Discovery of a young stellar "snake" with two dissolving cores in the solar neighborhood

Abstract

We report the discovery of a young (only 30-40\,Myr) snake-like structure (dubbed a stellar "snake") in the solar neighborhood from {\it Gaia} DR2. The average distance of this structure is about 310\,pc from us. Both the length and width are over 200\,pc, but the thickness is only about 80\,pc. The "snake" has one tail and two dissolving cores, which can be clearly distinguished in the 6D phase space. The whole structure includes thousands of members with a total mass of larger than 2000\,$M_{\odot }$ in an uniform population. The population is so young that it can not be well explained with the classical theory of tidal tails. We therefore suspect that the "snake" is hierarchically primordial, rather than the result of dynamically tidal stripping, even if the "snake" is probably expanding. The coherent 5D phase information and the ages suggest that the "snake" was probably born in the same environment as the filamentary structure of Beccari et al.(2020). If so, the "snake" could extend the sky region of the Vela OB2 association by a factor of $\sim 2$, and supplement the census of its coeval structures. This finding is useful to understand the history of the formation and evolution of the Vela OB2 complex. The age of the "snake" well matches with that of the Gould Belt. In the sky region of our interest, we detect one new open cluster, which is named as Tian 1 in this work.

9 pages, 5 figures, and 1 table, accepted for publication in the ApJ

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• 3D Morphology of Open Clusters in the Solar Neighborhood with Gaia EDR3: its Relation to Cluster Dynamics
• Hunting for Neighboring Open Clusters with Gaia DR3: 101 New Open Clusters within 500 pc
• A Blind All-sky Search for Star Clusters in Gaia EDR3: 886 Clusters within 1.2 kpc of the Sun
• Rotation and Lithium Confirmation of a 500 Parsec Halo for the Open Cluster NGC 2516
• A 38 Million Year Old Neptune-Sized Planet in the Kepler Field
• Low Mass Stars as Tracers of Star and Cluster Formation
• A Young, Low-Density Stellar Stream in the Milky Way Disk: Theia 456
• Disconnecting the Dots: Re-Examining the Nature of Stellar "Strings" in the Milky Way
• A revisited study of Cepheids in open clusters in the Gaia era
• Precise Ages of Field Stars From White Dwarf Companions in Gaia DR2
• The Stellar "Snake" I: Whole Structure and Properties
• A GALAH View of the Chemical Homogeneity and Ages of Stellar Strings Identified in Gaia
• Toward the fabric of the Milky Way I. The density of disk streams from a local $250^3$ pc${}^3$ volume