Phase-space structures and stellar populations in the star-forming region NGC~ 2264

TL;DR

This study uses the Spectrum of Kinematic Groupings to analyze phase-space substructures in NGC 2264, revealing hierarchical structures linked to different stellar populations and background features, demonstrating the method's effectiveness in stellar population analysis.

Contribution

Introduces an objective, scalable methodology using SKG to identify and compare phase-space substructures in star-forming regions and the background, linking structures to stellar ages and populations.

Findings

Detected hierarchical substructure in NGC 2264 consistent with previous studies.

Identified background structures possibly related to the Outer Arm or Monoceros Ring.

Confirmed the link between phase-space structures and stellar population properties.

Abstract

In this work we analyse the structure of a subspace of the phase space of the star-forming region NGC~ 2264 using the Spectrum of Kinematic Groupings (SKG). We show that the SKG can be used to process a collection of star data to find substructure at different scales. We have found structure associated with the NGC~ 2264 region and also with the background area. In the NGC~ 2264 region, a hierarchical analysis shows substructure compatible with that found in previous specific studies of the area but with an objective, compact methodology that allows us to homogeneously compare the structure of different clusters and star-forming regions. Moreover, this structure is compatible with the different ages of the main NGC~ 2264 star-forming populations. The structure found in the field can be roughly associated with giant stars far in the background, dynamically decoupled from NGC~ 2264, which could be related either with the Outer Arm or Monoceros Ring. The results in this paper confirm the relationship between structure in the RV phase-space subspace and different kinds of populations, defined by other variables not necessarily analysed with the SKG, such as age or distance, showing the importance of detecting phase-space substructure in order to trace stellar populations in the broadest sense of the word.