The Monitor project: Rotation of low-mass stars in NGC 2362 -- testing the disc regulation paradigm at 5 Myr

TL;DR

This study measures rotation periods of low-mass stars in NGC 2362, examining how their rotation relates to circumstellar discs and testing the disc regulation paradigm at 5 million years.

Contribution

It provides the first rotation period distribution for NGC 2362 and tests the disc regulation paradigm at this age using new photometric data.

Findings

Rotation periods show a mass-dependent distribution similar to other young clusters.

Angular momentum loss models are needed to explain the evolution of slow rotators.

A limited sample suggests slow rotators may have circumstellar discs, supporting the disc regulation paradigm.

Abstract

We report on the results of a time-series photometric survey of NGC 2362, carried out using the CTIO 4m Blanco telescope and Mosaic-II detector as part of the Monitor project. Rotation periods were derived for 271 candidate cluster members over the mass range 0.1 <~ M/Msol <~ 1.2. The rotation period distributions show a clear mass-dependent morphology, qualitatively similar to that in NGC 2264, as would be expected from the age of this cluster. Using models of angular momentum evolution, we show that angular momentum losses over the ~1-5 Myr age range appear to be needed in order to reproduce the evolution of the slowest rotators in the sample from the ONC to NGC 2362, as found by many previous studies. By incorporating Spitzer IRAC mid-IR measurements, we found that 3-4 objects showing mid-IR excesses indicative of the presence of circumstellar discs were all slow rotators, as would be expected in the disc regulation paradigm for early pre-main sequence angular momentum evolution, but this result is not statistically significant at present, given the extremely limited sample size.