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SUBARU EXPLORATIONS OF EXO-SOLAR PLANETS AND DISKS
TAMURA MOTOHIDE The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.2
To date, more than 150 exo-solar planets have been observed by various methods such as spectroscopic, photometric, astrometric, gravitational lensing, pulsar timing methods. However, all these are indirect methods; they do not directly image the planets. Only free-floating planets or their 'ana-log' have been directly detected so far. Thus the next milestone is the direct imaging of any kinds of planetary mass objects orbiting around normal (young) stars, which might have been associated with protoplanetary disks, the sites of planet formation. I will describe some SUBARU efforts to detect self-luminous young giant planets as companions as well as direct imaging of the protoplanetary disks of ${\~}$100 AU size. The results of near-infrared coronagraphic imaging with adaptive optics are briefly presented on AB Aur, HD 142527, T Tau, and DH Tau. Our results demonstrate the importance of high-resolution (${\~}$0.1 arcsec) direct imaging over indirect observations such as modeling based on spectral energy distributions. The SUBARU observations are a prelude to ALMA from the morphological point of view.
A First Look at BISTRO Observations of the <i>ρ</i> Oph-A core
Kwon, Jungmi,Doi, Yasuo,Tamura, Motohide,Matsumura, Masafumi,Pattle, Kate,Berry, David,Sadavoy, Sarah,Matthews, Brenda C.,Ward-Thompson, Derek,Hasegawa, Tetsuo,Furuya, Ray S.,Pon, Andy,Francesco, Jame American Astronomical Society 2018 The Astrophysical Journal Vol.859 No.1
Near-infrared Polarimetry of the Outflow Source AFGL 6366S: Detection of Circular Polarization
Kwon, Jungmi,Nakagawa, Takao,Tamura, Motohide,Hough, James H.,Kandori, Ryo,Choi, Minho,Kang, Miju,Cho, Jungyeon,Nakajima, Yasushi,Nagata, Tetsuya American Institute of Physics 2018 The Astronomical journal Vol.156 No.1
First Near-infrared Imaging Polarimetry of Young Stellar Objects in the Circinus Molecular Cloud
Kwon, Jungmi,Nakagawa, Takao,Tamura, Motohide,Hough, James H.,Choi, Minho,Kandori, Ryo,Nagata, Tetsuya,Kang, Miju Published by the University of Chicago Press for t 2018 The Astrophysical journal Supplement series Vol.234 No.2
<P>We present the results of near-infrared (NIR) linear imaging polarimetry in the J, H, and K-s bands of the low-mass star cluster-forming region in the Circinus Molecular Cloud Complex. Using aperture polarimetry of point-like sources, positive detection of 314, 421, and 164 sources in the J, H, and Ks bands, respectively, was determined from among 749 sources whose photometric magnitudes were measured. For the source classification of the 133 point-like sources whose polarization could be measured in all 3 bands, a color-color diagram was used. While most of the NIR polarizations of point-like sources are well-aligned and can be explained by dichroic polarization produced by aligned interstellar dust grains in the cloud, 123 highly polarized sources have also been identified with some criteria. The projected direction on the sky of the magnetic field in the Cir-MMS region is indicated by the mean polarization position angles (70 degrees) of the point-like sources in the observed region, corresponding to approximately 1.6 x 1.6 pc(2). In addition, the magnetic field direction is compared with the outflow orientations associated with Infrared Astronomy Satellite sources, in which two sources were found to be aligned with each other and one source was not. We also show prominent polarization nebulosities over the Cir-MMS region for the first time. Our polarization data have revealed one clear infrared reflection nebula (IRN) and several candidate IRNe in the Cir-MMS field. In addition, the illuminating sources of the IRNe are identified with near-and mid-infrared sources.</P>
Soam, A.,Kwon, Jugmi,Maheswar, G.,Tamura, Motohide,Lee, Chang Won IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.803 No.2
<P>LDN 328 is cited as an example of a fairly isolated clump contracting to form multiple sub-cores, possibly through gravitational fragmentation. In one of these sub-cores, a proto-brown dwarf (L328-IRS) candidate is in the process of formation through the self-gravitating contraction, similar to the formation scenario of a low-mass star. We present results of our optical and near-infrared polarization observations of regions toward LDN 328. This is the first observational attempt to map the magnetic field geometry of a cloud harboring a proto-brown dwarf candidate associated with a sub-parsec-scale molecular outflow. On a parsec scale, the magnetic field is found to follow the curved structure of the cloud showing a head-tail morphology. The magnetic field is found to be well ordered over a 0.02-0.2 pc scale around L328-IRS. Taking into account the uncertainties in the determination of position angles, the projected angular offset between the magnetic field direction and the outflow axis is found to be in the range of 0 degrees-70 degrees. Considering outflow to be the proxy for the rotation axis, the result obtained in this study implies that the rotation axis in L328 is preferably parallel to the local magnetic field. The magnetic field strength estimated in the close vicinity of L328-IRS is similar to 20 mu G. Results from the present study suggest that the magnetic field may be playing a vital role even in the cores that are forming sub-stellar sources.</P>