Investigation of Rocket Effect in Bright-Rimmed Clouds using Gaia EDR3

TL;DR

This study uses Gaia EDR3 data to analyze the motion of young stars in bright-rimmed clouds, providing strong evidence for the radiation-driven 'Rocket Effect' causing these clouds and stars to move away from ionizing sources.

Contribution

It demonstrates the prevalence of the Rocket Effect in multiple BRCs using Gaia proper motions, expanding previous findings from BRC 18 to a larger sample.

Findings

Candidate YSOs tend to move away from ionizing sources.

Strong correlation between proper motion angles and directions to ionizing sources.

Most BRCs show motion consistent with the Rocket Effect.

Abstract

Bright-rimmed clouds (BRCs) are excellent laboratories to explore the radiation-driven implosion mode of star formation because they show evidence of triggered star formation. In our previous study, BRC 18 has been found to accelerate away from the direction of the ionizing Hii region because of the well known "Rocket Effect". Based on the assumption that both BRC 18 and the candidate young stellar objects (YSOs) are kinematically coupled and using the latest Gaia EDR3 measurements, we found that the relative proper motions of the candidate YSOs exhibit a tendency of moving away from the ionizing source. Using BRC 18 as a prototype, we made our further analysis for 21 more BRCs, a majority of which showed a similar trend. For most of the BRCs, the median angle of the relative proper motion of the candidate YSOs is similar to the angle of on-sky direction from the ionizing source to the central IRAS source of the BRC. Based on Pearson's and Spearman's correlation coefficients, we found a strong correlation between these two angles, which is further supported by the Kolmogorov-Smirnov (K-S) test on them. The strong correlation between these two angles supports the "Rocket Effect" in the BRCs on the plane-of-sky.