Fragmentation in the Massive Star-Forming Region IRAS 19410+2336

TL;DR

This study maps the core mass function in the high-mass star-forming region IRAS 19410+2336 at high resolution, revealing a CMF similar to the IMF but limited by missing flux and spatial filtering.

Contribution

First high-resolution interferometric analysis of the CMF in IRAS 19410+2336, highlighting the impact of spatial filtering and the need for combined data for accurate IMF comparison.

Findings

Detected 26 continuum sources in two protoclusters

Derived a CMF with a power-law index of -2.3±0.2

Identified limitations due to missing flux and envelope contamination

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 at spatial scales of clusters that do not resolve the substructure found in them. The region IRAS 19410+2336 is one exception, having been observed at spatial scales on the order of ~2500AU, resolving the clump substructure into individual cores. We mapped that region with the PdBI in the 1.4mm and 3mm continuum and several transitions of H2CO and CH3CN. The H2CO transitions were also observed with the IRAM 30m Telescope. We detected 26 continuum sources at 1.4mm with a spatial resolution down to ~2200 AU, distributed in two protoclusters. With the lines emission we derived the temperature structure of the region, ranging from 35 to 90K. With them we calculated the core masses of the detected sources, ranging from ~0.7 to ~8 M_sun. These masses were strongly (~90%) affected by the interferometer spatial filtering. Considering only the detected dense cores we derived a CMF with a power-law index b=-2.3+-0.2. We resolve the Jeans length of the protoclusters by one order of magnitude, and only find little velocity dispersion between the different subsources. Since we cannot unambiguously differentiate protostellar and prestellar cores, the derived CMF is not prestellar. Also, because of the large 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 data, 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.