研究者詳細 - 小林　浩

論文 - 小林　浩

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Impact erosion model for gravity-dominated planetesimals Open Access

Genda Hidenori, Fujita Tomoaki, Kobayashi Hiroshi, Tanaka Hidekazu, Suetsugu Ryo, Abe Yutaka

ICARUS 294 巻頁： 234-246 2017年9月

A likely detection of a local interplanetary dust cloud passing near the Earth in the AKARI mid-infrared all-sky map Open Access

D. Ishihara, T. Kondo, H. Kaneda, T. Suzuki, K. Nakamichi, S. Takaba, H. Kobayashi, S. Masuda, T. Ootsubo, J. Pyo, T. Onaka

ASTRONOMY & ASTROPHYSICS 603 巻 2017年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：EDP SCIENCES S A

Context. We are creating the AKARI mid-infrared all-sky diffuse maps. Through a foreground removal of the zodiacal emission, we serendipitously detected a bright residual component whose angular size is about 50 degrees x 20 degrees at a wavelength of 9 mu m.
Aims. We investigate the origin and the physical properties of the residual component.
Methods. We measured the surface brightness of the residual component in the AKARI mid-infrared all-sky maps.
Results. The residual component was significantly detected only in 2007 January, even though the same region was observed in 2006 July and 2007 July, which shows that it is not due to the Galactic emission. We suggest that this may be a small cloud passing near the Earth. By comparing the observed intensity ratio of I-9 mu m/I-18 mu m with the expected intensity ratio assuming thermal equilibrium of dust grains at 1 AU for various dust compositions and sizes, we find that dust grains in the moving cloud are likely to be much smaller than typical grains that produce the bulk of the zodiacal light.
Conclusions. Considering the observed date and position, it is likely that it originates in the solar coronal mass ejection ( CME) which took place on 2007 January 25.

DOI： 10.1051/0004-6361/201628954

Web of Science

Size dependence of dust distribution around the earth orbit 査読有り Open Access

T. Ueda, H. Kobayashi, T. Takeuchi, D. Ishihara, T. Kondo, H. Kaneda

Astrophysical Journal 153 巻 ( 5 ) 頁： 232 2017年5月

Faint warm debris disks around nearby bright stars explored by AKARI and IRSF 査読有り Open Access

Daisuke Ishihara, Nami Takeuchi, Hiroshi Kobayashi, Takahiro Nagayama, Hidehiro Kaneda, Shu-ichiro Inutsuka, Hideaki Fujiwara, Takashi Onaka

Astronomy & Astrophysics 601 巻頁： A72 2017年5月

Size Dependence of Dust Distribution around the Earth Orbit Open Access

Ueda Takahiro, Kobayashi Hiroshi, Takeuchi Taku, Ishihara Daisuke, Kondo Toru, Kaneda Hidehiro

ASTRONOMICAL JOURNAL 153 巻 ( 5 ) 2017年5月

Faint warm debris disks around nearby bright stars explored by AKARI and IRSF Open Access

Daisuke Ishihara, Nami Takeuchi, Hiroshi Kobayashi, Takahiro Nagayama, Hidehiro Kaneda, Shu-ichiro Inutsuka, Hideaki Fujiwara, Takashi Onaka

ASTRONOMY & ASTROPHYSICS 601 巻頁： A72 2017年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：EDP SCIENCES S A

Context. Debris disks are important observational clues for understanding planetary-system formation process. In particular, faint warm debris disks may be related to late planet formation near 1 au. A systematic search of faint warm debris disks is necessary to reveal terrestrial planet formation.
Aims. Faint warm debris disks show excess emission that peaks at mid-IR wavelengths. Thus we explore debris disks using the AKARI mid-IR all-sky point source catalog (PSC), a product of the second generation unbiased IR all-sky survey.
Methods. We investigate IR excess emission for 678 isolated main-sequence stars for which there are 18 mu m detections in the AKARI mid-IR all-sky catalog by comparing their fluxes with the predicted fluxes of the photospheres based on optical to near-IR fluxes and model spectra. The near-IR fluxes are first taken from the 2MASS PSC. However, 286 stars with Ks < 4.5 in our sample have large flux errors in the 2MASS photometry due to saturation. Thus we have measured accurate J, H, and Ks band fluxes, applying neutral density (ND) filters for Simultaneous InfraRed Imager for Unbiased Survey (SIRIUS) on IRSF, the phi 1.4m near-IR telescope in South Africa, and improved the flux accuracy from 14% to 1.8% on average.
Results. We identified 53 debris-disk candidates including eight new detections from our sample of 678 main-sequence stars. The detection rate of debris disks for this work is similar to 8%, which is comparable with those in previous works by Spitzer and Herschel.
Conclusions. The importance of this study is the detection of faint warm debris disks around nearby field stars. At least nine objects have a large amount of dust for their ages, which cannot be explained by the conventional steady-state collisional cascade model.

DOI： 10.1051/0004-6361/201526215

Open Access

Web of Science

Detection of Submillimeter-wave [C i] Emission in Gaseous Debris Disks of 49 Ceti and β Pictoris 査読有り Open Access

Aya E Higuchi, Aki Sato, Takashi Tsukagoshi, Nami Sakai, Kazunari Iwasaki, Munetake Momose, Hiroshi Kobayashi, Daisuke Ishihara, Sakae Watanabe, Hidehiro Kaneda, Satoshi Yamamoto

Astrophysical Journal 839 巻 ( 1 ) 頁： L14 2017年4月

Orbital Evolution of Moons in Weakly Accreting Circumplanetary Disks Open Access

Yuri I Fujii, Hiroshi Kobayashi, Sanemichi Z Takahashi, Oliver Gressel

Astronomical Journal 153 巻 ( 4 ) 頁： 194 2017年4月

Detection of Submillimeter-wave [C i] Emission in Gaseous Debris Disks of 49 Ceti and β Pictoris Open Access

