Physical Properties of Young Stellar Populations in 24 Starburst Galaxies Observed with FUSE

TL;DR

This study analyzes the physical properties of very young stellar populations in 24 starburst galaxies using FUSE data and spectral synthesis, revealing that most starbursts are not well-represented by continuous star formation models.

Contribution

First comprehensive analysis of young stellar populations in starburst galaxies using FUSE and spectral synthesis, providing detailed physical parameters and testing model limits.

Findings

Most starbursts cannot be modeled by continuous star formation.

Detected underlying stellar populations dominated by B-type stars.

Characterized young stellar populations in Seyfert 2 nuclei under 5 Myr.

Abstract

We presents the main physical properties of very young stellar populations seen with FUSE in 24 individual starbursts. These characteristics have been obtained using the evolutionary spectral synthesis technique in the far-ultraviolet range with the LavalSB code. For each starburst, quantitative values for age, metallicity, initial mass function slope, stellar mass, and internal extinction have been obtained and discussed in details. Limits of the code have been tested. One main conclusion is that most starbursts (and probably all of them) cannot be represented by any continuous star formation burst in the far-ultraviolet. Also, quantitative values of various optical diagnostics related to these stellar populations have been predicted. Underlying stellar populations, dominated by B-type stars, have been detected in NGC 1140, NGC 4449, and possibly NGC 3991. We characterized the young stellar populations of less than 5 Myr in Seyfert 2 nuclei.