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New Infrared Observations of NGC 3603

Published online by Cambridge University Press:  04 August 2017

M. Roth
Affiliation:
Instituto de Astronomía, Universidad Nacional Autónoma de México, México
M. Tapia
Affiliation:
Instituto de Astronomía, Universidad Nacional Autónoma de México, México
M. T. Ruiz
Affiliation:
Departamento de Astronomía, Universidad de Chile, Chile
P. Persi
Affiliation:
Istituto Astrofísica Spaziale, CNR, Frascati, Italy
M. Ferrari-Toniolo
Affiliation:
Istituto Astrofísica Spaziale, CNR, Frascati, Italy

Extract

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NGC 3603, one of the most massive H II regions in our galaxy, shows recent star forming activity (Frogel et al. 1977; Tapia 1981; Persi et al., 1985). In this paper we report new near-infrared maps and photometric observations in the complex region surrounding Irs 9, Irs 2 and Irs 8. Most data were gathered at the 1.5-m telescope of CTIO, using an InSb photometer. Tables 1 and 2 synthesize the observations and the results of the photometry. While the low resolution K map (Figure 1) shows basically the previously reported features, the high resolution K and L maps (shown superimposed in Figure 2), show that Irs 9 is the brightest source in the field, clearly resolved from Irs 2 and Irs 8. The presence of a previously unreported source some 22″N and 5″W of Irs 2, should be further investigated. The spectral distributions derived from our measurements and from previous ones by Persi et al. (1985) strongly suggest that the 10 and 20 μm fluxes reported by Frogel et al. (1977) at the position of Irs 2, probably correspond to Irs 9. Under this assumption, Irs 9 is probably a highly reddened massive star (1 μm to 20 μm luminosity, L = 2.2 × 104 L) while the luminosity of Irs 2 is less than 102 L. We therefore conclude that Irs 9 is a young massive star surrounded by a warm (Tdust ∼ 250 K) dust envelope; Irs 2 seems to be the less obscured part of an associated H II region, as further corroborated by the Brγ emission and the free-free like spectrum and spectral distribution, as reported by Persi et al. (1985) and in this paper.

Type
I. Star Forming Processes in the Solar Neighborhood
Copyright
Copyright © Reidel 1987 

References

Frogel, J., Persson, C., and Aaronson, M.: 1977, Astrophys. J. 213, 723.CrossRefGoogle Scholar
Persi, P., Tapia, M., Roth, M., and Ferrari-Toniolo, M.: 1985, Astron. Astrophys. 144, 275.Google Scholar
Tapia, M.: 1981, Monthly Notices. Roy. Astron. Soc. 197, 949.CrossRefGoogle Scholar