The Astrophysical Journal, 780:119 (20pp), 2014 January 10 doi:10.1088/0004-637X/780/2/119 C 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A. TRANSFORMATION OF A VIRGO CLUSTER DWARF IRREGULAR GALAXY BY RAM PRESSURE STRIPPING: IC3418 AND ITS FIREBALLS Jeffrey D. P. Kenney1, Marla Geha1, Pavel Jachym´ 1,2,HughH.Crowl3, William Dague1, Aeree Chung4, Jacqueline van Gorkom5, and Bernd Vollmer6 1 Yale University Astronomy Department, P.O. Box 208101, New Haven, CT 06520-8101, USA;
[email protected] 2 Astronomical Institute, Academy of Science of the Czech Republic, Bocni II 1401, 141 00 Prague, Czech Republic 3 Bennington College, Bennington, VT, USA 4 Department of Astronomy and Yonsei University Observatory, Yonsei University, 120-749 Seoul, Korea 5 Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027, USA 6 CDS, Observatoire astronomique de Strasbourg, UMR7550, 11 rue de l’universite,´ F-67000 Strasbourg, France Received 2013 August 1; accepted 2013 November 18; published 2013 December 16 ABSTRACT We present optical imaging and spectroscopy and H i imaging of the Virgo Cluster galaxy IC 3418, which is likely a “smoking gun” example of the transformation of a dwarf irregular into a dwarf elliptical galaxy by ram pressure stripping. IC 3418 has a spectacular 17 kpc length UV-bright tail comprised of knots, head–tail, and linear stellar features. The only Hα emission arises from a few H ii regions in the tail, the brightest of which are at the heads of head–tail UV sources whose tails point toward the galaxy (“fireballs”).