Star Formation in the Cometary Tails Associated with Cluster Galaxies

TL;DR

This study explores star formation in the cometary tails of cluster galaxies, focusing on molecular cloud evolution and the role of magnetic fields in star formation processes within stripped gas tails.

Contribution

It provides new insights into the state of gas in galaxy tails, suggesting molecular clouds form in tails and magnetic fields are crucial for cloud survival and star formation.

Findings

Gas tails are mainly stripped as HI or diffuse molecular gas, not as molecular clouds.

Molecular clouds condense in tails even far from the host galaxy.

Magnetic fields may suppress Kelvin-Helmholtz instability, aiding cloud survival.

Abstract

We investigate the star-formation in cometary tails of galaxies in clusters. In particular, we focus on the evolution of molecular clouds in the tails that generate the stars. Assuming that the gas tails had been derived from the galaxies through ram-pressure stripping, we found that the gas must have been stripped mostly not in the form of molecular clouds, but in the form of HI gas or molecular gas that is not in clouds. Moreover, the molecular clouds are condensed in the tails even away from the host galaxies. We also found that magnetic fields may be required to suppress Kelvin-Helmholtz (KH) instability on the surface of molecular clouds, because otherwise KH instability may destroy the molecular clouds before stars are formed in them.