1. Gas of Planck Cold Dust Clumps
Yuefang Wu
Astronomy Department,Peking University
Team: Tie Liu, Fanyi Meng, Huawei Zahng, Jinghua Yuan
Ping Chen, Runjie Hu, Taiwei Zhang
Collaborators: Di Li, Sheng Li Qin, Bingang Ju, Karl Menten
Christian Henkel , Arnaud Belloche, Xin Guan

2. Outline 1. Planck early results and follow-up studies
2. Our observations:
CO survey
Dense molecular line observation
3. General properties
4. Mapping results
5. Future work

3. 1. Early results of Planck Satellite
ECC Sources
10783 ~14 K
Mass: 1-10^5M⊙
915 most reliable
Follow up studies
Various equipment:
Herschel PMO 13.7m
100, Molecular lines
250, 350μm
Still continuum Key for
Dynamics

4. 2. Our observations CO Surveys 2011-12
J=1-0 of CO, 13CO，C18O: PMO, 13.7m, 56”
Receiver： Nine beam SIS array
Velocity resolution: 12CO: 0.16 km/s 13CO, C18O: 0.17 km/s
rms: 12CO, 0.2 K : 13CO, C18O : 0.1 K
Single point: on/off
Mapping： OTF More than 600 CO cores were obtained
Dense molecular lines: --under progress
J=1-0 of HCO+, HCN, N2H PMO
IRAM map, 3’x3’, Apr. 30-May 5, 24 sources were mapped
Several cores were observed with 2-1 of CO, 13CO，C18O at CSO
Publication:
Wu et al +12, ApJ 756, 123; Liu, Wu Meng 2012, ApJS 202, 4;
Meng, Wu, Liu 2013, ApJS 209, 7; Liu, Wu, Zhang 2013, ApJL, 775,L2

5. 3. General properties: CO results
All were observed, but 39 of the cores have reference position problem
All were detected with 12CO and 13CO, 68% for C18O
Double and more components were identified, 108 additional components were obtained for 12CO J=1-0
10% 13CO J=1-0 emission <3σ
50% C18O J=1-0 emission <3σ :

6. 1). Line center velocity; distance
Basic parameter
Histogram: Normal distribution
V12-V13; V13-V18
Correlation:
V12 vs. V13 V13 vs. V18
100%
Velocity difference of molecular lines
is very common
In the 6 NH3 cores of IRDC G084.81−01.09:
Vlsr(CO)-Vlsr(13CO)
(Zhang et al. 2011)
All are > 1 km/s

7. •D: range 0.1 – 22 kpc • 82% < 2 kpc • 51%: 0.5 –1.5 kpc
The agreement was revealed for the first time
Initial conditions of star formation
- less dynamic layer of the molecular regions
System velocity: 13CO line
more optical thin that CO,
more common than C18O
V13 center velocity- system velocity
A basic application kinematic D
D from IRDCs (Simon et al. 2006)
most are on Galactic plane
•D: range 0.1 – 22 kpc
• 82% < 2 kpc
• 51%: 0.5 –1.5 kpc

8. 2). Physical parameters and line profile
Excitation temperature: Derived from T12
Assuming 12CO optical thick
If the system is LTE, then kinematic temperature Tk obtained
Range: –27 K wider than that of Td: K
Higher part:
12 with Tk > 17 K,
all are located in Orion and Tauri
Lower part: additional components
dust emission are not resolved yet
Property of distribution:
deviated from lognormal
distribution is small

9. Line widths: Observed FWHM:
Most of the cores with narrow lines
A criterion: 1.5 km/s for High-mass and Low-mass cores
(Myers et al. 2083; Wu et al. 2003; Wang et al. 2009)
H: 162; the remain belong to L.
Thermal and non-thermal velocity dispersion:
as well as σ3D were investigated
Property of the distribution:

10. Column density NH2 :
NH2 and the related optical depth tau13
derived from T13 with radiation transfer equation
assuming 13CO line optical thin
NH2 spans from 1020 to 4.5x1022 cm-3 , much larger than that of the nearby cores (Myers et al. 1983)
Distribution:
K-S test: Both are lognomal distribution + power larw tail

