Norikazu Mizuno (Nagoya University)

New Views of Molecular Gas Distribution of the Southern Sky: COSurveys with NANTEN - Norikazu Mizuno Colloquium

ATNF Marsfield Lecture Theatre

Abstract

I will present a current status of the molecular-cloud survey in the
southern sky conducted by Nagoya University with the NANTEN 4m
millimeter-submillimeter wave telescope. The NANTEN telescope is
installed at the Las Campanas Observatory in Chile. Since 1996, we
have carried out surveying molecular clouds, mainly in the J=1-0
transitions of the CO isotopes of 12CO, 13CO, and C18O at a beam size
of 2.7 arcmin toward more than a million points. One of our key
projects, the Galactic-plane survey in 12CO, has almost covered 60
deg > l > 240 deg, |b| < 10 deg with grid spacings of 4 arcmin for
|b| < 5 deg and of 8 arcmin for the rest. This survey succeeded to
reveal the CO distribution in the Galactic plane with higher spatial
resolution and sensitivity than the Colombia survey, and resulted in
a number of detections of candidates for supershells. We have also
covered entire molecular-cloud complexes in major SFRs such as Orion,
Chamaeleon and Aquila-Ophiuchus-Lupus, which lead to dense-core
surveys. These resulted in finding of molecular clouds and cloud
cores with wide ranges of mass, size, and density in various
circumstances.
A CO survey for the Magellanic Clouds has also been completed
with NANTEN. This survey has revealed the first complete sample of
giant molecular clouds(GMCs) in these galaxies at a linear resolution
of ~ 40 pc. The GMCs exhibit a good spatial correlation with youngest
stellar clusters often associated with the giant HII regions. The ages
of clusters associated with GMCs are fairly young, < 10 Myr,
demonstrating that cluster formation is on-going in these GMCs.
I will also mention the future plan of NANTEN telescope, move to
the Atacama (ALMA) site, upgrade for the sub-millimeter waveband.