Unveiling a Network of
Parallel Filaments in
the IRDC G14.225-0.506
Gemma Busquet (ICE, CSIC-IEEC)
Q. Zhang, A. Palau, J.M. Girart, A. Sánchez-Monge, R. Estalella, H.B. Liu,
F.P. Santos, G.A.P. Franco, T. Pillai, F. Wyrowski, I. de Gregorio-Monsalvo, P.T.P. Ho
From clouds to protoplanetary disks: the astrochemical link
Berlin, 5th October 2015
M17 complex
Discovery of an extended (77x16 pc) and
massive (>105 M⦿) molecular cloud
southwest of the HII region M17
(Elmegreen & Lada 1976)
CO(1-0)
evolution
Elmegreen & Lada 1976
distance ~1,98 kpc (Xu et al. 2011)
M17 complex
Discovery of an extended (77x16 pc) and
massive (>105 M⦿) molecular cloud
southwest of the HII region M17
(Elmegreen & Lada 1976)
distance ~1,98 kpc (Xu et al. 2011)
Spitzer image (Povich et al. 2009, Povich & Whitney 2010)
The IRDC G14.225-0.506 (M17 SWex)
Povich & Whitney (2010)
Several intermediate-mass YSOs identified using Spitzer data (Povich & Whitney 2010): Stage 0/I,
Stage II, Stage III, ambiguous
H2O maser emission (Wang et al. 2006)
IRAS 18153-1651: L~1.1x104 L⦿ and IRAS 18152-1658: L~3200 L⦿
The observational project
Dust continuum emission at 870 µm with
APEX-LABOCA and at 350 µm with the CSOSHARC II
CSO
APEX
Dense gas: NH3 (1,1) and (2,2) with the VLA
and Effelsberg 100 m (Busquet et al. 2013)
Molecular line survey at 3 mm with the
IRAM 30 m telescope (Busquet et al. in
prep.)
Polarimetric data: optical (R-band) and NIR
(H-band) using the 1.6 m telescope from the
Pico Dos Dias Observatory; and 350 µm
polarized emission with CSO-SHARP
(Santos et al. in prep., Busquet et al. in prep.)
Effelsberg
VLA
IRAM 30m
OPD
The large scale view of the cloud: NH3
Busquet et al. (2013)
Extended and clumpy filamentary structure: network of 8 filaments and 2 hubs
Filaments appear parallel in projection in two preferred directions at PA=10°, 60°
The large scale view of the cloud: NH3
Hub-N
Hub-S
F10-C/W
The large scale view of the cloud: NH3
Velocity dispersion locally enhanced toward hubs,
while all filaments appear more quiescent
Presence of two velocity components in regions
where filaments intersect hubs
Physical properties
HUBS
FILAMENTS
FWHM (pc)
0.23
0.12
Aspect Ratio
5:1
15:1
Trot (K)
15
11
𝛔TOT (km/s)
1.0
0.5
Mline (M⦿ pc-1)
400
130
Hubs appear more compact, warmer, and show larger 𝛔 and larger Mline
Cores within filaments have separations λobs ~0.33 pc, which is consistent with
the fragmentation of an isothermal cylinder due to “sausage”-type instability
λf ~0.16-0.21 pc using cs
λf ~0.4-0.8 pc using 𝛔TOT
The IRAM 30m survey at 3mm
preliminary results
The IRAM 30m survey
OBSERVATIONS:
OTF maps to cover the whole cloud of 9’x13’
E90 + FTS200: velocity resolution ~0.7 km/s
Frequency range: 86.81 - 94.59 GHz / 102.49 - 110.27 GHz
Rms ~ 40 mK
28 molecular transitions detected arising from 18 species, with Eup~4.2 - 30 K
OVERVIEW:
Cloud: C18O, C2H, HCN, HNC, HCO+
Dense filaments: N2H+, HC3N
Shock tracers: SiO, CH3OH, CH3CN
Only associated with hub-N: SO, SO2, HNCO
The cloud
HCO+ (1-0)
HCN (1-0)
optically thick and extended emission
A zoo of line profiles
HCO+ (1-0)
wings, multiple
components,
self-absorption
The cloud
C18O (1-0)
HNC (1-0)
Dense filaments
velocity field NH3(1,1)
velocity field N2H+ (1-0)
Busquet et al. (2013)
Two main velocity components: vLSR~18.3-20.8 km/s and vLSR~20.8-23.2 km/s
Dense filaments
N2H+ (1-0)
line width
Line broadening usually associated with the presence of two components
Dense filaments: NH- and dust
N2H+ (1-0)
Dense filaments: CN-molecules
HC3N (10-9)
HN13C (1-0)
Dense filaments: CN-molecules
HC3N (10-9)
HN13C (1-0)
CN- group of molecules brightest in filaments rather than in hubs
Dense filaments: CS-molecules
13CS
(2-1)
H2CS (30,3-20,2)
Dense filaments: CS-molecules
13CS
(2-1)
H2CS (30,3-20,2)
CS - group of molecules brightest toward hubs
Polarimetric survey
Optical (R-band in red) and near-IR (H-band yellow) polarization maps
Santos, Franco, Busquet et al. in preparation
Polarimetric survey
Optical (R-band in red) and near-IR (H-band yellow) polarization maps
foreground corrected maps
Santos, Franco, Busquet et al. in preparation
Polarimetric survey
Optical (R-band in red) and near-IR (H-band yellow) polarization maps
foreground corrected maps
Overall correlation between the large-scale magnetic field lines and the direction
perpendicular to the cloud
Santos, Franco, Busquet et al. in preparation
Polarized Emission
Filaments and Hubs are well
orientated perpendicularly to
magnetic field lines
Btot ~100-500 μG
Mass-to-magnetic flux
ratio 0.3-2.3
MA ~0.4 - 0.8 sub-alfvénic
conditions
Santos, Franco, Busquet et al. in preparation
Conclusions
High angular resolution observations reveal a network of filaments constituting
two hub-filament systems
Filaments appear parallel in projection and distributed along two preferred
directions at PA~10° and 60°
Within each filament the velocity variations are small
Network separated by two velocity components
Chemical differentiation within the cloud
B~100-500 μG, sub-alfvénic conditions, but does not prevent the gravitational
collapse of most filaments, which in general are supercritical.
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