Stellar and substellar mass function of the young open cluster candidates Alessi 5 and beta Monocerotis

TL;DR

This study conducts optical and infrared surveys of the young open clusters Alessi 5 and beta Monocerotis to analyze their stellar and substellar mass functions, revealing similarities with older clusters despite age differences.

Contribution

It provides new photometric data and preliminary mass functions for Alessi 5 and beta Monocerotis, focusing on very-low mass stars and brown dwarfs in young clusters.

Findings

Mass function of Alessi 5 is similar to that of the Hyades.

Survey sensitivity extends to brown dwarfs of 30 M_Jup.

Preliminary results suggest consistent mass distribution across different cluster ages.

Abstract

Although the stellar and substellar populations have been studied in various young and old open clusters, additional studies in clusters in the age range from 5 to 100 Myr is crucial (e.g. to give more constrains on initial mass function variation with improved statistics). Among the open cluster candidates from recent studies, two clusters are best suited for photometric survey of very-low mass stars and brown dwarfs, considering their youth and relative proximity: Alessi 5 (t ~ 40 Myr, d ~ 400 pc) and beta Monocerotis (t ~ 9.1 Myr, d ~ 400 pc). For both clusters, we performed an optical and near-infrared photometric survey, and a virtual observatory survey. Our survey is predicted to be sensitive from the massive B main sequence stars down to brown dwarfs of 30 M_Jup. Here, we present and discuss preliminary results, including the mass function obtained for Alessi 5, which is surprisingly very similar to the mass function of the Hyades (t ~ 600 Myr), although they are of very different ages.