4 µm and has a resolving power of λ/∆λ ~2,600. NICE was first used on the 1.5 m infrared telescope at the National Astronomical Observatory of Japan from 2001 to 2005 and on the 1.6 m Pirka telescope in Japan from 2009 to 2018. We are now upgrading the cryogenics and computer system for the installation of NICE on the TAO telescope. Here we report on the current status and future schedules of instrumentation updates, control system, and modified specifications of NICE for its transfer to the TAO 6.5 m telescope.

The Mid-Infrared Multi-field Imager for gaZing at the UnKnown Universe (MIMIZUKU) is developed as the first-generation mid-infrared instrument for the University of Tokyo Atacama Observatory (TAO) 6.5-m telescope. MIMIZUKU performs medium-band imaging and low-resolution spectroscopy in 2-38 microns and enables highest-spatial-resolution observations in the long-wavelength mid-infrared beyond 25 microns. In addition, MIMIZUKU has a unique opto-mechanical device called ‘Field Stacker’, which enables us to observe a distant (

Ice rich permafrost is observed at Chajnantor volcano (5,640m a.s.l.) on the University of Tokyo Atacama Observatory (TAO) site. Presence or absence of the permafrost is considered to be requested quite different engineering skills for their infrastructures. Lower altitude boundary is reported to be above 5,079m a.s.l. and maximum active (thawing) layer is 14cm. Minimal seasonal temperature variation, small active layer thickness as the consequences of low numbers of thawing and freezing degree days. Diurnal amplitude results in freeze-thaw cycles only near the surface. Severe frost shattering occurs near the ground surface, producing a dusty, fine-material horizon called a hyper-cryogenic layer. The importance of the snow-covered season for providing great protection for surface energy penetration. Many permafrost hazards are expecting in this construction site such as frost heaving, subsiding, mass movements, erosion, chemical weathering, frost shattering, embankment instability, and

The University of Tokyo Atacama Observatory Project is to construct a 6.5 m infrared-optimized telescope at the summit of Co. Chajnantor (5640 m altitude) in northern Chile. The telescope optics uses a Ritchey-Chretien type layout, with an under-sized secondary mirror to reduce stray light caused by thermal emission from the telescope structure. The primary mirror is a F/1.25 lightweight borosilicate glass (Ohara E6) mirror with honeycomb structure, which is developed by Steward Observatory Richard F. Caris Mirror Lab. The telescope has two Nasmyth foci and two folded-Cassegrain foci, which can be switched by rotating a tertiary mirror. The final focal ratio is 12.2 with a field of view of 25 arcmin in diameter. The telescope mount is a tripod-disk alt-azimuth mount. Both the azimuth and elevation axes are supported by and run on hydrostatic bearings, and they are driven by friction drives with servo motors, which are controlled by the telescope control system. It also controls the hexapod mount of the secondary mirror and the pneumatic actuators of the primary mirror support to keep good image quality during the observation. An off-axis Shack-Hartmann sensor installed in each focus measures the wavefront aberration of the telescope optics, then the misalignment between the secondary and primary mirrors is corrected by adjusting the hexapod mount while other aberrations are corrected by the deformation of the primary mirror. The force distribution of the actuators for correction will be calculated by fitting the wave-front errors with a series of bending modes of the primary mirror.

Institute of Astronomy, Graduate School of Science, the University of Tokyo is promoting the University of Tokyo Atacama Observatory Project, which is to construct an infrared-optimized 6.5m telescope at the summit of Co. Chajnantor (5640m altitude) in northern Chile. The high altitude and dry climate (PWV-0.5mm) realize transparent atmosphere in the infrared wavelength. The project is now approaching the final phase of the construction. Production of major components are almost completed: Production and preassembly test of a telescope mount and dome enclosure have been completed in Japan, and they are being transported to Chile. Three mirrors, the 6.5m primary, 0.9m secondary, and 1.1m-0.75m tertiary mirrors and their support systems have been all completed and tested in the USA. An aluminizing chamber have been fabricated in China, and its tests have been carried out in Japan. Development of two facility instruments, SWIMS and MIMIZUKU, are also completed. They were transported to the Subaru telescope, successfully saw the first light in 2018, and are confirmed to have the performance as designed. On-site construction work at the summit is now underway. Expansion of a summit access road from the ALMA concession was completed in 2019. Installation of foundation will follow, and then erection of the dome enclosure and a control building. The construction works are delayed by COVID-19, and we expect to complete the dome enclosure by Q3 of 2021. The telescope will be installed inside the dome and see the engineering first light by early 2022.

