Study of star formation in NGC 1084

TL;DR

This study investigates star formation in NGC 1084 through multi-band photometry and spectroscopy, revealing recent bursts likely triggered by a galaxy merger, with detailed analysis of star formation rates, ages, and metallicity.

Contribution

It provides new insights into the star formation history and triggers in NGC 1084 using combined photometric and spectroscopic data, including age and metallicity estimates.

Findings

Star formation rates up to 0.5 solar masses per year.

Star formation occurred in bursts over the last 40 million years.

Metallicity close to solar value.

Abstract

We present UBVRI broad band, H$\alpha$ narrow band photometry of the star forming complexes in the infra-red bright galaxy NGC 1084. Results of medium resolution spectroscopy of some of the brighter complexes are also discussed. Spectroscopic data is used to better estimate the internal reddening within the galaxy which is found to be highly variable and to calculate metallicity which is close to the solar value. Diagnostic diagram identifies the shocked regions within this galaxy. The narrow band H$\alpha$ flux and its equivalent width are used to determine the star formation rates of the complexes and the distribution of ages. Star formation rates for a few of the complexes are found to be as high as 0.5 $M_{\odot}$/year. The star forming complexes lie in the age range 3 Myr to 6.5 Myr. U-B vs V-I colour-colour mixed population model created using the Starburst99 model colours is used to estimate the ages of the stellar populations present within these regions. Using this technique, it is found that the star formation in NGC 1084 has taken place in a series of short bursts over the last 40 Myr or so. It is proposed that the likely trigger for enhanced star formation is merger with a gas rich dwarf galaxy.