Hidden power of near-infrared data for the study of young clusters: Illustrative case of RCW 38

TL;DR

This paper demonstrates that near-infrared data alone can be used to determine distances, membership, and excess emission fractions in young star clusters, providing a new approach that reduces reliance on multi-wavelength data.

Contribution

The study introduces a method to infer cluster properties and membership solely from near-infrared data, offering a more accessible and less biased analysis tool for young stellar clusters.

Findings

Estimated the distance to RCW 38 as 1.5 kpc.

Determined that over 60% of sources have $2.2~bc$m excess emission.

Showed that traditional mass inference methods may be unreliable.

Abstract

Studies of star formation rely heavily on observations in the near-infrared, but they typically need information from other wavelengths for interpretation. We show that we can infer distances and estimate the membership of young stellar objects for young clusters independently using (ground-based) near-infrared, $J$, $H,$ and $K_S$ broadband data alone. We also show that we can estimate a lower limit for the fraction of sources with $2.2~\mu$m excess emission with a sensitivity comparable to that of mid-infrared space data, but with better resolution and fewer biases. Finally, we show that the typical methods for inferring masses from these data may produce substantially unreliable results. This method is applied to the young, massive cluster RCW 38, for which we estimate a distance of 1.5 kpc and a $K_S$-band excess fraction larger than 60\%.