IC 3418: Star Formation in a Turbulent Wake

TL;DR

This paper reports the discovery of a 17 kpc UV tail with ongoing star formation in galaxy IC 3418, likely caused by ram pressure stripping in the Virgo Cluster, and explores the mechanisms behind tail formation.

Contribution

It provides evidence that star formation occurs in molecular clouds formed in a turbulent stripped wake, offering insights into tail formation mechanisms during ram pressure stripping.

Findings

Star formation is ongoing in the tail of IC 3418.

The tail likely formed during ram pressure stripping, not tides.

Morphologies of tails reflect forces during formation.

Abstract

Galaxy Evolution Explorer observations of IC 3418, a low surface brightness galaxy in the Virgo Cluster, revealed a striking 17 kpc UV tail of bright knots and diffuse emission. H alpha imaging confirms that star formation is ongoing in the tail. IC 3418 was likely recently ram pressure stripped on its first pass through Virgo. We suggest that star formation is occurring in molecular clouds that formed in IC 3418's turbulent stripped wake. Tides and ram pressure stripping (RPS) of molecular clouds are both disfavored as tail formation mechanisms. The tail is similar to the few other observed star-forming tails, all of which likely formed during RPS. The tails' morphologies reflect the forces present during their formation and can be used to test for dynamical coupling between molecular and diffuse gas, thereby probing the origin of the star forming molecular gas.