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A tale of three cities - OmegaCAM discovers multiple sequences in the color-magnitude diagram of the Orion Nebula Cluster

Wright, Nicholas J.

A tale of three cities - OmegaCAM discovers multiple sequences in the color-magnitude diagram of the Orion Nebula Cluster Thumbnail


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Abstract

As part of the accretion discs in Ha with OmegaCAM (ADHOC) survey, we imaged a region of 12 × 8 square degrees around the Orion Nebula Cluster in r, i and Ha. Thanks to the high-quality photometry obtained, we discovered three well-separated pre-main sequences in the color-magnitude diagram. The populations are all concentrated towards the cluster’s center. Although several explanations can be invoked to explain these sequences, we are left with two competitive but intriguing scenarios: a population of unresolved binaries with an exotic mass ratio distribution, or three populations with different ages. Independent high-resolution spectroscopy supports the presence of discrete episodes of star formation, each separated by about a million years. The stars from the two putative youngest populations rotate faster than the older ones, in agreement with the evolution of stellar rotation observed in pre-main sequence stars younger than 4 Myr in several star forming regions.? Whatever the final explanation, our results prompt a revised look at the formation mode and early evolution of stars in clusters.

Acceptance Date May 26, 2017
Publication Date Jul 27, 2017
Publicly Available Date Mar 28, 2024
Journal Astronomy and Astrophysics
Print ISSN 2329-1273
Publisher Hans Publishers
Pages A22 - A22
DOI https://doi.org/10.1051/0004-6361/201730432
Keywords stars: pre-main sequence, open clusters and associations: individual: Orion
Publisher URL https://doi.org/10.1051/0004-6361/201730432

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