The goal of this paper is to characterise the light variation properties of Mira variables in the Small Magellanic Cloud. We have investigated a combined optical and near infrared multi-epoch dataset of Mira variables based on our monitoring data obtained over 15 years. Bolometric correction relations are formulated for various near-infrared colours. We find that the same bolometric correction equation holds for both the bolometricly brightest and faintest pulsation phases. Period-bolometric magnitude relations and period-colour relations were derived using time-averaged values. Phase lags between bolometric phase and optical and near-infrared phases were detected from the O-rich (the surface C/O number ratio is below unity) Mira variables, while no significant systematic lags were observed in most of the C-rich (the C/O ratio is over unity) ones. Some Miras show colour phase inversions, e.g., $H-K_{\rm s}$ at its bluest while $J-H$ and $J-K_{\rm s}$ are at their reddest values at about the bolometricly brightest phase. Their occurrence conditions were studied but no clear direct or indirect trigger was found. A large NIR colour change unassociated with stellar pulsation was observed in Miras with long secondary periods, and its possible explanation is described., Comment: 20 pages, 22 figures, accepted for publication in MNRAS

A very long term near-infrared variable star survey towards the Large and Small Magellanic Clouds was carried out using the 1.4m InfraRed Survey Facility at the South African Astronomical Observatory. This project was initiated in December 2000 in the LMC, and in July 2001 in the SMC. Since then an area of 3 square degrees along the bar in the LMC and an area of 1 square degree in the central part of the SMC have been repeatedly observed. This survey is ongoing, but results obtained with data taken until December 2017 are reported in this paper. Over more than 15 years we have observed the two survey areas more than one hundred times. This is the first survey that provides near-infrared time-series data with such a long time baseline and on such a large scale. This paper describes the observations in the SMC and publishes a point source photometric catalogue, a variable source catalogue, and time-series data., Comment: 16 pages, 11 figures, accepted for publication in MNRAS

The Mid-Infrared Multi-field Imager for gaZing at the UnKnown Universe (MIMIZUKU) is a mid-infrared camera and spectrograph developed as a first-generation instrument on the University of Tokyo Atacama Observatory (TAO) 6.5-m telescope. MIMIZUKU covers a wide wavelength range from 2 to 38 μm and has a unique optical device called Field Stacker which realizes accurate calibration of variable atmospheric transmittance with a few percent accuracy. By utilizing these capabilities, MIMIZUKU realizes mid-infrared long-term monitoring, which has not been challenged well. MIMIZUKU has three optical channels, called NIR, MIR-S, and MIR-L, to realize the wide wavelength coverage. The MIR-S channel, which covers 6.8–26 μm, has been completed by now. We are planning to perform engineering observations with this channel at the Subaru telescope before the completion of the TAO 6.5-m telescope. In this paper, we report the results of the laboratory tests to evaluate the optical and detector performances of the MIR-S channel. As a result, we confirmed a pixel scale of 0.12 arcsec/pix and a vignetting- free field of view of 2./0 1./8. The instrument throughputs for imaging modes are measured to be 20–30%. Those for N - and Q -band spectroscopy modes are 17 and 5%, respectively. As for the detector performance, we derived the quantum efficiency to be 40–50% in the mid-infrared wavelength region and measured the readout noise to be 3000–6000 electrons, which are larger than the spec value. It was found that this large readout noise degrades the sensitivity of MIMIZUKU by a factor of two.

Simultaneous-color Wide-field Infrared Multi-object Spectrograph, SWIMS, is one of the first generation instruments for University of Tokyo Atacama Observatory 6.5m Telescope where almost continuous atmospheric window from 0.9 to 2.5μm appears, thanks to the high altitude and dry climate of the site. To utilize this excellent condition, SWIMS is capable of simultaneous two-color imaging with a field of view of 9’. in diameter and λ/Δλ ~1000 multi-object spectroscopy at 0.9–2.5μm in a single exposure, utilizing a dichroic mirror inserted in the collimated beam. Here, we overview the instrument, report results of its full-assembly tests in the laboratory and present the future plan.

