Stars and gas in the Medusa merger

Abstract

The Medusa (NGC 4194) is a well-studied nearby galaxy with the disturbed appearance of a merger and evidence for ongoing star formation. In order to test whether it could be the result of an interaction between a gas-rich disk-like galaxy and a larger elliptical, we have carried out optical and radio observations of the stars and the gas in the Medusa, and performed $N$-body numerical simulations of the evolution of such a system. We used the Nordic Optical Telescope to obtain a deep V-band image and the Westerbork Radio Synthesis Telescope to map the large-scale distribution and kinematics of atomic hydrogen. A single HI tail was found to the South of the Medusa with a projected length of 56 kpc (5') and a gas mass of 7* 10^8 M_sun, thus harbouring about one third of the total HI mass of the system. HI was also detected in absorption toward the continuum in the center. HI was detected in a small nearby galaxy to the North-West of the Medusa at a projected distance of 91 kpc. It is, however, unlikely that this galaxy has had a significant influence on the evolution of the Medusa. The simulations of the slightly prograde infall of a gas-rich disk galaxy on an larger, four time more massive elliptical (spherical) galaxy reproduce most of the observed features of the Medusa.Thus, the Medusa is an ideal object to study the merger-induced star formation contribution from the small galaxy of a minor merger.

arXiv commentaccepted by A&A, 16 pages, movies of the simulations can be found at http://www.bjerkeli.se/

References in corpus (13)

• Star Formation in Galaxies Along the Hubble Sequence
• Gasdynamics and Starbursts in Major Mergers
• The IRAS Revised Bright Galaxy Sample (RBGS)
• The effect of galaxy mass ratio on merger--driven starbursts
• Galaxy mergers with various mass ratios: properties of remnants
• Lost & Found Dark Matter in Elliptical Galaxies
• Faint Radio Sources and Star Formation History
• Faint Radio Sources and Star Formation History
• Mass-to-light ratio gradients in early-type galaxy haloes
• The Neutral Hydrogen Distribution in Merging Galaxies: Differences between Stellar and Gaseous Tidal Morphologies
• Triggering of merger-induced starbursts by the tidal field of galaxy groups and clusters
• A Molecular Tidal Tail in the Medusa Minor Merger
• Sub-arcsecond imaging of the radio continuum and neutral hydrogen in the Medusa merger

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• Diffuse X-ray-emitting Gas in Major Mergers
• Molecular tendrils feeding star formation in the Eye of the Medusa - The Medusa merger in high resolution 12CO 2-1 maps
• Clues on Arp 142: The Spiral-Elliptical merger