51 research outputs found

    The Subaru Deep Field Project: Lymanα\alpha Emitters at Redshift of 6.6

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    We present new results of a deep optical imaging survey using a narrowband filter (NB921NB921) centered at λ=\lambda = 9196 \AA ~ together with BB, VV, RR, ii^\prime, and zz^\prime broadband filters in the sky area of the Subaru Deep Field which has been promoted as one of legacy programs of the 8.2m Subaru Telescope. We obtained a photometric sample of 58 Lyα\alpha emitter candidates at zz \approx 6.5 -- 6.6 among 180\sim 180 strong NB921NB921-excess (zNB921>1.0z^\prime - NB921 > 1.0) objects together with a color criterion of iz>1.3i^\prime - z^\prime > 1.3. We then obtained optical spectra of 20 objects in our NB921NB921-excess sample and identified at least nine Lyα\alpha emitters at z6.5z \sim 6.5 -- 6.6 including the two emitters reported by Kodaira et al. (2003). Since our Lyα\alpha emitter candidates are free from strong amplification of gravitational lensing, we are able to discuss their observational properties from a statistical point of view. Based on these new results, we obtain a lower limit of the star formation rate density of ρSFR5.5×104\rho_{\rm SFR} \simeq 5.5 \times 10^{-4} h0.7h_{0.7} MM_\odot yr1^{-1} Mpc3^{-3} at z6.6z \approx 6.6, being consistent with our previous estimate. We discuss the nature of star-formation activity in galaxies beyond z=6z=6.Comment: 49 pages, 16 figures, PASJ, Vol. 57, No. 1, in pres

    Subaru near infrared coronagraphic images of T Tauri

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    High angular resolution near-infrared (JHK) adaptive optics images of T Tau were obtained with the infrared camera Coronagraphic Imager with Adaptive Optics (CIAO) mounted on the 8.2m Subaru Telescope in 2002 and 2004. The images resolve a complex circumstellar structure around a multiple system. We resolved T Tau Sa and Sb as well as T Tau N and S. The estimated orbit of T Tau Sb indicates that it is probably bound to T Tau Sa. The K band flux of T Tau S decreased by ˜ 1.7 Jy in 2002 November compared with that in 2001 mainly because T Tau Sa became fainter. The arc-like ridge detected in our near-infrared images is consistent with what is seen at visible wavelengths, supporting the interpretation in previous studies that the arc is part of the cavity wall seen relatively pole-on. Halo emission is detected out to ˜2\u27\u27from T Tau N. This may be light scattered off the common envelope surrounding the T Tauri multiple system

    Current Performance and On-Going Improvements of the 8.2 m Subaru Telescope

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    An overview of the current status of the 8.2 m Subaru Telescope constructed and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of Japan is presented. The basic design concept and the verified performance of the telescope system are described. Also given are the status of the instrument package offered to the astronomical community, the status of operation, and some of the future plans. The status of the telescope reported in a number of SPIE papers as of the summer of 2002 are incorporated with some updates included as of 2004 February. However, readers are encouraged to check the most updated status of the telescope through the home page, http://subarutelescope.org/index.html, and/or the direct contact with the observatory staff.Comment: 18 pages (17 pages in published version), 29 figures (GIF format), This is the version before the galley proo

    A Young Brown Dwarf Companion to DH Tauri

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    We present the detection of a young brown dwarf companion DH Tau B associated with the classical T Tauri star DH Tau. Near-infrared coronagraphic observations with CIAO on the Subaru Telescope have revealed DH Tau B with H = \~15 mag located at 2.3" (330 AU) away from the primary DH Tau A. Comparing its position with a Hubble Space Telescope archive image, we confirmed that DH Tau A and B share the common proper motion, suggesting that they are physically associated with each other. The near-infrared color of DH Tau B is consistent with those of young stellar objects. The near-infrared spectra of DH Tau B show deep water absorption bands, a strong K I absorption line, and a moderate Na I absorption line. We derived its effective temperature and surface gravity of Teff = 2700 -- 2800 K and log g = 4.0--4.5, respectively, by comparing the observed spectra with synthesized spectra of low-mass objects. The location of DH Tau B on the HR diagram gives its mass of 30 -- 50 M_Jupiter.Comment: 10 pages, 14 figures, 1 table, accepted for publication in Ap

    High resolution imaging polarimetry of HL Tau and magnetic field structure

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    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 pattern dominated by scattered light. In the H and K bands the central source becomes visible and its polarisation appears to be dominated by dichroic extinction, with a position angle inclined by ~40 degrees to the disc axis. The polarisation pattern of the environs on scales up to 200 AU is consistent with the same dichroic extinction signature superimposed on the centrosymmetric scattering pattern. These data can be modelled with a magnetic field which is twisted on scales from tens to hundreds of AU, or alternatively by a field which is globally misaligned with the disc axis. A unique solution to the field structure will require spatially resolved circular polarisation data. The best fit Monte Carlo model indicates a shallow near infrared extinction law. When combined with the observed high polarisation and non-negligible albedo these constraints can be fitted with a grain model involving dirty water ice mantles in which the largest particles have radii slightly in excess of 1 um. The best fit model has an envelope structure which is slightly flattened on scales up to several hundred AU. Both lobes of the bipolar outflow cavity contain a substantial optical depth of dust (not just within the cavity walls). Curved, approximately parabolic, cavity walls fit the data better than a conical cavity. The small inner accretion disc observed at millimetre wavelengths is not seen at this spatial resolution.Comment: Accepted by MNRAS, 21 pages, 10 figure

    IAU Regions and Regional Astronomy

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    CHAPTER II: TWENTY NINETH GENERAL ASSEMBLY BUSINESS SESSIONS

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