MIMIZUKU is the first-generation mid-infrared instrument for the university of Tokyo Atacama Observatory (TAO) 6.5-m telescope. MIMIZUKU provides imaging and spectroscopic monitoring capabilities in a wide wavelength range from 2 to 38 μm, including unique bands like 2.7-μm and 30-μm band. Recently, we decided to add spectroscopic functions, KL-band mode (λ= 2.1-4.0 μm; R =λ/Δλ ~ 210) and 2.7-μm band mode ( λ= 2.4-2.95 μm; R ~ 620), and continuous spectroscopic coverage from 2.1 to 26 μm is realized by this update. Their optical designing is completed, and fabrications of optical elements are ongoing. As recent progress, we also report the completion of the cryogenic system and optics. The cryogenic system has been updated by changing materials and structures of thermal links, and the temperatures of the optical bench and detector mounting stages finally achieved required temperatures. Their stability against instrument attitude is also confirmed through an inclination test. As for the optics, its gold-plated mirrors have been recovered from galvanic corrosion by refabrication and reconstruction. Enough image quality and stability are confirmed by room-temperature tests. MIMIZUKU is intended to be completed in this autumn, and commissioning at the Subaru telescope and scientific operations on the TAO telescope are planned in 2017 and around 2019, respectively. In this paper, these development activities and future prospects of MIMIZUKU are reported.

The University of Tokyo Atacama Observatory Project is to construct and operate a 6.5m infrared telescope at the summit of Co. Chajnantor (5640m altitude) in northern Chile, promoted by the Institute of Astronomy of the University of Tokyo. Thanks to the dry climate (PWV~0.5mm) and the high altitude, excellent observation condition in the NIR to MIR wavelengths is achieved. The telescope has two Nasmyth foci where two facility instruments, SWIMS for the near-infrared and MIMIZUKU for the mid-infrared, are installed and two folded- Cassegrain foci for carry-in instruments. All these four foci can be switched by rotating a tertiary mirror. The final focal ratio is 12.2 and the foci have large field-of-view of 25 arcmin in diameter. We adopted a 6.5-m F/1.25 light-weighted borosilicate honeycomb primary mirror and its support system that are developed by Steward Observatory Richard F. Caris Mirror Lab. An enclosure has the shape of carousel, and large ventilation windows with shutters control the wind to flush heat inside the enclosure. A support building with a control room, a mirror coating system and maintenance facilities is located at the side of the enclosure. The mirror coating system consists of a large aluminizing chamber and a mirror washing facility. The operation of the telescope will be remotely carried out from a base facility at San Pedro de Atacama, 50km away from the summit. Development of the two facility instruments has already been completed and they are transported to Hilo, Hawaii in 2017. We are going to carry out engineering observations of those instruments on the Subaru telescope for clearing up technical issues and verifying their performance. The existing summit access road from the ALMA concession area was laid in 2006, however, it is too narrow to carry large components of the telescope and the ancillary facilities such as the primary mirror, its cell, and the aluminizing chamber. The road is being expanded so that it has the width of

We present results on the computational fluid dynamics (CFD) numerical simulations as well as the wind tunnel experiments for the observation facilities of the University of Tokyo Atacama Observatory 6.5m Telescope being constructed at the summit of Co. Chajnantor in northern Chile. Main purpose of this study starting with the baseline design reported in 2014 is to analyze topographic effect on the wind behavior, and to evaluate the wind pressure, the air turbulence, and the air change (ventilation) efficiency in the enclosure. The wind velocity is found to be accelerated by a factor of ~ 1.2 to reach the summit (78 m sec-1 expected at a maximum), and the resulting wind pressure (3,750 N m-2) is used for the framework design of the facilities. The CFD data reveals that the open space below the floor of the facilities works efficiently to drift away the air turbulence near the ground level which could significantly affect the dome seeing. From comparisons of the wind velocity field obtained from the CFD simulation for three configurations of the ventilation windows, we find that the windows at a level of the telescope secondary mirror have less efficiency of the air change than those at lower levels. Considering the construction and maintenance costs, and operation procedures, we finally decide to allocate 13 windows at a level of the observing floor, 12 at a level of the primary mirror, and 2 at the level of the secondary mirror. The opening area by those windows accounts for about 14% of the total interior surface of the enclosure. Typical air change rate of 20-30 per hour is expected at the wind velocity of 1 m sec-1.

