J/ApJS/259/36 Filaments in the inner Galactic plane from ATLASGAL (Ge+, 2022)
A census of 163 large-scale (≥10pc), velocity-coherent filaments in the
inner Galactic plane: physical properties, dense-gas fraction, and association
with spiral arms.
Ge Y., Wang K.
<Astrophys. J. Suppl. Ser., 259, 36 (2022)>
=2022ApJS..259...36G 2022ApJS..259...36G
ADC_Keywords: Molecular clouds; Galactic plane; Interstellar medium
Keywords: Catalogs ; Interstellar filaments ; Galaxy structure ;
Star formation ; Interstellar clouds
Abstract:
The interstellar medium has a highly filamentary and hierarchical
structure that may play a significant role in star formation. A
systematical study of the large-scale filaments toward their physical
parameters, distribution, structures, and kinematics will inform us
about which types of filaments have the potential to form stars, how
the material feeds protostars through filaments, and the connection
between star formation and Galactic spiral arms. Unlike the
traditional by-eye searches, we use a customized minimum spanning tree
algorithm to identify filaments by linking Galactic clumps from the
APEX Telescope Large Area Survey of the Galaxy catalog. In the inner
Galactic plane (|l|<60°), we identify 163 large-scale filaments
with physical properties derived, including the dense-gas mass
fraction, and we compare them with an updated spiral arm model in
position-position-velocity space. The dense-gas mass fraction is found
not to differ significantly in various Galactic positions or in
different spiral arms. We also find that most filaments are interarm
filaments after adding a distance constraint, and filaments in arms
differ a little with those not in arms. One surprising result is that
clumps on and off filaments have no significant distinction in their
mass at the same size.
Description:
The filaments are identified from ATLASGAL
(Urquhart+ 2018, J/MNRAS/473/1059) clumps using the minimum spanning
tree (MST) method developed by Wang et al. (2016ApJS..226....9W 2016ApJS..226....9W).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 164 170 Physical properties of the identified
163 filaments and parameter statistics
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See also:
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/ApJ/723/1019 : Galactic SFR and gas surface densities (Heiderman+, 2010)
J/ApJ/723/492 : Physical data of GRS molecular clouds (Roman-Duval+, 2010)
J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010)
J/A+A/554/A55 : C18O(1-0) and N2H+(1-0) in L1495/B213 (Hacar+, 2013)
J/ApJS/209/2 : The BGPS. X. Dense molecular gas (Shirley+, 2013)
J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280<l<60 (Urquhart+, 2014)
J/ApJ/805/157 : BGPS. XIII. Mass functions (Ellsworth-Bowers+, 2015)
J/A+A/590/A131 : Giant molecular filaments in the MW (Abreu-Vicente+, 2016)
J/A+A/591/A5 : ATLASGAL dense filamentary structures (Li+, 2016)
J/A+A/600/A141 : Orion A integral shaped filament image (Kainulainen+, 2017)
J/MNRAS/477/298 : Young star clusters in nearby mol. clouds (Getman+, 2018)
J/A+A/610/A77 : Orion Integral Filament ALMA+IRAM N2H+(1-0) (Hacar+, 2018)
J/A+A/619/A166 : SEDIGISM, kinematics of ATLASGAL filaments (Mattern+, 2018)
J/MNRAS/473/1059 : Complete sample of Gal. clump properties (Urquhart+, 2018)
J/ApJ/885/131 : High-mass SFR plx & proper motion with VLBI (Reid+, 2019)
J/ApJ/886/102 : ALMA obs. of 70um dark high-mass clumps (Sanhueza+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Obj Row type (1)
