ROCKETS I: Investigating the Impact of the Rocket Effect on Two Nearby Young Open Clusters Encased in Infrared Bubbles
Abstract
We introduce ROCKETS (Rocket-driven Cluster Kinematics & Triggered Star-formation), a Gaia based programme investigating kinematic fingerprints of stellar feedback or rocket effect in young star forming regions. We analyse two young clusters with O-type stars enclosed by mid-infrared bubbles, Collinder 69 and IC 1396 as a methodological demonstration on two nearby benchmark regions. Co-moving candidates are selected within an astrometric ellipse defined by the median and median absolute deviation of Class I/II YSOs with Gaia data. For each star, we compute a relative proper-motion angle (RPMA) relative to the ionising source. In both regions the RPMA distribution shows a strong excess at RPMA <15∘, corresponding to sources moving away from the respective ionising sources. We quantify this using the Rocket Effect Index (REI), finding REI≃ 1.1 for Collinder 69 and REI≃ 1.7 for IC 1396. When considering only Class I/II YSOs, the REI of both regions increases to REI≳ 10. Velocity-structure analysis of the sample shows that the RPMA <15∘ subset has stronger positive pairwise expansion than the full co-moving population, providing additional support for the rocket effect. The outward-moving stars are not uniformly distributed; instead, their position angles are strongly anisotropic and preferentially aligned towards the bright-rimmed clouds. Gaia colour-magnitude diagrams show no strong age offset between sources moving outward and literature cluster members. The observed kinematic signatures support feedback-driven acceleration of gas and triggered star formation preferentially towards higher density regions of expanding bubbles due to the rocket effect.
Related
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BibTeX
@misc{arun2026rockets,
title = {{ROCKETS I: Investigating the Impact of the Rocket Effect on Two Nearby Young Open Clusters Encased in Infrared Bubbles}},
author = {R. Arun and G. Maheswar and Annapurni Subramaniam and Piyali Saha and T. P. Sudheesh and B. Shridharan and Blesson Mathew and Akhil Krishna R},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.05272},
eprint = {2609.05272},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.05272},
}
RIS
TY - UNPB
TI - ROCKETS I: Investigating the Impact of the Rocket Effect on Two Nearby Young Open Clusters Encased in Infrared Bubbles
AU - R. Arun
AU - G. Maheswar
AU - Annapurni Subramaniam
AU - Piyali Saha
AU - T. P. Sudheesh
AU - B. Shridharan
AU - Blesson Mathew
AU - Akhil Krishna R
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2609.05272
UR - https://arxiv.org/abs/2609.05272
AB - We introduce ROCKETS (Rocket-driven Cluster Kinematics & Triggered Star-formation), a Gaia based programme investigating kinematic fingerprints of stellar feedback or rocket effect in young star forming regions. We analyse two young clusters with O-type stars enclosed by mid-infrared bubbles, Collinder 69 and IC 1396 as a methodological demonstration on two nearby benchmark regions. Co-moving candidates are selected within an astrometric ellipse defined by the median and median absolute deviation of Class I/II YSOs with Gaia data. For each star, we compute a relative proper-motion angle (RPMA) relative to the ionising source. In both regions the RPMA distribution shows a strong excess at RPMA <15^∘, corresponding to sources moving away from the respective ionising sources. We quantify this using the Rocket Effect Index (REI), finding REI≃ 1.1 for Collinder 69 and REI≃ 1.7 for IC 1396. When considering only Class I/II YSOs, the REI of both regions increases to REI≳ 10. Velocity-structure analysis of the sample shows that the RPMA <15^∘ subset has stronger positive pairwise expansion than the full co-moving population, providing additional support for the rocket effect. The outward-moving stars are not uniformly distributed; instead, their position angles are strongly anisotropic and preferentially aligned towards the bright-rimmed clouds. Gaia colour-magnitude diagrams show no strong age offset between sources moving outward and literature cluster members. The observed kinematic signatures support feedback-driven acceleration of gas and triggered star formation preferentially towards higher density regions of expanding bubbles due to the rocket effect.
ER -