Aya E Higuchi, Aki Sato, Takashi Tsukagoshi, Nami Sakai, Kazunari Iwasaki, Munetake Momose, Hiroshi Kobayashi, Daisuke Ishihara, Sakae Watanabe, Hidehiro Kaneda, Satoshi Yamamoto

Astrophysical Journal 839 巻 ( 1 ) 頁： L14 2017年4月

Orbital Evolution of Moons in Weakly Accreting Circumplanetary Disks Open Access

Fujii Yuri I., Kobayashi Hiroshi, Takahashi Sanemichi Z., Gressel Oliver

ASTRONOMICAL JOURNAL 153 巻 ( 4 ) 2017年4月

Evolutionary Description of Giant Molecular Cloud Mass Functions on Galactic Disks 査読有り Open Access

Masato I.N. Kobayashi, Shu-ichiro Inutsuka, Hiroshi Kobayashi, Kenji Hasegawa

Astrophysical Journal 836 巻 ( 2 ) 頁： 175 2017年2月

Evolutionary Description of Giant Molecular Cloud Mass Functions on Galactic Disks Open Access

Masato I. N. Kobayashi, Shu-ichiro Inutsuka, Hiroshi Kobayashi, Kenji Hasegawa

ASTROPHYSICAL JOURNAL 836 巻 ( 2 ) 2017年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IOP PUBLISHING LTD

Recent radio observations show that giant molecular cloud (GMC) mass functions noticeably vary across galactic disks. High-resolution magnetohydrodynamics simulations show that multiple episodes of compression are required for creating a molecular cloud in the magnetized interstellar medium. In this article, we formulate the evolution equation for the GMC mass function to reproduce the observed profiles, for which multiple compressions are driven by a network of expanding shells due to H II regions and supernova remnants. We introduce the cloudcloud collision (CCC) terms in the evolution equation in contrast to previous work (Inutsuka et al.). The computed time evolution suggests that the GMC mass function slope is governed by the ratio of GMC formation timescale to its dispersal timescale, and that the CCC effect is limited only in the massive end of the mass function. In addition, we identify a gas resurrection channel that allows the gas dispersed by massive stars to regenerate GMC populations or to accrete onto pre-existing GMCs. Our results show that almost all of the dispersed gas contributes to the mass growth of pre-existing GMCs in arm regions whereas less than 60% contributes in inter-arm regions. Our results also predict that GMC mass functions have a single power-law exponent in the mass range < 10(5.5) M-circle dot (where M-circle dot represents the solar mass), which is well characterized by GMC self-growth and dispersal timescales. Measurement of the GMC mass function slope provides a powerful method to constrain those GMC timescales and the gas resurrecting factor in various environments across galactic disks.

DOI： 10.3847/1538-4357/836/2/175

Web of Science

Sintering-induced Dust Ring Formation in Protoplanetary Disks: Application to the HL Tau Disk 査読有り

Satoshi Okuzumi, Munetake Momose, Sin-iti Sirono, Hiroshi Kobayashi, Hidekazu Tanaka

Astrophysical Journal 821 巻 ( 2 ) 頁： id 82, 24 2016年4月

From Planetesimals to Planets in Turbulent Protoplanetary Disks. I. Onset of Runaway Growth 査読有り Open Access

Hiroshi Kobayashi, Hidekazu Tanaka, Satoshi Okuzumi

Astrophysical Journal 817 巻 ( 2 ) 頁： id. 105, 10 2016年2月

Resolution Dependence of Disruptive Collisions between Planetesimals in the Gravity Regime 査読有り

H. Genda, T. Fujita, H. Kobayashi, H. Tanaka, Y. Abe

Icarus 262 巻頁： 58 2015年12月

Comet C/2012 S1 (ISON) coma composition at ~4 au from HST observations 査読有り

E. Zubko, G. Videen, D. C. Hines, Y. Shkuratov, V. Kaydash, K. Muinonen, M. M. Knight, M. L. Sitko, C. M. Lisse, M. Mutchler, D. H. Wooden, J.-Y. Li, H. Kobayashi

Planetary and Space Science 118 巻頁： 138 2015年12月

Warm Debris Disks Produced by Giant Impacts During Terrestrial Planet Formation

H. Genda, H. Kobayashi, E. Kokubo

Astrophysical Journal 810 巻頁： 136(8p) 2015年11月

Significant gas-to-dust ratio asymmetry and variation in the disk of HD 142527 and the indication of gas depletion Open Access

Takayuki Muto, Takashi Tsukagoshi, Munetake Momose, Tomoyuki Hanawa, Hideko Nomura, Misato Fukagawa, Kazuya Saigo, Akimasa Kataoka, Yoshimi Kitamura, Sanemichi Z Takahashi, Shu-ichiro Inutsuka, Taku Takeuchi, Hiroshi Kobayashi, Eiji Akiyama, Mitsuhiko Honda, Hideaki Fujiwara, Hiroshi Shibai

Publications of the Astronomical Society of Japan 頁： psv098 2015年11月

Cohesion of Amorphous Silica Spheres: Toward a Better Understanding of The Coagulation Growth of Silicate Dust Aggregates 査読有り

Hiroshi Kimura, Koji Wada, Hiroki Senshu, Hiroshi Kobayashi

Astrophysical Journal 812 巻頁： 1 2015年10月

Planetary and meteoritic Mg/Si and δ30Si variations inherited from solar nebula chemistry 査読有り Open Access

N. Dauphas, F. Poitrasson, C. Burkhardt, H. Kobayashi, K. Kurosawa

Earth and Planetary Science Letter 427 巻頁： 236 2015年10月

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