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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
(Tomonori Usuda, Kumiko S. Usuda, Masayuki Akiyama)
by email : sseminar_at_subaru.naoj.org (please change"_at" to @).
November 26, Monday at 11:00 am
" Molecular Hydrogen Emission from Protoplanetary Disks "
Hideko Nomura (Queen's University, UK)
Thanks to recent high spectral resolution and high sensitivity
observations, it has become possible to detect molecular hydrogen
line emission from protoplanetary disks.
Now, it is believed that in the disks dust particles stick
each other and grow in size, as well as settle towards the disk
midplane. As these processes are thought to be the first step
of planet formation, it is of great interest to find observational
evidence of the dust evolution in the disk.
In this work we have constructed a detailed disk model, taking
into account heating of gas and dust via irradiation from a
central star, as well as the dust coagulation and settling
in the disk. In addition, we have calculated the level populations
of molecular hydrogen and the line emission from the disk.
Our results show that as the dust particles evolve in the disks,
the gas temperature at the disk surface drops because of
inefficient grain photoelectric heating, which leads to a
change in the dominant H2 excitation mechanism from thermal
to UV fluorescent. Therefore, our model calculations suggest
that the dust evolution in protoplanetary
disks could be observable through the H2 line ratios.