NGC 2363 is a giant extragalactic H II region, located in the south-west end of the irregular galaxy NGC 2366. It is one of the brightest extragalactic H II regions known, and an ideal subject for our study, since plenty of data are available, both observational and theoretical. Two distinctive knots can be clearly distinguished in the region: throughout this paper, we will always refer to the brightest, youngest knot, often called "knot A''.
NGC 2363 has been observed by several groups (e.g., Peimbert et al. 1986; González-Delgado et al. 1994; Izotov et al. 1997), and modeled by Luridiana et al. (1999) and Drissen et al. (2000) among others, while the temperature-fluctuation parameter has been determined by González-Delgado et al. (1994) in both knots.
In the present work, we will assume that both the stellar cluster and the gas nebula of NGC 2363 are well described by the best-fit model of Luridiana et al. (1999), which is a spherical, hollow, radiation-bounded nebula, consisting of two concentric shells of different densities, ionized by a young cluster undergoing an extended burst of star formation. The properties of the model relevant for this work will be described throughout the text.
Copyright ESO 2001