J/A+A/642/A87 Hub-filament candidates (Kumar+, 2020)
Unifying low and high mass star formation through density amplified
hubs of filaments. The highest mass stars (>100M☉) form only in hubs.
Kumar M.S.N., Palmeirim P., Arzoumanian D., Inutsuka S.
<Astron. Astrophys. 642, A87 (2020)>
=2020A&A...642A..87K 2020A&A...642A..87K (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds ; Star Forming Region
Keywords: star formation - ISM: genetal -
open clusters and associations: general - stars: massive - HII regions
Abstract:
Star formation takes place in giant molecular clouds, resulting in
mass-segregated young stellar clusters composed of Sun-like stars,
brown dwarves and massive O-type (50-100M☉) stars.
To identify candidate hub-filament systems (HFS) in the Milky-Way and
examine their role in the formation of the highest mass stars and star
clusters.
Filaments around ∼35000 HiGAL clumps that are detected using the
DisPerSE algorithm. Hub is defined as a junction of three or more
filaments. Column density maps were masked by the filament skeletons
and averaged for HFS and non-HFS samples to compute the radial profile
along the filaments into the clumps.
∼3700~(11%) are candidate HFS of which, ∼2150~(60%) are pre-stellar,
∼1400~(40%) are proto-stellar. All clumps with L>104L☉ and
L>105L☉ at distances respectively within 2kpc and 5kpc are
located in the hubs of HFS. The column-densities of hubs are found to
be enhanced by a factor of ∼2 (pre-stellar sources) up to ∼10
(proto-stellar sources).
All high-mass stars preferentially form in the density enhanced hubs
of HFS. This amplification can drive the observed longitudinal flows
along filaments providing further mass accretion. Radiation pressure
and feedback can escape into the inter-filamentary voids. We propose a
'filaments to clusters' unified paradigm for star formation, with the
following salient features: a) low-intermediate mass stars form in the
filaments slowly (106yr) and massive stars quickly (105yr) in the
hub, b) the initial mass function is the sum of stars continuously
created in the HFS with all massive stars formed in the hub, c)
Feedback dissipation and mass segregation arise naturally due to HFS
properties, and c) explain age spreads within bound clusters and
formation of isolated OB associations.
Description:
We used 250um maps, column density maps, and the clumps catalogue from
the Herschel Hi-GAL survey to search for filamentary structures and
hubs.
Catalog of Hub-filament Systems (HFS) from the Hi-GAL survey.
This catalog contains 3560 unsaturated target information only and
does not include the 144 saturated sources used for analysis in the
paper.
The columns are 1)a running index HFxxxxx, 2) Galactic longitude in
degrees, 3) Galactic latitude in degrees, 4) distance in pc, 5) nskel
= number of filamentary skeletons forming the HFS, 6) Nh2out is the
column density (background subtracted) in units of 10-23cm-2 of
the skeleton lying outside the source FWHM, 7) lenout in pc is the
total length of the skeletons outside the source FWHM, 8) Mfil =
filament mass (in 103M☉) computed using Nh2out, and 9)
linemass of the filaments in units of 103M_☉/pc, defined as
Mfil/Lenout.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 60 3559 Hub-filament candidates catalog
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See also:
J/A+A/607/A22 : Monoceros R2 filament hub FIR observations (Rayner+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- HFS HFS number (HFNNNNN)
9- 18 F10.6 deg GLON Galactic longitude
20- 28 F9.6 deg GLAT Galactic latitude
30- 33 F4.1 kpc Dist Distance
35 I1 --- Nskel Number of skeletons
37- 41 F5.1 10+23cm-2 NH2out Total Column density
43- 47 F5.1 pc Lenout Total length of skeletons
49- 54 F6.1 10+3Msun Mfil Total mass of the filaments
56- 60 F5.1 10+3Msun/pc Mline Filament line mass
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Acknowledgements:
M.S. Nanda Kumar, nanda(at)astro.up.pt
(End) Patricia Vannier [CDS] 07-Aug-2020