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arXiv · 2412.05401

Rotational Velocities and Radii Estimates of Low-Mass Pre-Main Sequence Stars in NGC 2264

Laurin M. Gray·Katherine L. Rhode·Catrina M. Hamilton-Drager·Tiffany Picard·Luisa M. Rebull
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Abstract

Investigating the angular momentum evolution of pre-main sequence (PMS) stars provides important insight into the interactions between Sun-like stars and their protoplanetary disks, and the timescales that govern disk dissipation and planet formation. We present projected rotational velocities (v sin i values) of 254 T Tauri stars (TTSs) in the ~3 Myr-old open cluster NGC 2264, measured using high-dispersion spectra from the WIYN 3.5m telescope's Hydra instrument. We combine these with literature values of temperature, rotation period, luminosity, disk classification, and binarity. We find some evidence that Weak-lined TTSs may rotate faster than their Classical TTS counterparts and that stars in binary systems may rotate faster than single stars. We also combine our v sin i measurements with rotation period to estimate the projected stellar radii of our sample stars, and then use a maximum likelihood modeling technique to compare our radii estimates to predicted values from stellar evolution models. We find that starspot-free models tend to underestimate the radii of the PMS stars at the age of the cluster, while models that incorporate starspots are more successful. We also observe a mass dependence in the degree of radius inflation, which may be a result of differences in the birthline location on the HR diagram. Our study of NGC 2264 serves as a pilot study for analysis methods to be applied to four other clusters ranging in age from 1 to 14 Myr, which is the timescale over which protoplanetary disks dissipate and planetary systems begin to form.

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Laurin M. Gray, Katherine L. Rhode, Catrina M. Hamilton-Drager, Tiffany Picard, Luisa M. Rebull. 2024-12-06. Rotational Velocities and Radii Estimates of Low-Mass Pre-Main Sequence Stars in NGC 2264. https://doi.org/10.3847/1538-4357%2Fad924b

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