The telescope of the University of Tokyo Atacama Observatory has a primary mirror with a diameter in 6.5m. In order to fabricate the reflecting film initially on the mirror surface and to maintain its optical performance over a long period, we have a mirror-coating facility being installed at the summit of Co. Chajnantor (5,640m). The facility consists of a clean booth for stripping off the old film, a mirror coating chamber, and a cart with a lifter for handling the primary mirror. A conventional evaporation system with a metal pre-wetted filament array is adopted for achieving various optical requests. Among the many development items, the fabrication of the transportation and lifting cart has been already completed. It has efficient performance in load capacity (>60 tons) and maximum lifting height (1,750 mm). A cleaning machine having injection nozzles that can realize an efficient and safe cleaning sequence also been completed. A test of the evaporation system using dedicated filaments and filament boxes, which are customized to the TAO's requirements, has shown a uniform coating on a test mirror. An array pattern of the filaments has also been decided based on the coating tests to satisfy the optical specification of the telescope. A detailed design of the main chamber has been almost completed, it is only waiting for the production in the near future.

We have determined interstellar extinction law toward the Galactic center (GC) at the wavelength from 1.2 to 8.0 micron, using point sources detected in the IRSF/SIRIUS near-infrared survey and those in the 2MASS and Spitzer/IRAC/GLIMPSE II catalogs. The central region |l| < 3deg and |b| < 1deg has been surveyed in the J, H and Ks bands with the IRSF telescope and the SIRIUS camera whose filters are similar to the Mauna Kea Observatories (MKO) near-infrared photometric system. Combined with the GLIMPSE II point source catalog, we made Ks versus (Ks - lambda) color-magnitude diagrams where lambda = 3.6, 4.5, 5.8, and 8.0 micron. The Ks magnitudes of bulge red clump stars and the (Ks - lambda) colors of red giant branches are used as a tracer of the reddening vector in the color-magnitude diagrams. From these magnitudes and colors, we have obtained the ratios of total to selective extinction A(Ks)/E(Ks-lambda) for the four IRAC bands. Combined with A(lambda)/A(Ks) for the J and H bands derived by Nishiyama et al., we obtain A(J):A(H):A(Ks):A([3.6]):A([4.5]):A([5.8]):A([8.0])=3.02:1.73:1:0.50:0.39:0.36:0.43 for the line of sight toward the GC. This confirms the flattening of the extinction curve at lambda > 3 micron from a simple extrapolation of the power-law extinction at shorter wavelengths, in accordance with recent studies. The extinction law in the 2MASS JHKs bands has also been calculated, and a good agreement with that in the MKO system is found. In nearby molecular clouds and diffuse interstellar medium, the lack of reliable measurements of the total to selective extinction ratios hampers unambiguous determination of the extinction law; however, observational results toward these lines of sight cannot be reconciled with a single extinction law., 27 pages, 10 figures, Accepted for publication in ApJ

We report on a multi-epoch study of the Fornax dwarf spheroidal galaxy, made with the Infrared Survey Facility, over an area of about 42'x42'. The colour-magnitude diagram shows a broad well-populated giant branch with a tip that slopes down-wards from red to blue, as might be expected given Fornax's known range of age and metallicity. The extensive AGB includes seven Mira variables and ten periodic semi-regular variables. Five of the seven Miras are known to be carbon rich. Their pulsation periods range from 215 to 470 days, indicating a range of initial masses. Three of the Fornax Miras are redder than typical LMC Miras of similar period, probably indicating particularly heavy mass-loss rates. Many, but not all, of the characteristics of the AGB are reproduced by isochrones from Marigo et al. for a 2 Gyr population with a metallicity of Z=0.0025. An application of the Mira period-luminosity relation to these stars yields a distance modulus for Fornax of 20.69+/-0.04 (internal), +/-0.08 (total) (on a scale that puts the LMC at 18.39 mag) in good agreement with other determinations. Various estimates of the distance to Fornax are reviewed.

We present our latest results on near- to mid- infrared observation of SN2006jc at 200 days after the discovery using the Infrared Camera (IRC) on board $AKARI$. The near-infrared (2--5$\mu$m) spectrum of SN2006jc is obtained for the first time and is found to be well interpreted in terms of the thermal emission from amorphous carbon of 800$\pm 10$K with the mass of $6.9\pm 0.5 \times 10^{-5}M_{\odot}$ that was formed in the supernova ejecta. This dust mass newly formed in the ejecta of SN 2006jc is in a range similar to those obtained for other several dust forming core collapse supernovae based on recent observations (i.e., $10^{-3}$--$10^{-5}$$M_{\odot}$). Mid-infrared photometric data with {\it{AKARI}}/IRC MIR-S/S7, S9W, and S11 bands have shown excess emission over the thermal emission by hot amorphous carbon of 800K. This mid-infrared excess emission is likely to be accounted for by the emission from warm amorphous carbon dust of 320$\pm 10$K with the mass of 2.7$^{+0.7}_{-0.5} \times 10^{-3}M_{\odot}$ rather than by the band emission of astronomical silicate and/or silica grains. This warm amorphous carbon dust is expected to have been formed in the mass loss wind associated with the Wolf-Rayet stellar activity before the SN explosion. Our result suggests that a significant amount of dust is condensed in the mass loss wind prior to the SN explosion. A possible contribution of emission bands by precursory SiO molecules in 7.5--9.5$\mu$m is also suggested., Comment: 28 pages, 9 figures. Submitted to the Astrophysical Journal

