Igor ZinchenkoInstitute of Applied Physics,

Russian Academy of Sciences

Stan Kurtz – Centro de Radioastronomía y Astrofísica de la UNAM, Mexico

Sheng-Yuan Liu, Yu-Nung Su – Academia Sinica Institute of Astronomy and Astrophysics, Taiwan

Rui-Qing Mao – Purple Mountain Observatory CAS, China

Devendra Ojha – Tata Institute of Fundamental Research, India

Detailed studies of the structure and physical properties of high mass star forming regions on various scales.

Investigation of star formation triggering by expansion of H II regions.

Studies of chemical variations in high mass star forming regions on various scales.

A part of theA part of the S 255N spectrum measured at S 255N spectrum measured at SMASMA

S255IR S255N

MSX 8 MSX 8 μμmm + + GB6GB6 CO J=1-0CO J=1-0(observed at PMO-(observed at PMO-14m)14m)

1313CO(1-0) (color) and MSX 8 µm CO(1-0) (color) and MSX 8 µm contourscontours

43 10 M

10pc

M

L

CO and CO and 1313CO spectra in the central “hole”CO spectra in the central “hole”

The envelope should be clumpy and The envelope should be clumpy and turbulentturbulent

VLA 3 cm (green) and HCOVLA 3 cm (green) and HCO++(4-3) (blue) contours (4-3) (blue) contours overlaid on the Spitzer 3.6 and 8 overlaid on the Spitzer 3.6 and 8 μμm imagesm images

1.2 mm (IRAM-30m) contours (log scale) 1.2 mm (IRAM-30m) contours (log scale) overlaid on the Spitzer 8 overlaid on the Spitzer 8 μμm imagem image

An example of sequential high mass star An example of sequential high mass star formation?formation?

MM1MM1 MM2MM2 MM3MM3

Mass (solar Mass (solar masses)masses)

~ 85~ 85 ~ 30~ 30 ~ 55~ 55

Size (pc)Size (pc) < 0.03< 0.03 < 0.03< 0.03 ~ 0.06~ 0.06

∆∆V (km/s)V (km/s) ~ 3~ 3 ~ 3~ 3 ~ 2~ 2

MMvir vir (solar (solar masses)masses)

< 50< 50 < 50< 50 ~ 30~ 30

n (cmn (cm-3-3)) > 6 10> 6 1077 > 2 10> 2 1077 ~ 3 10~ 3 1066

1.2 mm

SMA images of S255IR in various lines

CH3CN spectrum towards S255 IR mm1 and the best fit

S255IR: 1.1 mm continuum (color), 20 cm continuum (green S255IR: 1.1 mm continuum (color), 20 cm continuum (green contours) and CO line wings (blue and red contours).contours) and CO line wings (blue and red contours).

The position-velocity diagram for the CO outflow

S255N: 1.1 mm continuum (color), 20 cm continuum (green S255N: 1.1 mm continuum (color), 20 cm continuum (green contours), 1.3 cm continuum (blue contours) and NHcontours), 1.3 cm continuum (blue contours) and NH33 (1,1) (1,1) emission (yellow contours)emission (yellow contours)..

How common is triggering?How common is triggering?

Star formation in envelopes of H II regions is a common phenomenon and is probably triggered by expansion of these envelopes.

Observations of different CO isotopes indicate that the envelopes are clumpy and turbulent.

In the regions of active star formation clumps at various stages of this process are observed. Physical properties and chemical content of these clumps can differ significantly.

Highly collimated bipolar outflows and disks in regions of high mass star formation imply the star formation process similar to that for low mass stars.