Molecular cloud and star formation

Yuefang Wu

Star formation group Astronomy Department

Peking University

Outline Progress obtained in the past: 1. Gas heating and motion in molecular clouds: (1). Energetic of Molecular clouds—remain problem (2). Motions and distribution of molecular species 2. Core and their property 3. High velocity molecular outflows 4. Collapse of star formation region 5. Triggering of star formation This year: New subject: ISM and initial states of star

forming Future Work: Confidence for the Millimeter Astronomy of our country Planck cores of all the sky Massive star formation

Progress obtained

Beginning Thanks are given to Prof. Shou-Guan Wang introduced to us “Astrophysics of interstellar molecules” by Prof. G. Winnewisser of Cologne Univ. 1n 1979 Owing to: Efforts of teachers and students Collaborating with domestic and abroad colleagues Progresses were obtained during the past ~30 years: 1. Molecular clouds: (1). Energetic of Molecular clouds—remain problem Energetic of molecular cloud-last 70’ Problem remained: 8 clouds were not agreed wit the standard picture Our work demonstrated: dust=gas couple well except 1-2 persist: possible reasons Wu & Evans, 1989; Wu et al. 1990

(2). Motions and distribution of molecular species Nearby dark cores thermal motion dominates them according to previously NH3 studies We test it with emission of more heaver molecular specie CS Result I: Line widths of heavier molecule > those of light ones Result II. Emission regions of heavier molecule > those of light ones

--- two puzzles

Non–thermal dynamical processes dominate these cores There is chemical differentiation Onion model of molecular cloud is ideal situation Zhou, Wu et al. 1989; Wu 1992

2. Core and their property Surveys for cores: UC HII candidates IRAS colour indexes 1-0 of CO 13CO C18O Extremely young stellar objects: Own indexes CO2-1, 3-2 Water masers with weak IRAS NH3 (1,1) (2,2) (3,3) (4,4) Massive cores: guided by Methanol masers 1-0 of CO 13CO

C18O 350 regions were searched 180 cores with different evolutional phases were obtained Anatomy of cores: example: G28.34+0.06:

Wu et al. 2001 Wang, Wu et al. 2009

Liu, Wu, Ju 2010 Ren, Wu, Liu et al. 2012

- Physical properties: Dynamical processes; Evolutional statesWe also made detailed investigation for typical cores:

Wu et al. 2006 Wang et al. 207

Hierarchical fragmentation High collimated bipolar outflows exist in high mass star forming regions

too

Wang et al. 2007 Wang et al. 2012

3. High velocity molecular outflows: Molecular outflows searched and identified: Both single dishes, interferometers used Water maser: searched; time variation HH object driving sources identified: new method Up-dated study was made for 25 years1 • Inclination Angle -- derived from observation • Common of in high mass star formation too 39% of 391 are high mass ones • Demonstrate the indirect correlation

Lbol ------- mass accretion rates --------- outflow mass -------- mass loss rate -----

• Demonstrate non-radiation stellar driving.

Wu et al. 2005

Inclination angle: KOSMA Kong & Wu 2011

logM=-1.04 +/- 0.08+(0.56 +/- 0.02)logLbollogM=-1.04 +/- 0.08+(0.56 +/- 0.02)logLbolr = 0.78r = 0.78 R=0.73

Wu et al. 2004 Wu et al. 2005

R=0.72

4. Collapse of high mass star formation regions: The question for high mass star formation: Radiation halts the mass for Msun>8 YSOsSeek and search for collapse signatures: Obtained three results for which no similar report was seen before: (1). Mapped Core JCMT 18354-0649S:

We found this core at Effelsberg 100 m, followed up study with JCMT, the referee point out it was a leading sample and suggested its name - 4 evidences for collapse the strongest signature is at the center associated with outflow

Wu, Zhu, Wei et al. 2005

We also studied this core with SMA:

Follow up studies were also done by Zhu et al. 2011

Liu et al2011

Carolan et al. (2009) made more line observations and 3D modell analyse, quoted our results 9 times and used the data that we observed

(2) Carried a mapping survey: Using IRAM two groups of different evolutional samples were surveyed with multiple lines: I: UCHII precursors II: UCHII regions

Blue excess: E group II > E of group I:

Wu et al. 2007

Inflow motion in different evolutional phases:

Sources Evolutionary phases----------------------------------------------------------------------------------------------------- High mass Earlier than PUCHII PUCHII UC HII

examples ISOSS, Core JCMT G34.26 (total >70) E HCO+(1-0) … … 17% 58% (this work)

15%a 53% (CO 4-3)b HCO+(3-2) -0.04e

----------------------------------------------------------------------------------------------------

W3-SE– PUCHII

CARMA+IRAMZhu et al.. 2010

CARMA

G23.44-0.18- PUCHII

Ren et al. 2011

Liu et al. 2011

G9.62+0.19, SMA

Core F PUCHII Core E UCHII

Evolution time tendency-seems consistent with single dish results HMC HMPSOs UC HII Regions G9.62+0.19-F Core JCMT, W3-SE G19.6, N7538 Single dish Red profile blue profile blue profile interfero. Red deeper pro. blue deeper pro. inverse P Cygni profile

• The results seem to be consistent with the statistical increase of red profiles, or less “blue excess ” in HMPOs than in UC HII regions

New method of identification for collapse signature two lines one line with map

Wu et al. 2007

(3). G19.61-0.23 Inside-out evidence was obtained for the first time: R(CO) > R (CN)

Vin(CN)> Vin (CO)

inside out collapse by Shu et al. (1987)

Wu et al. 2009

5. Triiggering of star formation

S87—Cloud collision Collision and trigged cores First time using HCO+ lines measured at PMO 13.7 m Xue & Wu 2008

W75N and DR21—Cloud collision Velocity structure, and star formation activities Mao, Wu, Liu 2009 WR –HD211853: wind triggering Wind triggering (Liu, Wu, Zhang, Qin 2012)

S87:

W75N and DR21

WR

HD

21185

3

More recently, Planck early results were studied: C3PO: Cold Core Catalogue of Planck Objects: 10783 clumps ECC: the early Cold Core Catalogue : 915, most relable We surveyed 674 ECC cores using 13.7 m telescope of PMO

with J=1-0 lines of CO, 13CO and C18O (Wu, Liu, Meng, Li, Qin 2012) Revealed gas properties: For example: Cold: Tex: 4—37 K quiet:

Still non-thermal motion dominated::

Their Emission regions and mophologies

Mapping study was also made for Complex Orion (Liu, Wu, Zhang 2012) & Taurus (Meng, Wu, Liu

2012)

Evolutional states:

Among the 6 samples shown in the figure,

4 were our group’s.

Future Work

Confidence for the Millimeter Astronomy of our country

--the foundation and condition that is already present

• Science base, frontier subject • Team of talents prepared Continue to collaborate • Our own new equipment International advanced equipment

PMO 13.7 m

NRAO 12 mShanghai 25 m Xinjiang 25 m

Effelsberg 100 m KOSMA 3 m

Upper: IRAM JCMT CSO

Lower:GBT MOPRA

SMA

VLA/EVLA

Planck cores of all the sky: CO results show: 4 kinds of states: diffuse-YSOs core-YSOs Core+YSOs

dissuse+YSOs • Initial conditions; • IMF • cloud formation • cloud evolution Massive star formation: • Disk -- beginning from all the intermediate mass stars • collapse – evolution with time • Stimulating formation: feed back (burst, HII, WR)

Thank You!