J/A+A/591/A5 ATLASGAL dense filamentary structures (Li+, 2016)
ATLASGAL: A Galaxy-wide sample of dense filamentary structures.
Li G.-X., Urquhart J.S., Leurini S., Csengeri T., Wyrowski F.,
Menten K.M., Schuller F.
<Astron. Astrophys. 591, A5 (2016)>
=2016A&A...591A...5L 2016A&A...591A...5L (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Interstellar medium ; Morphology
Keywords: stars: formation - surveys - submillimeter: ISM - catalogs
Abstract:
We study the properties of filamentary structures from the ATLASGAL
survey.
We use the DisPerSE algorithm to identify spatially coherent
structures located across the inner-Galaxy (300<l<60 and |b|<1.5).
We have determined distances, masses and physical sizes for 241 of the
filamentary structures. We find a median distance of 3.8kpc, a mean
mass of a few 103M☉, a mean length of ∼6pc and a
mass-to-length ratio of (M/L)∼200-2000M_sun/pc. We also find that
these filamentary structures are tightly correlated with the spiral
arms in longitude and velocity, and that their semi-major axis is
preferentially aligned parallel to the Galactic mid-plane and
therefore with the direction of large-scale Galactic magnetic field.
We find many examples where the dense filaments identified in ATLASGAL
are associated with larger scale filamentary structures (∼100pc), and
argue that this is likely to be common, and as such these may indicate
a connection between large-scale Galactic dynamics and star formation.
We have produced a large and Galaxy-wide catalogue of dense
filamentary structures that are representative of a particular size
and mass range not previously well studied in the literature. Analyses
of the properties and distribution of these filaments reveals that
they are correlated with the spiral arms and make a significant
contribution to star formation in the Galaxy. Massive star formation
is ongoing within ∼20% of the filaments and is strongly correlated
with the filaments with the largest mass-to- length ratios. The
luminosity of the embedded sources has a similar distribution to the
Galactic-wide samples of young massive stars and can therefore be
considered to be representative.
Description:
The ATLASGAL survey (Schuller et al., 2009A&A...504..415S 2009A&A...504..415S) covers
300°<l<60° and |b|<15°. It has a typical noise level of
50-70mJy/beam and is sensitive to gas with H2 column densities
exceeding ∼1022cm-2.
We aim to study filamentary structures in the ATLASGAL survey. This
has been achieved through two steps. First, we extract skeleton
representations of structures in the dust continuum emission maps with
the DisPerSE (Discrete Persistent Extractor; Sousbie,
2011MNRAS.414..350S 2011MNRAS.414..350S). Then, the extracted structures are classified,
and filamentary structures are identified.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 81 517 Catalogue of ATLASGAL structures extracted by
DisPerSE and identified as filaments by visual
inspection of the emission maps
table3.dat 110 279 Physical properties of the 279 ATLASGAL
filaments for which a velocity has been
determined
refs.dat 68 28 References
list.dat 163 1812 List of images of all the 1812 structures
identified
fits_24um/* . 1812 Fits cutouts made from the 24um data in the
MIPSGAL (Carey et al. 2005, BAAS, 37, 1252)
survey, named Name_24um.fit
fits_i1/* . 1812 *Fits cutouts made from the 3.6um data in the
GLIMPSE survey, named Name_I1.fits
fits_i4/* . 1812 *Fits cutouts made from the 8um data in the
GLIMPSE survey, named Name_I4.fits
fits_atlasgal/* . 1812 Fits cutouts made from 870um data from the
ATLASGAL survey, named Name_atlasgal.fits
fits_skeleton/* . 1812 Fits cutouts of the skeleton of the structures
from this work, named Name_skeleton.fits
images/* . 1812 3 color composite images of all the detected
structures, named Name.eps
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Note on fits_i1/*, fits_i4/*: GLIMPSE survey (Benjamin et al.,
2003PASP..115..953B 2003PASP..115..953B, Cat. II/293; Churchwell et al. 2009PASP..121..213C 2009PASP..121..213C).
