Astron. Astrophys. Suppl. Ser. 145, 377-397

Mapping the star formation history of Mrk 86

I. Data and models

A. Gil de Paz¹ - J. Zamorano¹ - J. Gallego¹ - F. de B. Domínguez²

Send offprint request: A. Gil de Paz

1 - Departamento de Astrofísica, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid, Spain
2 - OTRI, Universidad Carlos III de Madrid, C/ Butarque, 15, E-28911 Leganés, Spain
e-mail: gil@astrax.fis.ucm.es (AGdP)

Received November 23, 1999; accepted June 8, 2000

 

Abstract:

We have obtained optical (BVR, [O III]$\lambda$5007 Å and H$\alpha$), 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 H$\alpha$ luminosity distributions of the galaxy star-forming regions show maxima at M_R=-9.5^m and $L_{\mathrm{H}\alpha}=10^{37.3}~{\rm erg\,s}^{-1}$. The underlying stellar population shows an exponential surface brigthness profile with central value, $\mu_{\mathrm{E,0}}=21.5~{\rm mag\,arcsec}^{-2}$, 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, $1/50\,Z_{\hbox{$\odot$ }}<Z<2\,Z_{\hbox{$\odot$ }}$, and burst strength, 1-10^-4. These models include nebular continuum and recombination and forbidden-line emission.

Key words: individual: Mrk 86 -- galaxies: irregular, star clusters, stellar content