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Article overview
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Investigating the structure and fragmentation of a highly filamentary IRDC | J. D. Henshaw
; P. Caselli
; F. Fontani
; I. Jimenez-Serra
; J. C. Tan
; S. N. Longmore
; J. E. Pineda
; R. J. Parker
; A. T. Barnes
; | Date: |
25 Jul 2016 | Abstract: | We present 3.7 arcsec (~0.05 pc) resolution 3.2 mm dust continuum
observations from the IRAM PdBI, with the aim of studying the structure and
fragmentation of the filamentary Infrared Dark Cloud G035.39-00.33. The
continuum emission is segmented into a series of 13 quasi-regularly spaced
(~0.18pc) cores, following the major axis of the IRDC. We compare the spatial
distribution of the cores with that predicted by theoretical work describing
the fragmentation of hydrodynamic fluid cylinders, finding a significant
(factor of ~8) discrepancy between the two. Our observations are consistent
with the picture emerging from kinematic studies of molecular clouds suggesting
that the cores are harboured within a complex network of independent
sub-filaments. This result emphasises the importance of considering the
underlying physical structure, and potentially, dynamically important magnetic
fields, in any fragmentation analysis. The identified cores exhibit a range in
(peak) beam-averaged column density ($3.6{
m x}10^{23}{
m
cm}^{-2}<N_{H,c}<8.0{
m x}10^{23}{
m cm}^{-2}$), mass
($8.1M_{odot}<M_{c}<26.1M_{odot}$), and number density ($6.1{
m x}10^{5}{
m
cm}^{-3}<n_{H, c, eq}<14.7{
m x}10^{5}{
m cm}^{-3}$). Two of these cores,
dark in the mid-infrared, centrally-concentrated, monolithic (with no traceable
substructure at our PdBI resolution), and with estimated masses of the order
~20-25$M_{odot}$, are good candidates for the progenitors of
intermediate-to-high-mass stars. Virial parameters span a range
$0.2<alpha_{
m vir}<1.3$. Without additional support, possibly from
dynamically important magnetic fields with strengths of the order
230$mu$G<B<670$mu$G, the cores are susceptible to gravitational collapse.
These results may imply a multi-layered fragmentation process, which
incorporates the formation of sub-filaments, embedded cores, and the
possibility of further fragmentation. | Source: | arXiv, 1607.7452 | Services: | Forum | Review | PDF | Favorites |
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