Constraining the ages of the fireballs in the wake of the dIrr galaxy VCC1217 / IC3418

TL;DR

This study uses multiwavelength data to analyze star-forming blobs around galaxy VCC1217/IC3418, concluding they formed within the last 400 million years due to ram pressure stripping by the Virgo cluster.

Contribution

It provides new age constraints for the blobs and links their formation to recent environmental interactions with the Virgo cluster.

Findings

Blobs formed within the last 400 Myr.

Ram pressure stripping is the likely formation mechanism.

Galaxy shows signs of recent gas depletion.

Abstract

A complex of Halpha emitting blobs with strong FUV excess is associated to the dIrr galaxy VCC1217 / IC3418 (Hester et al. 2010), and extends up to 17 Kpc in the South-East direction. These outstanding features can be morphologically divided into diffuse filaments and compact knots, where most of the star formation activity traced by Halpha takes place. We investigate the properties of the galaxy and the blobs using a multiwavelength approach in order to constrain their origin. We collect publicly available data in UV and Halpha and observe the scene in the optical U,g,r,i bands with LBT. The photometric data allows to evaluate the star formation rate and to perform a SED fitting separately of the galaxy and the blobs in order to constrain their stellar population age. Moreover we analyze the color and luminosity profile of the galaxy and its spectrum to investigate its recent interaction with the Virgo cluster. Our analysis confirms that the most plausible mechanism for the formation of the blobs is ram pressure stripping by the Virgo cluster IGM. The galaxy colors, luminosity profile and SED are consistent with a sudden gas depletion in the last few hundred Myr. The SED fitting of the blobs constrains their ages in < 400 Myr.