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J/A+A/600/A141      Orion A integral shaped filament image  (Kainulainen+, 2017)

Resolving the fragmentation of high line-mass filaments with ALMA: the integral shaped filament in Orion A. Kainulainen J., Stutz A.M., Stanke T., Abreu-Vicente J., Beuther H., Henning T., Johnston K.G., Megeath S.T. <Astron. Astrophys. 600, A141 (2017)> =2017A&A...600A.141K (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Radio continuum ; Millimetric/submm sources Keywords: ISM: clouds - ISM: structure - stars: formation - ISM: individual objects: OMC-2 - radio continuum: ISM Abstract: We study the fragmentation of the nearest high line-mass filament, the integral shaped filament (ISF, line-mass ∼400M/pc) in the Orion A molecular cloud. We have observed a 1.6pc long section of the ISF with the Atacama Large Millimetre/submillimeter Array (ALMA) at 3mm continuum emission, at a resolution of ∼3" (1200AU). We identify from the region 43 dense cores with masses about a solar mass. 60% of the ALMA cores are protostellar and 40% are starless. The nearest neighbour separations of the cores do not show a preferred fragmentation scale; the frequency of short separations increases down to 1200AU. We apply a two-point correlation analysis on the dense core separations and show that the ALMA cores are significantly grouped at separations below ∼17000AU and strongly grouped below ∼6000AU. The protostellar and starless cores are grouped differently: only the starless cores group strongly below ∼6000AU. In addition, the spatial distribution of the cores indicates periodic grouping of the cores into groups of ∼30000AU in size, separated by ∼50000AU. The groups coincide with dust column density peaks detected by Herschel. These results show hierarchical, two-mode fragmentation in which the maternal filament periodically fragments into groups of dense cores. Critically, our results indicate that the fragmentation models for lower line-mass filaments (∼16M/pc) fail to capture the observed properties of the ISF. We also find that the protostars identified with Spitzer and Herschel in the ISF are grouped at separations below ∼17000AU. In contrast, young stars with disks do not show significant grouping. This suggests that the grouping of dense cores is partially retained over the protostar lifetime, but not over the lifetime of stars with disks. This is in agreement with a scenario where protostars are ejected from the maternal filament by the slingshot mechanism, a model recently proposed for the ISF. The separation distributions of the dense cores and protostars may also provide an evolutionary tracer of filament fragmentation. Description: We used the ALMA interferometer during Cycle 2 to observe the northern part of the ISF at 3mm continuum emission and C18O line emission (ESO Project ID 2013.1.01114.S, PI Kainulainen). In this paper we only use the continuum emission data. Both the 12-m and the 7-m (Atacama Compact Array; ACA) arrays were employed. The 7-m array observations were conducted on 16th August 2014 and the 12-m array observations in a compact configuration on 16th January 2015. Objects: ----------------------------------------- RA (2000) DE Designation(s) ----------------------------------------- 05 35 17.3 -05 23 28 Orion A = M 42 ----------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 147 1 Information on FITS image isf-3mm.fits 2880 2230 FITS image
See also: J/ApJ/566/974 : CHANDRA obs. of YSOs in OMC-2 and OMC-3 (Tsujimoto+, 2002) J/AJ/125/1537 : QUIRC Chandra sources in OMC 2/3 (Tsujimoto+, 2003) J/ApJ/716/893 : Polarisation at 850mu{m} in OMC-2 and OMC-3 (Poidevin+, 2010) J/A+A/556/A57 : Transitions in OMC-2 FIR 4 in the far-IR (Kama+, 2013) J/A+A/588/A30 : Properties of cores in OMC 2/3 (Sadavoy+, 2016) J/A+A/596/A26 : OMC-2 FIR 3 and FIR 4 [OI] maps (Gonzalez-Garcia+, 2016) 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- 27 I4 --- Ny Number of pixels along Y-axis 29- 51 A23 --- Obs.Date Observation date (YYYY-MM-DDThh:mm:ss.sss) 53- 59 F7.3 GHz Freq Observed frequency 61- 64 I4 Kibyte size Size of FITS file 66- 77 A12 --- FileName Name of FITS file 79-147 A69 --- Title Title of the FITS file
Acknowledgements: Jouni Kainulainen, jtkainul(at)mpia.de
(End) Patricia Vannier [CDS] 26-Apr-2017
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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