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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 (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: Objects: ------------------------------------------------------- RA (2000) DE Designation(s) ------------------------------------------------------- 05 35 14.0 -05 22 24 Integral Shape Filament (ISF) ------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 164 2 List of fits files fits/* 0 2 Individual fits files
See also: J/A+A/600/A141 : Orion A integral shaped filament image (Kainulainen+, 2017) 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- 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
Acknowledgements: Alvaro Hacar, hacar(at)
(End) Alvaro Hacar [Leiden obs, NL], Patricia Vannier [CDS] 23-Jan-2018
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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