The Nearby, Young, Chi1 Fornacis Cluster: Membership, Age, and an Extraordinary Ensemble of Dusty Debris Disks

Abstract

Only four star clusters are known within ~100 pc of Earth. Of these, the Chi1 For cluster has barely been studied. We use the Gaia DR2 catalog and other published data to establish the cluster membership, structure, and age. The age of and distance to the cluster are ~40 Myr and 104 pc, respectively. A remarkable, unprecedented, aspect of the cluster is the large percentage of M-type stars with warm excess infrared emission due to orbiting dust grains -- these stars lie in an annulus that straddles the tidal radius of the cluster. The Chi1 For cluster appears to be closely related to two extensive, previously known, groups of co-moving, coeval stars (the Tucana-Horologium and Columba Associations) that are spread over much of the southern sky. While Tuc-Hor and Chi1 For are comoving and coeval, the difference in the frequency of their warm dusty debris disks at M-type stars could hardly be more dramatic.

This October 2019 version of the paper replaces the initial (September 2019) version. The most important changes are a slight renumbering (renaming) of most of the ChiFor stars in Tables 1 and 2 and the addition of a Note Added in Proof

References in corpus (5)

• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• A Stellar Census of the Tucana-Horologium Moving Group
• Warm Dusty Debris Disks and Distant Companion Stars: V488 Per and 2M1337
• Jet Kinematics of the Quasar 4C +21.35 from Observations with the KaVA Very Long Baseline Interferometry Array
• Nearby Young, Active, Late-type Dwarfs in Gaia's First Data Release

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• Disks in Nearby Young Stellar Associations Found Via Virtual Reality
• Walking the Line: Young Stars on the Boundary of the Epsilon Cha and Lower Centaurus-Crux Associations
• Characterizing bright $\delta$ Scuti pulsators using TESS lightcurves
• Nearby Young Stars and Young Moving Groups