Probing of massive star formation with dense molecular lines Infall Liu xunchuan (PKU) A observation Outflow FAST for the search Summary

Infall most molecular cloud is cold , thermal energy can't compete with gravity erergy，kinds of collapse models carried out inside-out (Frank su 1978) power law shaped density distribution with order 2 established from collapsing center to outer region outside-in (Larson) such distribution build from outer to inner region. two cores would established during collapse process. out forward velocity field may even established in some region.

Infall in high massive star forming radiation may stop accretion, upper limit on mass eg 40~100 Larson and Starrfield 1971,Kahn 1974,Yorke 1977...... Stellar more massive than 100 solar mass was found last 80s. accretion disk with bipolar jet , or merge?

Infall Blueprofile Unsysmetry MARDONES 1997 Infall velocity Myers 1996

A observation Blueprofile indicates inflow was detected very earily in low massive star , but detection in high massive star need higher space resolution,dense molecular probe and mapping observation. However, mapping observation is not fruitful. we had did a HCO+(1-0) mapping observation(PMO13.7m) of 24 sources. 32 cores are resolved and 8 ones show blueprofile and one show red profile.

A observation the left pictures show the one p oint emisson of HCO+(1-0) with black line and H13CO+(1-0) with red line, the right is contour maps of HCO+(1-0) emission. The black contour line mark the integrated intensity of HCO+(1-0) emission from 40 percent of maximal vaule to maximal vaule, step ed by 10 percent

A Observation Larson (1981) first carry out a power law relationship betewwn the core size and line with, with power 0.38. 0.31 for our sources.

A Observation blue Excess E = (Nblue- Nred)/Ntotal = 0.22。 our sample contain 7 UCHII region. work of APJ 667 L37 show blue excess for pre UCHII is 0.17, for UCHII is 0.58，so higher blueprofile decection rate is happened in later evolution stage for early cores. our result is predicable. Most core with infall show sign of outflow. for our sources the dynamical time scale of those outflow is 1E5 yesrs. But for poor resolution and sensitivity, it is dificult to pict out the morphology of outflow and its relationship with rotation disk if exist.

Outflow The formation and early resolution of high massive stars are poorly understood. Widely disparate formation models have been proposed, such as monolithic and competitive accretion; as well as coalescence. We are still not sure that if outflow of high massive stars are oriented perpendicular with the disk like the cases in low massive star G3141+0.31: The molecular outflow (mathonal 70-61) align with 7mm continuum component which was considered as a disk. E.Araya 2008

Outflow Cephes A 1.3 cm continuum (red contour) trace the inner region of the jet which is perpendicular to the disk traced by CH3CN J=18-17 . blue contour show 3 cm continuum. this may support that massive star forming through accretion. different wavelength continuum may show different mophologe of the outflow, and all are helpful for overall study of the circumstance and condition of outflow. Nimesh A 2005

FAST in searching high massive star FAST can provide a high sensitivity continuum image for the outflow of high massive stars.It can help us to understand the relationship between the disk and outflow. Neutarl wind (HI) were detected in low massive star forming region, and with FAST, we can also detect high velocity HI outflow in high massive stars formation region.

Summary infall and outflow in high massive star formation region is very important to understand the evolution of star forming with the help of FAST, we can study the outflow of star forming region more detaily, and extends the observation of it to wavelength ~1m