6- 8 I3 --- ID [1/163]? Assigned filament ID
10- 15 F6.2 deg GLON [-1.9/354.64] Flux-weighted Galactic
longitude, lwt
17- 20 F4.2 deg e_GLON [0.01/0.4]? Uncertainty in GLON
22- 26 F5.2 deg GLAT [-1.3/2.2] Flux-weighted Galactic latitude,
bwt
28- 31 F4.2 deg e_GLAT [0.01/0.2]? Uncertainty in GLAT
33- 38 F6.1 km/s VLSR [-121/114] Flux weighted local standard of
rest (LSR) velocity, vwt
40- 42 F3.1 km/s e_VLSR [0.2/5]? Uncertainty in VLSR
44- 47 F4.1 kpc Dist [1.3/19.7] Distance, the median of all clump
distances in this filament
49- 51 I3 --- Ncl [5/169] The number of clumps in the filament
53- 57 F5.1 pc Lsum [4.4/370.2] Sum of "edges" (separation of
each two connected clumps) of filament
59- 63 F5.1 pc Lend [2.3/109.4] End-to-end length along the major
axis
65- 68 F4.2 km/s/pc Vgrad [0.06/1.75] Mean velocity gradient on edges
70- 73 F4.2 km/s/pc e_Vgrad [0.01/2.71]? Uncertainty in Vgrad
75- 78 F4.1 K Tmin [-0.5/22.1] Minimum temperature of clumps
80- 83 F4.1 K Tmax [0.8/53.0] Maximum temperature of clumps
85- 89 F5.1 10+3Msun Mass [1.7/525.0] Mass of the filament (2)
91- 96 F6.1 Msun/pc Mline [2.1/7324.3] Line mass, mass per unit length
98- 100 F3.1 10+22cm2 NH2 [0.7/6.5] H2 column density
102- 105 F4.1 10+3cm3 nH2 [0.6/21.4] H2 volume density
107- 111 F5.1 --- Lsumw [2.9/133.4] Ratio between sum of edge lengths
and width (3)
113- 117 F5.2 --- fA [2/26.81] Aspect ratio (4)
119- 123 F5.2 --- fL [1.51/11.36] Linearity (5)
125- 129 F5.1 pc Lwt [1.8/121] Linearity-weighted end-to-end length
131- 134 F4.1 kpc Rgc [0.2/11.6] Median of clump Galactocentric
radii for the filament
136- 140 F5.1 pc Z [-99/82] Height above Galactic mid-plane
142- 145 F4.1 pc e_Z [0.7/12.5]? Uncertainty in Z
147- 150 F4.1 deg theta [-1/89] Orientation angle between filament
and Galactic mid-plane (6)
152- 154 F3.1 deg e_theta [0.1/9.6]? Uncertainty in theta
156- 158 A3 --- Morph Morphology class (7)
160- 164 F5.2 --- DGMF [-0.5/0.62]? Dense gas mass fraction (8)
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Note (1): The first 163 rows are marked as type "fil" and contain filament
properties. The last seven rows contain parameter statistics, including
minimum, maximum, median, mean, standard deviation, skewness (S), and
kurtosis (K).
Note (2): Mass of the filament, derived from Herschel Hi-GAL column density
map (detailed in Sect. 2.4).
Note (3): The ratio between sum of edge lengths and width. The width is the
mean of clump diameters.
Note (4): Aspect ratio, the ratio of area between the circle enclosing the
filament and the concave hull (detailed in Appendix B.2). For an
approximately elliptical distribution, fA is very similar with the
aspect ratio of the ellipse.
Note (5): Linearity, the ratio between spread (standard deviation) of clumps
along major axis and spread along minor axis.
Note (6): Orientation angle between filaments major axes and Galactic
mid-plane in the projected sky (calculation of abs(θ) is from PCA,
detailed in Appendix B.1)
Note (7): Morphology class following Wang et al. (2015MNRAS.450.4043W 2015MNRAS.450.4043W):
L = represents linear straight L-shape;
C = bent C-shape;
S = quasi-sinusoidal shape;
X = crossing of multiple filaments;
H = head-tail or hub-filament system.
Note (8): Dense gas mass fraction, the ratio between dense gas mass and
total mass of the filament. It is illustrated in Sect. 3.3
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 14-Jun-2022