Dwarf Galaxies: From the Deep Universe to the Present Proceedings IAU Symposium No. 344, 2019 K. B. W. McQuinn & S. Stierwalt, eds. c  International Astronomical Union 2019 doi:10.1017/S1743921318006774 The massive stellar population of IC 10 Luis J. Corral 1 , Miriam Garc´ ıa 2 , Silvana G. Navarro 1 and Artemio Herrero 3 1 Intituto de Astronom´ ıa y Meteorolog´ ıa, Universidad de Guadalajara Av. Vallarta 2602, Guadalajara, 44130, Mexico email: lcorral, silvana@astro.iam.udg.mx 2 Centro de Astrobiolog´ ıa (CSIC/INTA), Instituto Nacional de T´ ecnica Aeroespacial, Ctra. de Torrej´ on de Ajalvir, km 4, E-28850, Madrid, Spain email: mggr@cab.inta-csic.es 3 Instituto de Astrof´ ısica de Canarias, C/ V´ ıa L´ actea s/n E-38205 La Laguna, Tenerife, Spain email: ahd@iac.es Abstract. Using photometric data available in the literature we want to identify the massive stars members of the metal-poor irregular galaxy IC 10 and the clusters and associations that they form. The census of the clusters and associations of these objects is needed to provide information about age and environment on this galaxy that is apparently going through a starburst phase. Keywords. stars: early-type, galaxies: irregular, stellar population, starburst 1. Introduction IC 10 is a metal-poor (Z ∼ 0.36 Z SUN , Garnett (1990)) dwarf irregular galaxy of the Local Group. It lies at a low galactic latitude (l = 119 ◦ .0, b= -3 ◦ .3), which makes reddening to this object intense and very uncertain. According to Kim et al. (2009) IC 10 is at a distance around 0.7-0.8 Mpc. IC 10 also shows a high star formation rate and a huge number of Wolf-Rayet stars per unit luminosity (Massey & Armandroff 1995). All characteristics suggest that IC 10 is experiencing an intense and very recent burst of star formation. OB associations are an ideal laboratory to study the evolution of massive stars because of their expected small age spread and homogeneous chemical composition. In this work we produce a catalog of OB associations in IC 10, so that the impact of low metallicity on the evolution of massive stars can be evaluated in subsequent follow-up studies. 2. Selection of objects A catalog of UBVRI magnitudes of stellar-like objects in a region ∼ 30 arc min. wide around IC 10 was presented by Massey et al. (2007) (LGGS catalog). The original catalog contains 20663 sources, but only 8173 of them have detections in the U-, B- and V-band simultaneously and (U - B) and (B - V ) errors  0.05. Following Garcia et al. (2009), candidate blue massive stars were chosen from their reddening-free Q parameter (Q = (U - B) - 0.72 × (B - V )) that overcomes the problem of uncertain extinction towards the line of sight. We select objects with Q  -0.5 that corresponds to stars hotter than B5. We found that most of these blue objects are indeed over the optical image of the galaxy, but many others lie at great angular distance from it. If these objects are not IC 10 members they can be hot stellar objects from our own galaxy and therefore the contamination of local sources in the final list could be large. 57 https://www.cambridge.org/core/terms. https://doi.org/10.1017/S1743921318006774 Downloaded from https://www.cambridge.org/core. IP address: 3.80.54.224, on 01 Oct 2021 at 23:18:00, subject to the Cambridge Core terms of use, available at