J/A+A/545/A51   1.4mm and 3mm interferometry of IRAS 19410+2336   (Rodon+, 2012)

Fragmentation in the massive star-forming region IRAS 19410+2336. Rodon J.A., Beuther H., Schilke P. <Astron. Astrophys. 545, A51 (2012)> =2012A&A...545A..51R 2012A&A...545A..51R
ADC_Keywords: Interstellar medium; Interferometry; Radio continuum; Radio lines Keywords: stars: formation - instrumentation: high angular resolution - instrumentation: interferometers - ISM: individual objects: IRAS 19410+2336 Abstract: The core mass functions (CMFs) of low-mass star-forming regions are found to resemble the shape of the initial mass function (IMF). A similar result is observed for the dust clumps in high-mass star-forming regions, although on spatial scales of clusters that do not resolve the substructure that is found in these massive clumps. The region IRAS 19410+2336 is one exception, having been observed on spatial scales on the order of ∼2500AU, which are sufficient to resolve the clump substructure into individual cores. We investigate the protostellar content of IRAS 19410+2336 at high spatial resolution at 1.4mm, determining the temperature structure of the region and deriving its CMF. The massive star-forming region IRAS 19410+2336 was mapped with the PdBI (BCD configurations) at 1.4mm and 3mm in the continuum and several transitions of formaldehyde (H2CO) and methyl cyanide (CH3CN). The H2CO transitions were also observed with the IRAM 30m Telescope. We detect 26 continuum sources at 1.4mm with a spatial resolution as low as ∼2200AU, several of them with counterparts at near-infrared and mid-infrared wavelengths, distributed in two (proto)clusters. With the PdBI CH3CN and PdBI/IRAM 30m H2CO emission, we derive the temperature structure of the region, ranging from 35K to 90K. Using these temperatures, we calculate the core masses of the detected sources, ranging from ∼0.7M to ∼8M. These masses are strongly affected by the spatial filtering of the interferometer, which removes a common envelope with ∼90% of the single- dish flux. Considering only the detected dense cores and accounting for binning effects as well as cumulative distributions, we derive a CMF, with a power-law index b≃2.3±0.2. We resolve the Jeans length of the (proto)clusters by one order of magnitude, and only find a small velocity dispersion between the different subsources. Since we cannot unambiguously differentiate between protostellar and prestellar cores, the derived CMF is not prestellar. Furthermore, because of the large fraction of missing flux, we cannot establish a firm link between the CMF and the IMF. This implies that future high-mass CMF studies will need to complement the interferometer continuum data with the short spacing information, a task suitable for ALMA. We note that the method of extracting temperatures using H2CO lines becomes less applicable when reaching the dense core scales of the interferometric observations because most of the H2CO appears to originate in the envelope structure. Description: 10 fits files, respectively containing: maps of continuum flux at 110GHz and 218GHz for the northern and southern clusters; cubes of H2CO(30,3-20,2), H2CO(32,2-22,1), and the CH3CN(6k-5k) with k=0-3, also for the northern and southern clusters. These data correspond to Figures 1, 3, 4, 5, 6, and 8 of the paper. Objects: ------------------------------------------------------------------- RA (2000) DE Designation(s) ------------------------------------------------------------------- 19 43 10.70 +23 44 58.40 IRAS 19410+2336 North = IRAS 19410+2336 19 43 11.20 +23 44 03.20 IRAS 19410+2336 South = IRAS 19410+2336 ------------------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file maps.dat 117 10 Maps list fits/* . 10 Fits files -------------------------------------------------------------------------------- See also: J/ApJ/566/945 : Massive star forming regions at 1.2mm (Beuther+, 2002) J/A+A/466/1065 : submm images of IRAS 05358+3543 (Beuther+, 2007) J/A+A/474/911 : 1.3mm and CO(2-1) maps of IRAS 20343+4129 (Palau+, 2007) J/A+A/475/925 : IRAS 05358+3543 (sub)mm maps (Leurini+, 2007) J/A+A/490/213 : 1.4 and 3.4mm interferometry of W3 IRS5 (Rodon+, 2008) J/A+A/510/A5 : CO(2-1) maps of IRAS 00117+6412 (Palau+, 2010) J/A+A/543/A88 : NGC7538IRS1 and NGC7538S 1.36mm maps (Beuther+, 2012) Byte-by-byte Description of file: maps.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 22 A22 --- FileName Name of the file in subdirectory fits 24- 32 F9.5 deg RAdeg Right ascension of field center (J2000) 33- 41 F9.5 deg DEdeg Declination of field center (J2000) 43-136 A94 --- Title Title and characteristics of the file -------------------------------------------------------------------------------- Acknowledgements: Javier A. Rodon, jrodon(at)eso.org References: Beuther & Schilke, 2004Sci...303.1167B 2004Sci...303.1167B, Fragmentation in massive star formation
(End) Javier A. Rodon [ESO, Santiago, Chile], Patricia Vannier [CDS] 27-Jul-2012
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