| date: | 2008 Oct 7(Tue) 16:30 - 18:00 |
| room: |
Hokkaido University, Science Bldg. #8, Cosmo-studio (8-2-01), Kobe University, Shizen Bldg. #3, room 508. (This seminar is a teleconference by the use of video-conferencing system.) |
| speaker: | Dr. Munetaka Ueno (University of Tokyo) |
| title: |
AKARI mission program; "From a star forming region to the interplanetary dust" |
| abstract: |
I will introduce preliminary results of AKARI observations on
the star forming regions and on the interplanetary dust. Over the last decade, submm astronomy has revealed a class of heavily embedded, pre-stellar cores that are "invisible" or faint at infrared wavelengths. These low-mass Class 0 and Class I sources are beginning their main accretion phase prior to collapse, and hence represent the earliest and most exciting stages of star-formation. We conducted a significant unbiased census of star-forming cores in a large number of molecular clouds as part of a sensitive large area galactic plane survey with AKARI. AKARI survey is the first all-Galaxy measurement of the SED's of sources in star forming regions, allowing estimation of density and temperature gradients of a very large sample of young cores. In our dedicated observing program, a survey of Chamaeleon dark cloud was carried out using slow-scanning modes of AKARI/IRC, since the mode realizes her sensitivities reaching the faint level of photosphere of the main-sequence stars, and also remains wide coverage of the sky to find any orphan young stars in the region. The time scale in the proto-planetary disk must be determined by the quantitative samples pretty directly. The result of the Chamaeleon survey will be focused on in the talk. Lifetime of the interplanetary dust under the Poynting-Robertson drag is much shorter than the age of the Solar System, which leads that some supply sources must exist in the present Solar System, as well as the Vega-like stars. The birth of Infrared Astronomical Satellite (IRAS) dramatically changed then smooth featureless picture of the zodiacal dust cloud by revealing numerous bands of asteroidal debris, several narrow trails of cometary dust, and a clumpy dust ring just outside the Earth's circumsolar orbit. The IRAS has thus renamed the used to be featureless zodiacal cloud as interplanetary dust cloud complex. However, due to sparse coverage of solar elongation angle, the IRAS data alone may not tell us much about the intermediate scale structures in the visible zodiacal light. In the beginning of 1990s the COBE/DIRBE mapped almost entire sky with a 0.7 arc-degree size beam and with established calibration. One of the most exciting results of the DIRBE/COBE mission is a full confirmation of the mean motion resonance(MMR) of the dust ring, and an isolation of the leading and trailing blobs in the MMR feature. The AKARI mission's coverage of the solar elongation angle is limited to very narrow span from 89.5 to 91.5 arc-degree, however the AKARI mission is proud of its superbly high sensitivity and commands its sharp vision of fine spatial resolution. Furthermore, its wavelength coverage is ideally tuned for studying local IPDs and the IPD cloud as well. Topics on the large scale mapping of the IDP cloud, and spectroscopy of the zodiacal emission will be discussed in the talk. I will also introduce a current status of two missions; PLANET-C and EXCEED (former name was TOPS) briefly at the end of my talk. |