The Open Cluster NGC 2437 (Messier 46)

TL;DR

This study analyzes the stellar content, structure, and star shedding activity of open cluster NGC 2437 using deep imaging, revealing its age, distance, and the distribution of faint stars indicating ongoing star loss.

Contribution

It provides detailed characterization of NGC 2437's stellar population, spatial distribution, and evidence of star shedding, using new deep imaging data and analysis methods.

Findings

Age of NGC 2437 is approximately 200 million years.

Faint main sequence stars are more dispersed and less concentrated.

NGC 2437 is actively losing low-mass stars.

Abstract

The stellar content of the open cluster NGC 2437 (Messier 46) is investigated using moderately deep u*,g', and r' MegaCam images. When compared with solar metallicity isochrones, the (g', u'-g') and (r', g'-r') CMDs are consistent with an age log(t_yr) = 8.35 +/- 0.15, a distance modulus 11.05 +/- 0.05, and a color excess E(B-V) = 0.115 +/- 0.035. The r' luminosity function (LF) of main sequence stars in the magnitude range r' < 17 (i.e. masses > 0.8 solar) has a shape that follows solar neighborhood star counts. However, at fainter magnitudes the cluster LF is flat, in contrast with what would be expected from solar neighborhood counts. The clustering properties of stars in NGC 2437 are investigated by examining the two-point angular correlation functions of main sequence stars in different brightness ranges. Main sequence stars fainter than r' = 17 are less centrally concentrated than brighter stars and are found over a larger area of the sky, suggesting that there is a corona of faint main sequence stars around NGC 2437. Based on the flat LF and extended spatial distribution of faint stars, it is concluded that NGC 2437 is actively shedding stars with masses < 0.8 solar.