11. Line profiles:
15 cores: center dip, absorption at the line center, rather symmetric
Blue asymmetric, Red asymmetric ,40
Blue profile, 15 (Nb) --2% Red profile, 5 (Nr) %
small
blue excess: E= (Nb-Nr)/Nt = (Nt=782) very small
IRAM observation of HMPs and UCHII: 0.17 and 0.58 respectively
(Wu et al. 2007)
But blue profiles > red profiles, implying more cores are going to collapse than the protostellar objects driving mass outward

13. Velocity dispersions:
With R:
All, highest at 5 kpc
dynamic process is most
violent at 5 kpc ring
from 6 kpc, linearly increase
turbulence becomes more
strong in the out part
of the Galaxy
With Z:
All decrease with Z
from the disk to Z= pc
High again at ~680 pc minor peak
related with Orion, Tauri
Revealed for the first time

14. High latitude: 41 higher than 250
the highest 710 , previous 440
5: belong to group H
NH2: 3x1021 cm-2 , average,
σNT smaller among the 12 regions
regions but larger than that in
Oph, Oph-Sgr, Tex: intermediate
3 BA: G Z: 930 pc
G pc
G pc
3 RA: G pc
G pc
G was mapped
Surveys: 16o≤b ≤ 44o,117o≤l ≤ 160o 13% CO detected(Heithausen ea 1993)
-30o—(-43o) : 110 clouds not dense enough to form stars (Yamamoto ea 2003
 Planck cores are more closer to SF status

15. 3). CO abundance and depletion Liu, Wu, Zhang 2013
correlates with
Td,L/M
anti-correlates with β
Depletion:
Correlates with β
anti-correlates with

16. 4). Evolutional states of the cores
Comparison for cumulative of FWHM of 13CO lines and NH2 of
5 different star formation samples
FWHM: Methanol maser source have the largest FWHM
Planck cores the smallest
NH2: Column density: Planck cores the smallest too

17. 4. Mapping results Search CO cores: CO mapping: Data were divided
into Regions
according to
Dame et al. (1987)
All the regions:
~630 cores
Example: Orion
Liu, Wu Zhang, 2012
Grey:Hª Red:CO (Dame )
Blue: 100μm
Green: Planck clumps

18. 51 clumps
82 cores

19. Example:
Taurus:
Meng, Wu, Liu
2013
Dots:
Planck clumps
Colour: Vlsr

20. Taurus: Meng, Wu, Liu, 2013
71 Clumps
38 cores

21. 1). Dense cores: Single point observed with 1-0 of HCO+
1). Dense cores: Single point observed with 1-0 of HCO+. HCN 170 were detected with HCO+ and 120, HCN So far 24 were mapped with (1-0) of HCO+, HCN and N2H+ using IRAM Some of the cores have been observed with CSO too

22. HCO+ (1-0) and HCN (1-0)

23. Mapping with IRAM and CSO

25. 13CO 2-1 13CO 1-0 counters 12CO 1-0 Grey scale C18O 2-1
Black filled star: YSO
13CO 2-1

26. Checked with infrared data: Wise W1-W4 wavelength bands
104/170 were starless candidates
Examples:
3.4, 4.6 and 12 μm, 22 μm
-- Without protostellar mid-infrared counterparts

29. 2). Diffuse clouds: Most with stellar sources; star less N≤ 1020 cm-2

30. Evolution routing: ISMmolecular cloudsISM
Four-steps:
Starless diffuse Diffuse with sources
(ISM to molecular cloud) (Masers, YSOs, …)
FAST HI emission
FAST HI absorption
Starless core Cores with sources
(Cores form within cloud) (star-forming phase)

31. 5. Future work: Surveys with CO 1-0 and 3 mm lines: HI observation:
Complete the 1-0 of CO, 13CO and C18O with PMO I, I, III, Cep
Dense molecular lines: N2H+, D2H+ (1-0) HC3N, HC5N, SiO
NH3
Southern hemisphere, MOPRA, in preparing
HI observation:
It is on going by Prof. Li
Prepare for FAST
High resolution continuum observation
JCMT SCUBA2 : Legacy project organized by Tie Liu
High frequency line observation
ESO project organized by Ke Wang was approved

32. Thank You!