Discovery of a nearby stellar stream in Gaia DR2

Extended stellar systems in the solar neighborhood - II. Discovery of a nearby 120° stellar stream in Gaia DR2

We report the discovery of a large, dynamically cold, coeval stellar stream that is currently traversing the immediate solar neighborhood at a distance of only 100 pc. The structure was identified in a wavelet decomposition of the 3D velocity space of all stars within 300 pc to the Sun. Its members form a highly elongated structure with a length of at least 400 pc, while its vertical extent measures only about 50 pc. Stars in the stream are not isotropically distributed but instead form two parallel lanes with individual local overdensities, that may correspond to a remnant core of a tidally disrupted cluster or OB association. Its members follow a very well-defined main sequence in the observational Hertzsprung-Russell diagram and also show a remarkably low 3D velocity dispersion of only 1.3 km/s. These findings strongly suggest a common origin as a single coeval stellar population.

http://arxiv.org/abs/1901.06387