Evidence of Core Growth in the Dragon Infrared Dark Cloud: A Path for Massive Star Formation

TL;DR

This study provides evidence that cores in the Dragon infrared dark cloud grow in mass after their formation, which influences theories on how massive stars originate from smaller initial cores.

Contribution

It presents the first statistical evidence of core mass growth in an infrared dark cloud, challenging the idea that massive stars form from initially massive cores.

Findings

Protostellar cores are more massive than starless cores.

Core mass growth occurs after initial formation.

Implications for massive star formation theories.

Abstract

A sample of 1.3 mm continuum cores in the Dragon infrared dark cloud (also known as G28.37+0.07 or G28.34+0.06) is analyzed statistically. Based on their association with molecular outflows, the sample is divided into protostellar and starless cores. Statistical tests suggest that the protostellar cores are more massive than the starless cores, even after temperature and opacity biases are accounted for. We suggest that the mass difference indicates core mass growth since their formation. The mass growth implies that massive star formation may not have to start with massive prestellar cores, depending on the core mass growth rate. Its impact on the relation between core mass function and stellar initial mass function is to be further explored.