The C star population of DDO 190

¹ INAF, Osservatorio Astronomico di Roma, Viale del Parco Mellini 84, 00136 Roma, Italia e-mail: battinel@oarhp1.rm.astro.it
² Département de Physique, Université de Montréal, CP 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada e-mail: demers@astro.umontreal.ca

Received: 7 February 2005
Accepted: 6 October 2005

Abstract

We have carried out deep R, I, CN, TiO observations of the dwarf irregular galaxy DDO 190. We confirm the existence of an intermediate-age population around this galaxy. The identification of 47 carbon stars seen up to 5 arcmin from the centre of the galaxy implies that the population distribution of DDO 190 is similar to those found in some other Local Group dIrr galaxies. An estimate of the metallicity, [Fe/H] = -1.55 ± 0.12, is obtained based on the observed C/M ratio. From the analysis of star counts, corrected for the radial variation of the incompleteness level, we determine a scale-length α = 40 ± 5'', in agreement with the recent literature.