A study of H I-selected galaxies in the Hercules cluster

Jorge Iglesias-Páramo (1) , Willem van Driel (2, 3) , Pierre-Alain Duc (4) , Polychronis Papaderos (5) , Jose M. Vílchez (6) , Véronique Cayatte (2, 3) , Chantal Balkowski (2, 3) , K. O'Neil (7) , J. Dickey (8) , H. Hernández (7) , Trinh X. Thuan (9)

1 LAM - Laboratoire d'Astrophysique de Marseille
2 GEPI - Galaxies, Etoiles, Physique, Instrumentation
3 Physique des Galaxies et Cosmologie
4 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
5 Sternwarte Weinheim
6 IAA - Instituto de Astrofísica de Andalucía
7 Arecibo Observatory
8 Department of Astronomy, University of Minnesota
9 Astronomy Department, University of Virginia, Charlottesville

The present study focuses on a sample of 22 galaxies detected in the blind VLA H I survey of the Hercules cluster by Dickey (\cite{Dickey), 18 of which were selected on an H I line width smaller than 270 km s^-1 and 4 others with only tentative optical counterparts in the Palomar Sky Survey. Sensitive single-dish H I line spectra were obtained for 20 of them, and for one the VLA detection was not confirmed. Optical surface photometry has been carried out for 10 objects, for 8 of which optical spectroscopy was obtained as well. Based on various criteria, we classify two sample galaxies (ce-143 and ne-204) as genuine dwarfs whereas the remaining sample objects are found to be intrinsically luminous galaxies. For those objects investigated in optical wavelengths we determine properties similar to those of actively star-forming galaxies, and find that approximately one half of them has properties intermediate between those of dwarf galaxies and low-luminosity disc galaxies. No optical redshifts could be determined for two of the galaxies (sw-103 and sw-194) and their physical association with the H I clouds detected at their positions therefore remains uncertain. A particularly interesting object in our sample is the Tidal Dwarf Galaxy candidate ce-061 in the galaxy merger IC 1182.

Domaines: Astrophysique [astro-ph]

Jorge Iglesias-Páramo, Willem van Driel, Pierre-Alain Duc, Polychronis Papaderos, Jose M. Vílchez, et al.. A study of H I-selected galaxies in the Hercules cluster. Astronomy and Astrophysics - A&A, 2003, 406, pp.453-469. ⟨10.1051/0004-6361:20030626⟩. ⟨hal-03785073⟩