著者人数: 38名, Accepted: 2014-10-06, 資料番号: SA1150065000

We present the spectra of 14 quasars with a wide coverage of rest wavelengths from 1000 to 7300 A. The redshift ranges from z = 0.061 to 0.555 and the luminosity from M_{B} = -22.69 to -26.32. We describe the procedure of generating the template spectrum of Fe II line emission from the spectrum of a narrow-line Seyfert 1 galaxy I Zw 1 that covers two wavelength regions of 2200-3500 A and 4200-5600 A. Our template Fe II spectrum is semi-empirical in the sense that the synthetic spectrum calculated with the CLOUDY photoionization code is used to separate the Fe II emission from the Mg II line. The procedure of measuring the strengths of Fe II emission lines is twofold; (1) subtracting the continuum components by fitting models of the power-law and Balmer continua in the continuum windows which are relatively free from line emissions, and (2) fitting models of the Fe II emission based on the Fe II template to the continuum-subtracted spectra. From 14 quasars, we obtained the Fe II fluxes in five wavelength bands, the total flux of Balmer continuum, and the fluxes of Mg II, Halpha, and other emission lines, together with the full width at half maxima (FWHMs) of these lines. Regression analysis was performed by assuming a linear relation between any two of these quantities. Eight correlations were found with a confidence level higher than 99%. The fact that six of these eight are related to FWHM or M_{BH} may imply that M_{BH} is a fundamental quantity that controls Gamma or the spectral energy distribution (SED) of the incident continuum, which in turn controls the Fe II emission. Furthermore, it is worthy of noting that Fe II(O1)/Fe II(U1) is found to tightly correlate with Fe II(O1)/Mg II, but not with Fe II(U1)/Mg II., Comment: 50 pages, 10 figures, accepted for publication in ApJ

We report the result of our near-infrared observations (JHKs) for type II Cepheids (including possible RV Tau stars) in galactic globular clusters. We detected variations of 46 variables in 26 clusters (10 new discoveries in seven clusters) and present their light curves. Their periods range from 1.2 d to over 80 d. They show a well-defined period-luminosity relation at each wavelength. Two type II Cepheids in NGC6441 also obey the relation if we assume the horizontal branch stars in NGC6441 are as bright as those in metal-poor globular clusters in spite of the high metallicity of the cluster. This result supports the high luminosity which has been suggested for the RR Lyr variables in this cluster. The period-luminosity relation can be reproduced using the pulsation equation (P sqrt(rho)=Q) assuming that all the stars have the same mass. Cluster RR Lyr variables were found to lie on an extrapolation of the period-luminosity relation. These results provide important constraints on the parameters of the variable stars. Using Two Micron All-Sky Survey (2MASS) data, we show that the type II Cepheids in the Large Magellanic Cloud (LMC) fit our period-luminosity relation within the expected scatter at the shorter periods. However, at long periods ($P>40$ d, i.e. in the RV Tau star range) the LMC field variables are brighter by about one magnitude than those of similar periods in galactic globular clusters. The long-period cluster stars also differ from both these LMC stars and galactic field RV Tau stars in a colour-colour diagram. The reasons for these differences are discussed.

Near-infrared observations have been carried out to survey young stellar objects in the second-largest H II region in the Large Magellanic Cloud, N11. A total area of about 700 arcmin2 is covered in the J, H, and KS bands. We selected a total of 559 OB and 127 Herbig Ae/Be star candidates out of the detected sources based on their near-infrared colors and magnitudes. The existence of these young stellar objects indicates that star formation activity is underway in the whole N11 region. Many Herbig Ae/Be star candidates are distributed around the periphery of the OB association LH 9. Spatial correlations of the OB and Herbig Ae/Be star candidates with the objects observed at other wavelengths (optical, radio continuum, Hα, CO, and X-ray) suggest that the birth of the young stellar populations in peripheral molecular clouds was triggered originally by LH 9. It is likely that the trigger for this star formation was an expanding supershell blown by the OB association. In N11 a new generation of stars would have been formed in the clouds developed from swept-up interstellar medium.

