Mapping the star formation history of Mrk 86. I. Data and models

Abstract

We have obtained optical (BVR, [O Iii]lambda 5007 Å and Hα ), near infrared (JHK) imaging and long-slit optical spectroscopy for the Blue Compact Dwarf galaxy Mrk 86 (NGC 2537). In this paper, the first of two, we present optical-near-infrared colors and emission-line fluxes for the currently star-forming regions, intermediate aged starburst and underlying stellar population. We also describe the evolutionary synthesis models used in Paper II. The R and Hα luminosity distributions of the galaxy star-forming regions show maxima at M_R=-9.5^m and L_Halpha = 10^37.3 erg s^-1. The underlying stellar population shows an exponential surface brigthness profile with central value, mu_E,0=21.5 mag arcsec^-2, and scale, alpha =0.88 kpc, both measured in the R-band image. In the galaxy outer regions, dominated by this component, no significant color gradients are observed. Finally, a complete set of evolutionary synthesis models have been developed, covering a wide range in metallicity, 1/50 Z_sun <Z<2 Z_sun, and burst strength, 1-10^-4. These models include nebular continuum and recombination and forbidden-line emission. Visiting Astronomer (AGdP), Kitt Peak National Observatory, National Optical Astronomy Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.