The Relation between Galaxy Activity and the Dynamics of Compact Groups of Galaxies

Peer reviewe

H I Recycling: Formation of Tidal Dwarf Galaxies

Original paper can be found at: http://www.astrosociety.org/pubs/cs/222-252.html--Copyright Astronomical Society of the PacificGalactic collisions trigger a number of phenomena, such as transportation inward of gas from distances of up to kiloparsecs from the center of a galaxy to the nuclear region, fueling a central starburst or nuclear activity. The inverse process, the ejection of material into the intergalactic medium by tidal forces, is another important aspect and can be studied especially well through detailed HI observations of interacting systems. These studies have shown that a large fraction of the gaseous component of colliding galaxies can be expelled. Part of this tidal debris might fall back, be dispersed throughout the intergalactic medium or re-condense to form a new generation of galaxies: the so-called tidal dwarf galaxies. The latter are nearby examples of galaxies in formation. The properties of these recycled objects, and different ways to identify them, are reviewed here

VLA HI imaging of the Low Surface Brightness dwarf galaxy DDO47

Original paper can be found at: http://www.astrosociety.org/pubs/cs/156-194.html--Copyright Astronomical Society of the PacificWe present high resolution VLA-observations of the nearby Low Surface Brightness Galaxy DDO 47. This object shows many hole-like structures in its neutral interstellar medium. The majority of the detected H I-shells are found to be expanding. Their origin is therefore believed to be due to stellar winds of the most massive stars and their subsequent supernova (SN type II) explosions within regions of recent star formation

Spitzer Space Telescope IRAC and MIPS observations of the interacting galaxies Ic 2163 and NGC 2207: clumpy emission

Peer reviewe

CO Observations of the Interacting Galaxy Pair NGC 5394/95

Peer reviewe

Identification and Analysis of Young Star Cluster Candidates in M31

We present a method for finding clusters of young stars in M31 using broadband WFPC2 data from the HST data archive. Applying our identification method to 13 WFPC2 fields, covering an area of ~60 arcmin^2, has revealed 79 new candidate young star clusters in these portions of the M31 disk. Most of these clusters are small (~<5 pc) young (~10-200 Myr) star groups located within large OB associations. We have estimated the reddening values and the ages of each candidate individually by fitting isochrones to the stellar photometry. We provide a catalog of the candidates including rough approximations of their reddenings and ages. We also look for patterns of cluster formation with galactocentric distance, but our rough estimates are not precise enough to reveal any clear patterns.Comment: 32 pages, 9 figures, 5 tables, accepted to Ap

A NITROGEN-ENRICHED NEBULA AROUND P-CYGNI

We have detected extended nebular emission in [S II]λλ6716,6731, [N II] λ6584,6584andHα on a long-slit spectrum offset by 9 arcsec from P Cyg. Anomalously strong [Ni II]λ6666.8 emission was also detected. The [S II] doublet ratio yields an electron density of 600 cm–3. The [N II] and [S II] lines have been used to derive an N/S ratio which is insensitive to the adopted value of electron temperature. The N/S ratio is 33 ± 5 by number, five times higher than solar, implying that the material has undergone CN-cycle processing which has converted most of the original carbon into nitrogen