著者人数: 36名, Accepted: 2014-12-10, 資料番号: SA1150021000

The M8.5 object SSSPM J0109−5101 has recently been shown to be both a periodic and a flaring variable, based on optical observations in the extreme red. More than 16 h of monitoring in the near-infrared (NIR) reported here failed to show any variability. Similarly, no NIR variability could be detected in intensive monitoring of three other suspected optical variables. This paper also reports on photometry of half a dozen targets monitored over a few weeks, and on the comparison of intensive monitoring at different epochs. In only one case, that of the

We present the result of a near-infrared (J H Ks) survey along the Galactic plane, -10.5deg < l < +10.5deg and b=+1.0deg, with the IRSF 1.4m telescope and the SIRIUS camera. Ks vs. H-Ks color-magnitude diagrams reveal a well-defined population of red clump (RC) stars whose apparent magnitude peak changes continuously along the Galactic plane, from Ks=13.4 at l=-10deg to Ks=12.2 at l=+10deg after dereddening. This variation can be explained by the bar-like structure found in previous studies, but we find an additional inner structure at |l| < 4deg, where the longitude - apparent magnitude relation is distinct from the outer bar, and the apparent magnitude peak changes by only 0.1 mag over the central 8deg. The exact nature of this inner structure is as yet uncertain., 8 pages, 4 figures. accepted by ApJL

著者人数: 14名, Accepted: 2004-10-20, 資料番号: SA1003336000

Seventeen globular clusters in the Large and Small Magellanic Clouds were observed in the mid-infrared wavelength region with the ISOCAM instrument on board the Infrared Space Observatory (ISO). Observations were made using the broadband filters LW1, LW2, and LW10, corresponding to the effective wavelengths of 4.5, 6.7, and 12 mum, respectively. We present the photometry of point sources in each cluster, as well as their precise positions and finding charts.

The data of 8,852 and 2,927 variable stars detected by OGLE survey in the Large and Small Magellanic Clouds are presented. They are cross-identified with the SIRIUS JHK survey data, and their infrared properties are discussed. Variable red giants are well separated on the period-J - K plane, suggesting that it could be a good tool to distinguish their pulsation mode and type.

We cross-correlated the OGLE-II database with the SIRIUS JHK survey data in the Large Magellanic Cloud (LMC). After eliminating obvious spurious variables, we determined the pulsation periods for 9 681 stars by applying the Phase Dispersion Minimization (PDM) technique to the OGLE-II data. Based on these data, we studied the period-K magnitude (PK) relations of variable stars in the LMC and found a new sequence. Comparison between the theoretical pulsation model (Wood & Sebo 1996) and observational data suggests that the variable stars on the new sequence are Mira variables pulsating in the first overtone mode.

We found that the OGLE database contains most AGB stars associated with the SMC cluster NGC 419. Combining these data with our near-infrared (NIR) data, we obtained the following results: 1) Almost all AGB stars above the TRGB are variables. 2) Large amplitude variables tend to show more regular light curves. 3) Only the tip AGB stars (in this case, carbon stars) increase their amplitudes with their J – K colors and only the most evolved ones can become large amplitude (Mira-like) variables. 4) AGB variables may explain the sequences found by Wood et al. (1999).

The first results of our ongoing near-infrared (NIR) survey of the variable red giants in the Large Magellanic Cloud, using the Infrared Survey Facility (IRSF) and the SIRIUS infrared camera, are presented. Many very red stars were detected and found that most of them are variables. In the observed colour-magnitude diagram ($J-K, K$) and the stellar $K$ magnitude distribution, the tip of the first giant branch (TRGB), where helium burning in the core starts, is clearly seen. Apart from the genuine AGB variables, we found many variable stars at luminosities around the TRGB. From this result, we infer that a substantial fraction of them are RGB variables., 5 pages, 3 figures; accepted for publication in MNRAS Letters

The first results of a study of the the dwarf spheroidal galaxy, Leo I, using the new Japanese-South African Infrared Survey Facility (IRSF) are presented. J,H,K_{s} observations show that most, if not all, of at least the top one magnitude of the AGB is populated by carbon stars. These objects form a tight sequence in the K_{s} - (J-K_{s}) plane. In addition there are five very red objects which are believed to be dust enshrouded AGB stars. They have Mbol near -5.0 and are at the AGB tip. Comparison with carbon Miras in Magellanic Cloud clusters and taking into account other evidence on the ages and metallicities of Leo I populations suggests that these obscured stars belong to the youngest significant population of Leo I and have ages of ~2 Gyr. Some of them can be shown to be variable.

