A Carbon star approach to IC 10: Distance and correct size ^*,**

¹ Département de Physique, Université de Montréal, CP 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada e-mail: demers@astro.umontreal.ca
² INAF – Osservatorio Astronomico di Roma, Viale del Parco Mellini 84, 00136 Roma, Italia e-mail: battinel@oarhp1.rm.astro.it
³ Kapteyn Astronomical Institute, Posbus 800, Groningen, 9700 AV, The Netherlands e-mail: bruno@astro.rug.nl

Received: 29 March 2004
Accepted: 26 May 2004

Abstract

We present wide field CFH12K observations of the highly reddened Local Group galaxy IC 10. Using R, I, CN and TiO filters we identify 676 carbon stars in the field of IC 10. After mapping the reddening in the field, from the colours of the G dwarfs seen along the line of sight, we determine the mean apparent magnitude of the C star population to be , leading to a true modulus of ( kpc). The old red giant stars define an asymmetric halo. With a halo diameter of at least 30', IC 10 is among the largest dwarfs of the Local Group. The surface density of C stars follows a radial power law with a scale length of 2.36', a value nearly identical to the scale length defined by the old giants thus IC 10 has a stellar halo where the old and intermediate-age populations are well mixed.