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The Subaru Seminar is usually held in Room 104 of the Hilo Base Facility, adjacent to the main lobby. Everyone is welcome to attend. If you are interested in giving a seminar, please contact Subaru seminar organizers (Tae-Soo Pyo, Sherry Yeh, Nagayoshi Ohashi) by email : sseminar_at_subaru.naoj.org (please change"_at" to @).

September 24, Thursday, 11:00 am in 104B

" Investigating non-steady processes in warm debris disks "

Daisuke Ishihara

(Nagoya University)


Debris disks are circumstellar dust disks around main-sequence stars. The dust grains in these systems are supplied continuously by collisions of planetesimals or growing proto-planets. Their evolution is conventionally explained by the steady state collisional cascade model. However, mysterious debris disks have been detected by the AKARI mid-IR all-sky survey. They have large amount of warm circumstellar dust even at late (>1 Gyr) stages, which cannot be accounted for by the conventional theory. Some of them show difference between AKARI 18 micron and WISE 22 micron measurements, which indicate the temporal variations of the disk luminosity between 2006 and 2010 or the existence of small grains showing spectral features in the mid-IR. The small grains indicate recent transient events such as the Moon-forming giant impact because they are blown away from the system in a short (~1 yr) timescale. We are now trying follow-up 8-13 micron spectroscopy of the objects using Subaru/COMICS to clarify them. I would like to mention also the AKARI based study of the zodiacal clouds, a faint debris disk of our solar system, and the future perspective on the debris-disk study using the next infrared astronomical satellite, SPICA.


Seminars are also held at JAC, CFHT, and IfA.



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