大動脈-大腿動脈バイパス術41例54肢(AF群),大腿-大腿交叉バイパス術26例26肢(FF群),腋窩-大腿動脈バイパス術6例7肢(AxF群),大腿-膝上膝窩動脈バイパス術37例39肢(FP群)の遠隔成績を検討した.AF群に比し,FF群では有意に高齢で,AxF群,FF群ではFontaine III, IV度の割合が有意に多く,術前ABIも有意に低かった.5年1次開存率はAF群94.7%,FF群91.3%,FP群64.3%であったが,FP群では跛行症例では82.5%で,救肢症例では43.3%であった.5年2次開存率はAF群94.6%,FF群91.3%,FP群83.3%であった.グラフト閉塞症例は全例が男性で喫煙歴を有していたほか,血栓傾向やrun off不良,術後薬物療法の不徹底が関係していた.グラフト閉塞患者12例のうち2例で下肢切断となり,手術例全例の肢切断回避率は98.4%であった.

症例は65歳,男性.約6m高の屋根より転落し,深昏睡,ショックで入院した.頭蓋底骨折,右全肋骨骨折,血気胸を含む多発外傷を保存的に治療し,約2週間で意識障害と呼吸不全が軽快したが,経過中に下行大動脈瘤を生じ6.5cmに増大した.合併病変による危険を考え,ステントグラフト内挿術を施行し,瘤径は3ヵ月で4.6cmに縮小した.

A new single-electron (SE) circuit mimicking the foraging behavior of a honeybee swarm is proposed. Recently, a "nature-inspired" or "biomimetic" technology has been attracting attention for developing innovative functional systems applying emerging nanoscale devices. In particular, the foraging behavior of honeybees is focused on as an architecture for a SE circuit. Honeybees show two foraging behaviors, namely, a probability search and a "waggle dance" (sharing information). By combining these behaviors, it can be considered that the foraging behavior is a unique information-processing act. For constructing a new system, a SE circuit mimicking the behavior was designed, constructed, and simulated. The SE circuit was constructed by assuming that the information that honeybees share corresponds to the operation of the circuit. The results of the simulation confirmed that the SE circuit mimics the information-sharing behavior of honeybees. Namely, the proposed honeybee-inspired SE circuit can perform functional information processing.

The Simultaneous-color Wide-field Infrared Multi-object Spectrograph, SWIMS, is a first-generation near-infrared instrument for the University of Tokyo Atacama Observatory (TAO) 6.5m Telescope now being constructed in northern Chile. To utilize the advantage of the site that almost continuous atmospheric window appears from 0.9 to 2.5 μm, the instrument is capable of simultaneous two-color imaging with a field-of-view of 9.′6 in diameter or λ/uλ 1000 multi-object spectroscopy at 0.9–2.5 μm in a single exposure. The instrument has been trans- ported in 2017 to the Subaru Telescope as a PI-type instrument for carrying out commissioning observations before starting science operation on the 6.5m telescope. In this paper, we report the latest updates on the instrument and present preliminary results from the on-sky performance verification observations.

A basic design of enclosure and support facilities for the University of Tokyo Atacama observatory (TAO) 6.5-m telescope is described in this paper. The enclosure facility has a carousel shape with an open-space near the ground surface. The upper carousel rotates independently of the telescope. Horizontally opened slit doors, a dozen ventilation windows, wind and moon shields, and an overhead bridge-crane are equipped. For safety reasons, most of maintenance walkways are placed inside of the enclosure facility. An observation floor of the enclosure facility is connected to the support facility via a bridge for maintenance of observation instruments and a primary mirror of the telescope. Air inside of the enclosure and support facilities is exhausted to an underground tunnel.

The University of Tokyo Atacama Observatory (TAO) is a project to construct a 6.5-meter telescope optimized for infrared observations at the summit of Co. Chajnantor, 5,640 m altitude. The high altitude and low water vapor (0.5mm in 25% percentile) of the site provide wide wavelength coverage from 0.3 to 38 micron including continuous window from 0.9 to 2.5 micron and new windows at wavelength longer than 25 micron. We report on the design and the current status of the mirror, the telescope, the summit and the base facilities in this paper.