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See also:
J/A+A/540/A113 : Starless clumps in ATLASGAL (Tackenberg+, 2012)
J/A+A/544/A146 : ATLASGAL cold high-mass clumps with NH3 (Wienen+, 2012)
J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330<l<21 (Contreras+, 2013)
J/MNRAS/431/1752 : ATLASGAL 6.7GHz methanol masers (Urquhart+, 2013)
J/MNRAS/435/400 : ATLASGAL Properties of compact HII regions (Urquhart+, 2013)
J/MNRAS/443/1555 : ATLASGAL massive star forming clumps sample (Urquhart+ 2014)
J/A+A/565/A75 : ATLASGAL Dust condensations in Galactic plane
(Csengeri+, 2014)
J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280<l<60 (Urquhart+, 2014)
J/A+A/570/A65 : ATLASGAL massive clumps CO depletion (Giannetti+, 2014)
J/A+A/579/A91 : ATLASGAL inner Galaxy massive cold dust clumps
(Wienen+, 2015)
J/A+A/581/A74 : Molecular clouds as viewed by ATLASGAL (Abreu-Vicente+ 2015)
J/A+A/586/A149 : SiO in ATLASGAL-selected massive clumps (Csengeri+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Name (GLLL.lll+B.bbb) derived from Galactic
coordinates of the maximum intensity in
the structure
16 I1 --- Ag [1/6] Level of agreement (1)
18- 24 F7.3 deg GLON Galactic longitude
26- 30 F5.3 deg dGLON Angular extend in GLON
32- 37 F6.3 deg GLAT Galactic latitude
39- 43 F5.3 deg dGLAT Angular extend in GLAT
45- 48 F4.1 arcmin smaj Semi-major size
50- 52 F3.1 arcmin smin Semi-minor size
54- 57 F4.1 --- Aspect Aspect ratio
59- 63 F5.1 deg theta Position angle measured anti-clockwise from
Galactic mid-plane
65- 68 F4.1 arcsec Width Width estimated from the normalized intensity
distribution
70- 74 F5.1 Jy Sint Integrated 870um flux densities determined
from the flux of all pixels found within the
skeleton box
76- 78 I3 --- nPix Number of connecting pixels that form the
spine of the skeleton
80- 81 I2 --- nCSC ? Number of associated clumps identified in
the ATLASGAL CSC
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Note (1): Classification scheme as follows:
1 = Marginally resolved clumps: structures that appear as relatively isolated
structures with simple morphologies and small aspect ratios (<2).
We also use this classification for small groups of isolated clumps
that have no obvious connecting emission.
2 = Resolved elongated structures: structures classified in this group are
dominated by elongated structures with aspect ratios of 2-3 and a
relatively small number of associated spine points (<100pixels). These
may simply be unresolved filaments or fragments of larger filaments where
the connecting lower density gas does not have surveyscient column density
to have been detected by ATLASGAL. This class also includes unresolved
structures that are extended in more than two directions; these typically
consist of one or two central bright clumps associated with three of four
lower density strands protruding radially away from the centre.
3 = Filaments: elongated linear structures that are clearly resolved across
their lengths and widths and consisting of a single dominant filament with
relatively few sub-branches and typical aspect ratios larger than 3.
4 = Networks of filaments: several filaments that seem to be connected to each
other. In many cases these networks are coincident with similar networks
of infrared-dark clouds (IRDC) that are seen in absorption at mid-infrared
wavelengths against bright Galactic background emission.
5 = Complexes: they are regions of very bright extended and often complex
emission, and although DisPerSE has connected the emission together,
there is significant blending of the emission features. Consequently, the
derived parameters are unlikely to be reliable. Many structures that fall
into this category are already well-known complexes such as W43 and W49.
6 = Unclassified: this is a category for structures that cannot be classified
as any of the types described above. An example of a structure that is
included in this group is the Galactic centre region where the source
density is so high that the algorithm is unable to identify individual
structures and effectively groups all of the emission into a single
enormous structure. This category is therefore not considered a distinct
structure type and is excluded from further analysis.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Structure name
16- 21 F6.1 km/s Vlsr LSR velocity
23- 34 A12 --- r_Vlsr Reference(s) for Vlsr, in refs.dat file
35- 38 A4 --- n_Vlsr Note on Vlsr
40- 43 F4.1 kpc Dist ? Distance
45- 58 A14 --- r_Dist Reference(s) for Dist, in refs.dat file
59- 66 A8 --- n_Dist Note on Dist
68- 72 F5.2 pc Length ?=- Length
75- 78 F4.2 pc Width ?=- Width
81- 85 F5.3 [Msun] logMtot ?=- Total mass
87- 91 F5.2 [cm-2] logNH2m Mean H2 column density
93- 97 F5.2 [cm-2] logNH2p Peak H2 column density
99-100 I2 --- IRDC ? IRDC associated
102-110 A9 --- Bubble Bubble associated
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 46 A23 --- Aut Author's name
48- 68 A21 --- Com Comments
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Source name
17- 40 A24 --- 24um Name of the fits fimage at 24um
in subdirectory fits_24um
42- 63 A22 --- 3.6um Name of the fits image at 3.6um
in subdirectory fits_i1
65- 86 A22 --- 8.0um Name of the fits image at 8.0um
in subdirectory fits_i4
88-115 A28 --- atlasgal Name of the fits image at 670um
in subdirectory fits_atlasgal
117-144 A28 --- skeleton Name of the fits image skeleton
in subdirectory fits_skeleton
146-163 A18 --- image Name of the 3 color composite image
in subdirectory images
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Acknowledgements:
Guang-Xing Li, gxli(at)usm.lmu.de
(End) Patricia Vannier [CDS] 06-May-2016