J/A+A/610/A77 Orion Integral Filament ALMA+IRAM30m N2H+(1-0) data (Hacar+, 2018)
An ALMA study of the Orion Integral Filament.
I. Evidence for narrow fibers in a massive cloud.
Hacar A., Tafalla M., Forbrich J., Alves J., Meingast S., Grossschedl J.,
Teixeira P.S.
<Astron. Astrophys. 610, A77 (2018)>
=2018A&A...610A..77H 2018A&A...610A..77H (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds ; Clusters, galaxy
Keywords: ISM: clouds - ISM: kinematics and dynamics - ISM: structure -
stars: formation - submillimeter: ISM
Abstract:
We have investigated the gas organization within the paradigmatic
Integral Shape Filament (ISF) in Orion in order to decipher whether or
not all filaments are bundles of fibers.
We combined two new ALMA Cycle 3 mosaics with previous IRAM 30m
observations to produce a high-dynamic range N2H+ (1-0) emission map
of the ISF tracing its high-density material and velocity structure
down to scales of 0.009pc (or ∼2000AU).
From the analysis of the gas kinematics, we identify a total of 55
dense fibers in the central region of the ISF. Independently of their
location in the cloud, these fibers are characterized by transonic
internal motions, lengths of ∼0.15pc, and masses per unit length
close to those expected in hydrostatic equilibrium. The ISF fibers are
spatially organized forming a dense bundle with multiple hub-like
associations likely shaped by the local gravitational potential.
Within this complex network, the ISF fibers show a compact radial
emission profile with a median FWHM of 0.035pc systematically narrower
than the previously proposed universal 0.1pc filament width.
Our ALMA observations reveal complex bundles of fibers in the ISF,
suggesting strong similarities between the internal substructure of
this massive filament and previously studied lower-mass objects. The
fibers show identical dynamic properties in both low- and high-mass
regions, and their widespread detection in nearby clouds suggests a
preferred organizational mechanism of gas in which the physical fiber
dimensions (width and length) are self-regulated depending on their
intrinsic gas density. Combining these results with previous works in
Musca, Taurus, and Perseus, we identify a systematic increase of the
surface density of fibers as a function of the total mass
per-unit-length in filamentary clouds. Based on this empirical
correlation, we propose a unified star-formation scenario where the
observed differences between low- and high-mass clouds, and the origin
of clusters, emerge naturally from the initial concentration of
fibers.
Description:
Combined ALMA+IRAM30m large-scale N2H+(1-0) emission in the Orion ISF.
Two datasets are presented here in FITS format:
1.- Full data cube: spectral resolution = 0.1 kms-1
2.- Total integrated line intensity (moment 0) map
Units are in Jy/beam
See also: https://sites.google.com/site/orion4dproject/home
Objects:
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RA (2000) DE Designation(s)
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05 35 14.0 -05 22 24 Integral Shape Filament (ISF)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 164 2 List of fits files
fits/* . 2 Individual fits files
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See also:
J/A+A/600/A141 : Orion A integral shaped filament image (Kainulainen+, 2017)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 32 I3 --- Nz ? Number of slices for the datacube
34- 59 A26 --- Obs.Date Observation date (YYYY-MM-DDThh:mm:ss.ssssss)
61- 66 I6 m/s bRV ? Lower value of radial velocity interval
for the datacube
68- 72 I5 m/s BRV ? Upper value of radial velocity interval
for the datacube
74- 76 I3 m/s dRV ? Radial velocity resolution for the datacube
78- 84 F7.4 GHz Freq ? Observed frequency for the image
86- 91 I6 Kibyte size Size of FITS file
93-104 A12 --- FileName Name of FITS file, in subdirectory fits
106-164 A59 --- Title Title of the FITS file
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Acknowledgements:
Alvaro Hacar, hacar(at)strw.leidenuniv.nl
(End) Alvaro Hacar [Leiden obs, NL], Patricia Vannier [CDS] 23-Jan-2018