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PHYSICAL AND CHEMICAL STRUCTURE OF HIGH MASS
STAR FORMING REGIONS
I.I. Zinchenko
Institute of Applied Physics of the Russian Academy of Sciences
46 Uljanov str., Nizhny Novgorod 603950, Russia
zin@appl.sci­nnov.ru
In recent years we surveyed several tens of high mass star forming regions in various molec­
ular lines and in millimeter wave continuum. Basic physical properties of detected clumps
and molecular abundances were derived. One of the problems is a selection of the best tracer
of mass distribution. In particular, we found that in regions of high mass star formation
the CS emission correlates well with the dust continuum emission and is therefore a good
tracer of the total mass while the N 2 H + distribution is frequently very di#erent. This is
opposite to their typical behavior in low­mass cores where a freeze­out plays a crucial role in
the chemistry. The behavior of other high density tracers varies from source to source but
most of them are closer to CS. Radial density profiles in massive cores are fitted by power
laws with indices about -1.6, as derived from the dust continuum emission. The radial
temperature dependence on intermediate scales is close to the theoretically expected one
for a centrally heated optically thin cloud. The velocity dispersion either remains constant
or decreases from the core center to the edge. Several cores including those without known
embedded IR sources show signs of infall motions. They can represent the earliest phases
of massive protostars. There are implicit arguments in favor of small­scale clumpiness in
the cores.
Acknowledgements. The work was supported by the Russian Foundation for Basic Re­
search grant 06­02­16317 and by the Program ``Extended objects in the Universe'' of the
Russian Academy of Sciences.