Investigation of Rocket Effect in BRC 18 using Gaia EDR3

TL;DR

This study investigates the influence of the Rocket Effect on BRC 18 using Gaia EDR3 data, revealing that candidate YSOs are moving away from $\lambda$ Ori and showing no preferred disc orientation relative to magnetic fields.

Contribution

It provides new insights into the kinematic behavior of YSOs in BRC 18 and supports the presence of the Rocket Effect through proper motion analysis.

Findings

Candidate YSOs are moving away from $\\lambda$ Ori.

Discs are oriented randomly with respect to magnetic fields.

12 new young sources are identified as co-moving with YSOs.

Abstract

Bright-rimmed clouds (BRCs) are ideal candidates to study radiation-driven implosion mode of star formation as they are potential sites of triggered star formation, located at the edges of H{\sc ii} regions, showing evidence of ongoing star formation processes. BRC 18 is located towards the eastern edge of relatively closer ($\sim$400 pc) H{\sc ii} region excited by $\lambda$ Ori. We made R-band polarimetric observations of 17 candidate young stellar objects (YSOs) located towards BRC 18 to investigate any preferred orientation of the discs with respect to the ambient magnetic field and the direction of energetic photons from $\lambda$ Ori. We found that the discs are oriented randomly with respect to the projected magnetic field. Using distances and proper motions from the \textit{Gaia} EDR3 of the candidate YSOs, we investigated the possible acceleration of BRC 18, away from $\lambda$ Ori due to the well known "Rocket Effect", by assuming that both the candidate YSOs and BRC 18 are kinematically coupled. The relative proper motions of the candidate YSOs are found to show a trend of moving away from $\lambda$ Ori. We computed the offset between the angle of the direction of the ionization front and the relative proper motion of the candidate YSOs and found it to lie close to being parallel to each other. Additionally, we found 12 sources that are comoving with the known candidate YSOs towards BRC 18. These comoving sources are most likely to be young and are missed in previous surveys conducted to identify potential YSOs of the region.