Infall in massive clumps harboring bright infrared sources

TL;DR

This study observes massive clumps with bright infrared sources, detecting infall signatures indicative of global collapse, and finds that infall rates correlate with clump mass and luminosity, highlighting gravity's role in star formation.

Contribution

It provides new observational evidence of infall in massive clumps and quantifies infall velocities and rates using CO lines, linking these to clump properties.

Findings

18 out of 30 clumps show blue infall profiles

Mass infall rates range from 10^{-3} to 10^{-1} M_sun/yr

Higher luminosity correlates with larger infall rates

Abstract

Thirty massive clumps associated with bright infrared sources were observed to detect the infall signatures and characterize infall properties in the envelope of the massive clumps by APEX telescope in CO(4-3) and C$^{17}$O(3-2) lines. Eighteen objects have "blue profile" in CO(4-3) line with virial parameters less than 2, suggesting that global collapse is taking place in these massive clumps. The CO(4-3) lines were fitted by the two-layer model in order to obtain infall velocities and mass infall rates. Derived mass infall rates are from 10$^{-3}$ to 10$^{-1}$ M$_{\odot}$yr$^{-1}$. A positive relationship between clump mass and infall rate appears to indicate that gravity plays a dominant role in the collapsing process. Higher luminosity clump has larger mass infall rate, implying that the clump with higher mass infall rate has higher star formation rate.