Astronomers explore the properties of a peculiar stellar stream

Utilizing ESA’s Gaia satellite and the MMT Observatory, astronomers have investigated a peculiar stream of stars in our galaxy named Theia 456. Outcomes of the examine, published Could 21 on the pre-print server arXiv, ship necessary insights into the properties and origin of this stellar stream.

Found in 2019, Theia 456 (also referred to as COIN-Gaia-13) is a stellar stream within the skinny disk of the Milky Way, consisting of about 320 loosely certain stars. The stream extends practically 400 light years in size and 20 levels throughout the sky within the Northern Hemisphere.

Earlier observations of Theia 456 have discovered that it’s a kinematically, chemically, and gyrochronally coherent stellar stream. Nonetheless, many properties of Theia 456 nonetheless stay unsure and its dynamical historical past just isn’t effectively understood.

That’s the reason a group of astronomers led by Kyle Tregoning of the College of Florida determined to conduct follow-up observations of Theia 456 utilizing Gaia and MMT’s Hectochelle multi-object spectrograph.

“On this work, we mix Gaia astrometric portions with MMT-Hectochelle-derived radial velocities to current an in depth dynamical historical past of Theia 456, a stellar stream situated within the skinny disk of the Milky Way,” the researchers wrote.

Tregoning’s group managed to provide a catalog of 321 stars in Theia 456—43 with full 6D phase space info and the remaining 278 with 5D Gaia astrometry. They discovered that, on the whole, the stream consists of about 2,100 stars contributing to a total mass of roughly 900 solar plenty.

The observations discovered that Theia 456 shaped as a low density open cluster and its kinematic age is estimated to be 245 million years. Initially, the cluster had a half-light radius of some 29 gentle years and a velocity dispersion of 0.14 km/s.

The acquired pictures present that Theia 456 has two distinct lobes, which may be indicative of a substructure at delivery. Nonetheless, the astronomers famous that different processes, reminiscent of interplay with a passing large molecular cloud and the Milky Way’s spiral arms, could also be liable for this.

Based mostly on the collected knowledge, the authors of the paper predict that Theia 456 will grow to be extra dispersed sooner or later so it should finally be undetectable as a stellar construction of frequent origin. They assume that the stream will probably grow to be undetectable for our present cluster discovering strategies in lower than 100 million years.

“Inside one other ∼ 100 Myr, the extent of Theia 456 ought to roughly double in right ascension, making this construction unlikely to be recognized by the present era of clustering algorithms,” the scientists concluded.

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