Takahiro Naoi

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On the basis of the near infrared observations of bulge red clump stars near the Galactic center, we have determined the galactocentric distance to be R0 = 7.52± 0.10 (stat) ±0.35 (sys) kpc. We observed the red clump stars at | l |. 1. 0 and 0. 7 .| b |. 1. 0 with the IRSF 1.4 m telescope and the SIRIUS camera in the H and KS bands. After extinction and(More)
We present high quality near infrared imaging polarimetry of HL Tau at 0.4 to 0.6 arcsec resolution, obtained with Subaru/CIAO and UKIRT/IRCAM. 3-D Monte Carlo modelling with aligned oblate grains is used to probe the structure of the circumstellar envelope and the magnetic field, as well as the dust properties. At J band the source shows a centrosymmetric(More)
We have determined the ratios of total to selective extinction in the nearinfrared bands (J,H,KS) toward the Galactic center from the observations of the region | l |. 2. 0 and 0. 5 .| b |. 1. 0 with the IRSF telescope and the SIRIUS camera. Using the positions of red clump stars in color-magnitude diagrams as a tracer of the extinction and reddening, we(More)
Studies of the structure and evolution of protoplanetary disks are important for understanding star and planet formation. Here we present the direct image of an interacting binary protoplanetary system. Both circumprimary and circumsecondary disks are resolved in the near-infrared. There is a bridge of infrared emission connecting the two disks and a long(More)
We determine and compare the color excess ratios EJ H /EH KS for the Ophiuchi and Chamaeleon dark clouds with the J -, H-, and Ks-band simultaneous camera, SIRIUS, on the IRSF 1.4 m telescope at SAAO. Determining accurate ratios is indispensable for discussions of the extinction law. However, previous surveys suffered from uncertainties in transforming one(More)
We present the result of a near-infrared ( ) survey along the Galactic plane, and JHK 10 .5 ≤ l ≤ 10 .5 s , with the IRSF 1.4 m telescope and the SIRIUS camera. versus color-magnitude diagrams b p 1 K H K s s reveal a well-defined population of red clump stars whose apparent magnitude peak changes continuously along the Galactic plane, from at to at after(More)
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(More)
We have developed a digital fast Fourier transform spectrometer made of an analog-to-digital converter (ADC) and a field-programmable gate array (FPGA). The base instrument has independent ADC and FPGA modules, which allow us to implement different spectrometers in a relatively easy manner. Two types of spectrometers have been instrumented: one with 4.096(More)
We have conducted J , H , and KS imaging observations for the Coalsack Globule 2 with the SIRIUS infrared camera on the IRSF 1.4 m telescope at SAAO, and determined the color excess ratio, EJ−H/EH−KS . The ratio is determined in the same photometric system as our previous study for the ρ Oph and Cha clouds without any color transformation; this enables us(More)
Ryo Kandori Department of Astronomical Science, Graduate University for Advanced Studies (Sokendai), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Present address: Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan (kandori@optik.mtk.nao.ac.jp) Yasushi Nakajima, Motohide Tamura,(More)
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