We here summarize the design and the current fabrication status for the University of Tokyo Atacama Observatory (TAO) 6.5-m telescope. The TAO telescope is operated at one of the best sites for infrared observations, at the summit of Co. Chajnantor in Chile, and is optimized for infrared observations. The telescope mount, mirrors, and mirror support systems are now at the final design phase. The mechanical and optical designs are done by following and referring to those of the Magellan telescopes, MMT, and Large Binocular Telescope. The final focal ratio is 12.2. The field-of-view is as wide as 25 arcmin in diameter and the plate scale is 2.75 arcsec mm −1 . The F/1.25 light-weighted borosilicate (Ohara E6) honeycomb primary mirror is adopted and being fabricated by the Steward Observatory Mirror Laboratory. The primary mirror is supported by 104 loadspreaders bonded to the back surface of the mirror and 6 adjustable hardpoints. The mirror is actively controlled by adjusting the actuator forces based on the realtime wavefront measurement. The actuators are optimized for operation at high altitude of the site, 5640-m above the sea level, by considering the low temperature and low air pressure. The mirror is held in the primary mirror cell which is used as a part of the vacuum chamber when the mirror surface is aluminized without being detached from the cell. The pupil is set at the secondary mirror to minimize infrared radiation into instruments. The telescope has two Nasmyth foci for near-infrared and mid-infrared facility instruments (SWIMS and MIMIZUKU, respectively) and one folded-Caseggrain focus for carry-in instruments. At each focus, autoguider and wavefront measurement systems are attached to achieve seeing-limited image quality. The telescope mount is designed as a tripod-disk type alt-azimuth mount. Both the azimuthal and elevation axes are supported by and run on the hydrostatic bearings. Friction drives are selected for these axis drives. The telescope mount structure and primary mirror support as well as the mirrors are under thermal control and maintained at ambient air temperature to minimize the mirror seeing.

The MIMIZUKU is the first-generation mid-infrared instrument for the TAO 6.5-m telescope. It challenges to prove the origin of dust and the formation of planets with its unique capabilities, wide wavelength coverage and precise calibration capability. The wide wavelength coverage (2-38 μm) is achieved by three switchable cameras, NIR, MIR-S, and MIR-L. The specifications of the cameras are revised. A 5μm-cutoff HAWAII-1RG is decided to be installed in the NIR camera. The optical design of the MIR-L camera is modified to avoid detector saturation. Its final F-number is extended from 5.2 to 10.5. With these modifications, the field of view of the NIR and MIR-L camera becomes 1.2’ × 1.2’ and 31” × 31”, respectively. The sensitivity of each camera is estimated based on the revised specifications. The precise calibration is achieved by the “Field Stacker” mechanism, which enables the simultaneous observation of the target and the calibration object in different fields. The up-and-down motion of the cryostat (~ 1 t), critical for the Field Stacker, is confirmed to have enough speed (4 mm/s) and position accuracy (~ 50 μm). A control panel for the Field Stacker is completed, and its controllers are successfully installed. The current specifications and the development status are reported.

We present ISO (Infrared Space Observatory) observations of the planetary nebula Lindsay 305 (L 305) in the Small Magellanic Cloud. L 305 is very prominent in the ISOCAM frames at 6.75 and 11.5 $\mu$m, although it is under the detection limit at 4.5 $\mu$m. The obtained spectral energy distribution shows a strong mid-IR excess, which, depending on the amount of energy radiated at wavelengths longer than 11.5 $\mu$m, may be as large as $\sim 1500 L_{\odot}$. However, since an accurate estimate of the total nebular luminosity is not available up to date, the evolutionary status of L 305 can not yet be constrained precisely., Comment: 4 pages, 2 figures, to appear in the Publications of the Astronomical Society of Japan

ABSTRA C T We report on the light variations of the infrared stars that were discovered recently in the Magellanic clusters NGC 419, 1783 and 1978. Their periods, of 528, 458 and 491 days, are among the longest known for carbon-rich Mira variables in the Clouds. All three IR stars were found to lie on the extension of the period‐Mbol relation derived from the shorterperiod C-rich Miras while they were 0.45‐0.70 mag fainter than the extension of the period‐ MK relation. Their main sequence masses were determined by isochrone fitting to be 1.5‐ 1.6 M(, consistent with the prediction of the evolutionary models of Vassiliadis & Wood.