AAS 198th Meeting, June 2001
Session 9. Dwarf, Irregular and Starburst Galaxies
Display, Monday, June 4, 2001, 9:20am-6:30pm, Exhibit Hall

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[9.10] The Evolution of the Blue Compact Dwarf Galaxies: The case of Mrk~86

A. Gil de Paz (NED), B.F. Madore (NED & Observatories of the Carnegie Institution of Washington), J. Zamorano, J. Gallego (Universidad Complutense de Madrid, Spain), C. Sanchez Contreras (JPL), S. Silich (INAOE, Mexico)

In this poster we present the results from the multi-wavelength study of the dynamical and photometric evolution of the Blue Compact Dwarf galaxy Mrk~86. We have obtained BVRJHK, H\alpha, and [O{\sc iii}]\lambda5007\,Å\ imaging, long-slit optical spectroscopy, and H\alpha Fabry-Perot interferometry for this galaxy. These observations will be complemented in a near future with a map of the molecular gas distribution in the 12CO(1--0) and (2--1) transitions using the 30m Pico de Veleta millimeter telescope.

The analysis of the optical and near-infrared images and optical spectra have revealed the presence of, at least, three different stellar populations. A low-surface-brightness underlying population with an age between 5 and 13\,Gyr, a massive 30\,Myr old central starburst with a stellar mass of about 107\,M\odot, and a total of 46 low-metallicity young star-forming regions.

The comparison of our Fabry-Perot H\alpha velocity field with the galaxy mass-density profile indicates that the current star-formation activity is located in a ring with 800\,pc of radius inclined ~40\circ. This fact, along with the age difference between the central starburst and these young star-forming regions, suggest that the evolution of the massive central starburst could be related with the activation of the most recent star-formation activity. In this sense, hydrodynamical simulations for the evolution of starbursts in dwarf galaxies predict the formation of an expanding shell of swept out interstellar material that, in some cases, could shape a toroid of dense (>60\,M\odot\,pc-2) gas at distances of about 1\,kpc. This scenario, that could explain both the spatial and age distribution of the recent star-formation activity in Mrk~86, will be definitively confirmed (or ruled out) by our future 12CO observations.

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