SIMBAD references

1999AJ....117.1249D - Astron. J., 117, 1249-1274 (1999/March-0)

The ionizing star clusters of giant H II regions in NGC 2403.


Abstract (from CDS):

We present the results of a study on the massive star population down to about MV~-3.1, or 12-15 M, of the most luminous giant H II regions in the nearby spiral galaxy NGC 2403, based on Hubble Space Telescope images and ground-based spectrograms. Particular emphasis is placed on the distribution of the Wolf-Rayet and red supergiant stars and the information they provide about the recent star-forming history of these large complexes. We find direct evidence for the presence of Wolf-Rayet (WR) stars in five of the six giant H II regions investigated; 25-40 WR stars are inferred for the sole NGC 2403-I giant H II region. Red supergiant (RSG) stars are mainly distributed over a more extended halo, while the young blue stars and most WR stars are in or close to a compact core. One appears to be seeing young cores of O and WR stars surrounded by older halos containing red supergiants. We propose a scenario in which RSG stars belonging to an early phase of star formation were followed by a more recent burst corresponding to a very blue mean sequence. Delayed trigger with preheating over several 100 pc by the first generation of massive stars allowed the build-up of the required confinement for the production of parsec-scale cluster cores with luminosity up to a few times 106 L. Finally, we present some interesting objects found in the field of NGC 2403 outside the giant H II regions, such as field WR stars, globular clusters and background galaxies.

Abstract Copyright:

Journal keyword(s): Galaxies: Individual: NGC Number: NGC 2403 - ISM: H II Regions - Stars: Evolution - Stars: Wolf-Rayet

Nomenclature: Table 1: [DRM99] NGC 2403 R (Nos I-VI). Table 2: [DRM99] NGC 2403 R-NN N=50. Fig.6: [DRM99] NGC 2403 I A (Nos A-D). Fig.8: [DRM99] NGC 2403 I EMN (Nos EM1-EM5). Fig.16b: [DRM99] NGC 2403 IV A (No. A). Table 4: [DRM99] 4-NN (Nos 4-1 to 4-52). Table 5: [DRM99] 5-NN (Nos 5-1 to 5-25).

Simbad objects: 164

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