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HIGH ANGULAR RESOLUTION [Fe II] λ1.644 μ SPECTROSCOPY OF YSOS WITH SUBARU TELESCOPE
PYO TAE-SOO,HAYASHI MASAHIKO,NAOTO KOBAYASHI,TERADA HIROSHI,TOKUNAGA ALAN T. The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.2
We present results of the velocity-resolved spectroscopy of the [Fe II] $\lambda$1.644${\mu}m$ emission toward outflow sources with the Subaru Telescope at the angular resolution of 0.apos;16 ${\~}$ 0.apos;5 arcseconds. The observed sources are L1551 IRS 5, DG Tau, HL Tau and RW Aur, which are located in the Taurus-Aurigae Molecular Cloud, one of the closest star forming regions (0.apos;1 = 14 AU). We were able to resolve outflow structure in the vicinity of the sources at a scale of a few tens of AU. The position-velocity diagram of each object shows two velocity components: the high velocity component (HVC: 200 - 400 km $s^{-l}$) and the low velocity component (LVC: 50 - 150 km $s^{-l}$), which are clearly distinct in space and velocity. The HVC may be a highly collimated jet presumed from its narrow velocity width and high velocity. The LVC, on the other hand, may be a widely opened disk wind inferred from its broad velocity width and low velocity. The spectrum taken perpendicular to the L1551 IRS 5 outflow at its base shows that the LVC has a spatially wide subcomponent, supporting the above interpretation. We demonstrated that the [Fe II] 1.644 $\mu$ spectroscopy is a very powerful tool for the studies of fast jets and winds that directly emanate from star-disk systems.
Kenji Horie,Yukiyasu Tsutsumi,Hyeoncheol Kim,Moonsup Cho,Hiroshi Hidaka,Kentaro Terada 한국지질과학협의회 2009 Geosciences Journal Vol.13 No.3
Zircon U–Pb geochronology was applied to a migmatitic gneiss in the Busan gneiss complex, Gyeonggi massif, Korea. 207Pb/206Pb ages of concordant zircon grains reveal that overgrowth rims with Th/U ratios lower than 0.1 formed at 1937 ± 6 Ma during the migmatization and mantled the inherited cores of ca. 3500–2200 Ma. The 207Pb/206Pb age of the rims is consistent with the monazite Th–total Pb age (ca. 1938 Ma), suggesting that the rims are the product of Paleoproterozoic regional metamorphism. Our zircon age data are not sufficient for discerning the tectonic affinity of the Busan gneiss complex belonging to either Gyeonggi or Yeongnam massif. However, consistency of these ages with the ca. 1930 Ma Pb–Pb age reported from the Bagdalryeong gneiss complex, Gyeonggi massif, supports the tectonic model that the Busan gneiss complex is a part of the Gyeonggi massif. Discordant U–Pb data obtained from the zircon rims (293 ± 31 Ma) and the monazite Th–total Pb age (ca. 289 Ma) suggest that the Busan gneiss complex was affected by the Early Permian regional metamorphism during the Ogcheon (Okcheon) Orogeny. Therefore, we conclude that the Busan gneiss complex is a part of the Gyeonggi massif occurring as either a basement rock of the Ogcheon (Okcheon) metamorphic rocks, or a tectonically emplaced, exotic piece affected by the Early Permian Ogcheon (Okcheon) metamorphism. In addition, our U–Pb data suggest that the Busan complex is possibly linked with the Hida–Oki terrane in Japanese Islands.
INTERPRETATION OF (596) SCHEILA'S TRIPLE DUST TAILS
Ishiguro, Masateru,Hanayama, Hidekazu,Hasegawa, Sunao,Sarugaku, Yuki,Watanabe, Jun-ichi,Fujiwara, Hideaki,Terada, Hiroshi,Hsieh, Henry H.,Vaubaillon, Jeremie J.,Kawai, Nobuyuki,Yanagisawa, Kenshi,Kuro IOP Publishing 2011 ASTROPHYSICAL JOURNAL LETTERS - Vol.741 No.1
<P>Strange-looking dust cloud around asteroid (596) Scheila was discovered on 2010 December 11.44-11.47. Unlike normal cometary tails, it consisted of three tails and faded within two months. We constructed a model to reproduce the morphology of the dust cloud based on the laboratory measurement of high-velocity impacts and the dust dynamics. As a result, we succeeded in reproducing the peculiar dust cloud by an impact-driven ejecta plume consisting of an impact cone and downrange plume. Assuming an impact angle of 45 degrees, our model suggests that a decameter-sized asteroid collided with (596) Scheila from the direction of (alpha(im), delta(im)) = (60 degrees, -40 degrees) in J2000 coordinates on 2010 December 3. The maximum ejection velocity of the dust particles exceeded 100 m s(-1). Our results suggest that the surface of (596) Scheila consists of materials with low tensile strength.</P>
OBSERVATIONAL EVIDENCE FOR AN IMPACT ON THE MAIN-BELT ASTEROID (596) SCHEILA
Ishiguro, Masateru,Hanayama, Hidekazu,Hasegawa, Sunao,Sarugaku, Yuki,Watanabe, Jun-ichi,Fujiwara, Hideaki,Terada, Hiroshi,Hsieh, Henry H.,Vaubaillon, Jeremie J.,Kawai, Nobuyuki,Yanagisawa, Kenshi,Kuro IOP Publishing 2011 ASTROPHYSICAL JOURNAL LETTERS - Vol.740 No.1
<P>An unexpected outburst was observed around (596) Scheila in 2010 December. We observed (596) Scheila soon after the impact using ground-based telescopes. We succeeded in the detection of a faint linear tail after 2011 February, which provides a clue to determine the dust ejection date. It is found that the dust particles ranging from 0.1-1 mu m to 100 mu m were ejected into the interplanetary space impulsively on December 3.5 +/- 1.0 day. The ejecta mass was estimated to be (1.5-4.9) x 10(8) kg, suggesting that an equivalent mass of a 500-800 m diameter crater was excavated by the event. We also found that the shape of the light curve changed after the impact event probably because fresh material was excavated around the impact site. We conclude that a decameter-sized asteroid collided with (596) Scheila only eight days before the discovery.</P>