A detailed study of the enigmatic cluster M82F

TL;DR

This study provides a comprehensive analysis of the stellar cluster M82F, revealing its substructure, size, age, and extinction properties, but does not resolve the high light-to-mass ratio or IMF characteristics.

Contribution

It offers the first detailed multi-band imaging and spectroscopy analysis of M82F, including spatially resolved extinction mapping and revised cluster size estimates.

Findings

Cluster size is 15-30% larger than previous estimates.

Age of the cluster is determined to be 60-80 Myr.

No strong evidence of mass segregation found.

Abstract

We present a detailed study of the stellar cluster M82F, using multi-band high resolution HST imaging and deep ground based optical slit and integral field spectroscopy. Using the imaging we create colour maps of the cluster and surrounding region in order to search for substructure. We find a large amount of substructure, which we interpret as the result of differential extinction across the projected face of the cluster. With this interpretation, we are able to construct a spatially resolved extinction map across the cluster which is used to derive the intrinsic flux distribution. Fitting cluster profiles (King and EFF) to the intrinsic images we find that the cluster is 15-30% larger than previous estimates, and that no strong evidence of mass segregation in this cluster exists. Using the optical spectra, we find that the age of M82F is 60-80 Myr and from its velocity conclude that the cluster is not physically associated with a large HII region that it is projected upon, both in agreement with previous studies. The reconstructed integral field maps show that that majority of the line emission comes from a nearby HII region. The spatial dependence of the line widths (implying the presence of multiple components)measured corresponds to the extinction map derived from photometry, indicating that the gas/dust clouds responsible for the extinction are also partially ionised. Even with the wealth of observations presented here, we do not find a conclusive solution to the problem of the high light-to-mass ratio previously found for this cluster and its possible top-heavy stellar IMF.