J/A+A/690/A375 EMERGE III. Fiber networks in Orion (Socci+, 2024)
Emergence of high-mass stars in complex fibers networks (EMERGE).
III. Fiber networks in Orion.
Socci A., Hacar A., Bonanomi F., Tafalla M., Suri S.
<Astron. Astrophys. 690, A375 (2024)>
=2024A&A...690A.375S 2024A&A...690A.375S (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Radio sources
Keywords: molecular data - instrumentation: interferometers - ISM: clouds -
ISM: kinematics and dynamics - ISM: molecules - ISM: structure
Abstract:
Over the past decade, Herschel far-infrared (FIR) observations have
demonstrated the complex organisation characterising the interstellar
medium as networks of parsec-scale filaments. At the same time, fiber
networks have been found to aptly describe the gas structures in
star-forming regions at sub-parsec scales.
We aim to investigate the dense gas organisation prior to the
formation of stars in a selected sample of regions within Orion. We
surveyed seven prototypical star-forming regions in Orion as part of
the EMERGE Early ALMA Survey. Our sample includes low- (OMC-4 South,
NGC 2023), intermediate- (OMC-2, OMC-3, LDN 1641N), and high-mass
(OMC-1, Flame Nebula) star-forming regions all surveyed at a high
spatial resolution of 4.5 arcsec (or ∼2000au) in N2H+ (1-0). We used
a dedicated series of ALMA+IRAM-30m observations of this homogeneous
sample to systematically investigate the spatial distribution,
density, and thermal structure of the star-forming gas, along with its
column density variations and its internal motions in a wide range of
environments.
From the analysis of the gas kinematics, we identified and
characterised a total of 152 velocity-coherent fibers. The statistical
significance of our sample, the largest of its kind so far, highlights
these small-scale filamentary sub-structures as the preferred
organisational unit for the dense gas in low-, intermediate-, and
high-mass star-forming regions alike. Despite the varied complexity of
these sub-parsec networks (in terms of the surface density of their
constituent fibers), the masses and lengths of these objects show
similar distributions and consistent median values, as well as
(trans-)sonic motions, for all of our targets. The comparison between
the fiber line masses and virial line masses suggests that the
majority of these objects are sub-virial. Those fibers closer to the
virial condition, however, are also associated with a greater number
of protostars. Finally, the surface density of fibers is linearly
correlated with the total dense gas mass throughout by roughly one
order of magnitude in terms of both of these parameters. While most
fibers show comparable mass, length, and internal motions in our
survey, massive fibers that are close to the virial condition are
shown to be intimately connected to star formation. The majority of
the protostars in our target regions are, in fact, associated with
these objects.
The additional correlation between the surface density of fibers and
the dense gas mass in our survey demonstrates how the physical
properties of fibers can explain the current degree of star formation
in their host region. Our findings suggest a common mechanism for star
formation from low- to high-mass star-forming regions, mediated
through the formation and evolution of fiber networks.
Description:
The table fibers.dat contains the physical properties of the 152
fibers identified in the EMERGE Early ALMA Survey. x0 and y0 represent
the mean coordinates of each fiber as offset from the centre of the
map, given below for each Object. All the other properties are derived
from the analysis with HIFIVe + FilChap and are discussed in length
throughout the EMERGE III & IV papers.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------
05 35 20 -05 15 00 OMC-1
05 35 20 -05 15 00 OMC-2
05 35 22.5 -05 02 00 OMC-3
05 35 07.5 -05 55 00 OMC-4 South
05 36 27 -06 25 00 LDN 1641N
05 41 29 -02 20 20 NGC 2023
05 41 46 -01 56 37 Flame Nebula
-----------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
fibers.dat 387 152 Fibers physical properties
list.dat 224 7 List of fits datacubes
fits/* . 7 Individual fits datacubes
--------------------------------------------------------------------------------
See also:
https://doi.org/10.5281/zenodo.13628881 : link to the same table in Zenodo
https://emerge.univie.ac.at/results/data/ : link to the N2H+ (1-0) cubes (DR2)
Byte-by-byte Description of file: fibers.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Source Host region (1)
14- 34 F21.16 arcsec x0 Offset in x from the map centre
36- 55 F20.15 arcsec y0 Offset in y from the map centre
57- 74 F18.16 km/s dV Spectral linewidth
76- 93 F18.16 km/s e_dV Uncertainty on the linewidth
95-112 F18.16 --- sNT Mach number
114-131 F18.16 --- e_sNT Uncertainty on the Mach number
133-151 F19.16 km/s Vlsr Centroid velocity
153-170 F18.16 km/s e_Vlsr Uncertainty on the centroid velocity
172-190 F19.16 Msun Mass Total fiber mass
192-195 I4 --- points Number of components associated to the fiber
197-214 F18.15 K Tk Mean kinetic temperature of the fiber
216-233 F18.16 pc L Fiber length
235-254 F20.17 --- AR ? Aspect ratio
256-274 F19.16 km/s/pc gradVx Velocity gradient over the whole axis
276-294 F19.15 Msun/pc ML Line mass of the fiber
296-314 F19.16 km/s/pc lgrad Velocity gradient per axis knot
316-318 F3.1 --- P Number of protostars associated to the fiber
320-340 F21.18 pc FWHM ? Fiber width
342-363 E22.17 cm-2 N0 ? Column density at the fiber peak
365-384 F20.15 K/pc gradT ? Temperature gradient from the fiber
peak outwards
386-387 I2 --- ID [1/46] Identifier given to the fiber
by HiFIVe
--------------------------------------------------------------------------------
Note (1): Source names in the file are OMC1 (OMC-1), OMC2 (OMC-2), OMC3 (OMC-3),
OMC4 (OMC-4 South), LDN1641N (LDN 1641N), NGC2023 (NGC 2023),
Flame_Nebula (Flame Nebula)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 30 I3 --- Nz Number of pixels along Z-axis
32- 57 A26 "datime" Obs.date Observation date
59- 64 I6 m/s bVRAD Lower value of VRAd interval
66- 70 I5 m/s BVRAD Upper value of VRAd interval
72- 74 I3 m/s dVRAD VRAd resolution
76- 81 I6 Kibyte size Size of FITS file
83-167 A85 --- FileName Name of FITS file, in subdirectory fits
169-224 A56 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Andrea Socci, andrea.socci [at] univie.ac.at
References:
Hacar et al., Paper I 2024A&A...687A.140H 2024A&A...687A.140H
Bonanomi et al., Paper II 2024A&A...688A..30B 2024A&A...688A..30B
(End) Patricia Vannier [CDS] 24-Sep-2024