Infrared Spectral Energy Distributions of Giant HII Regions in M33

Session 10 - Interstellar Medium and Star Formation.
Display session, Monday, June 08
Atlas Ballroom,

[10.14] Infrared Spectral Energy Distributions of Giant HII Regions in M33

B. P. Skelton, E. A. Magnier (U. Washington), T. R. Bontekoe (Bontekoe Data Consultancy), D. J. M. Kester (SRON Lab. for Space Research Groningen)

Infrared spectral energy distributions of four giant HII regions (GHRs) in the nearby spiral galaxy M33 have been constructed from deconvolved IRAS images (see Bontekoe et al., 1994, Aamp;A, 284, 1037). These GHRs, NGC 604, NGC 595, NGC 588, and IC 133, are at various galactocentric radii; only NGC 595 is not well separated from other infrared sources in M33.

The variations in the infrared emission of these GHRs are compared by way of their optical emission-line properties. The GHRs in the sample have been imaged at H\alpha, H\beta, [SII], and [OIII]. All these GHRs have metallicities between approximately 25 and 50% solar, but their emission-line properties differ greatly. The diversity in the observed ratios of fluxes in these lines indicates that physical conditions such as temperature, stellar content, and excitation by shocks vary among the GHRs.

In addition to the four GHRs, the infrared emission of the center of M33 is examined. Though the crowding is too great to assign the infrared flux to any particular object, the integrated optical properties of HII regions near the nucleus are calculated. The optical and infrared emission of the central region of the galaxy is then compared with the sample of GHRs.

Program listing for Monday