The Expanding 3 kpc Arms Are Neither Expanding nor Spiral Arms but X1 Orbits Driven by the Galactic Bar
Jayender Kumar, Mark J. Reid, T. M. Dame, Simon P. Ellingsen, Lucas J., Hyland, Andreas Brunthaler, Karl M. Menten, Xing-Wu Zheng, Alberto Sanna

TL;DR
This study uses precise VLBI measurements of water masers to reveal that the so-called Expanding 3-kpc arms are actually X1 orbits driven by the Galactic Bar, challenging previous interpretations of their nature.
Contribution
It provides the first direct measurements of X1 orbits in the Milky Way, linking young stars to the Galactic Bar and clarifying the nature of the 3-kpc arms.
Findings
Expanding 3-kpc arms are likely X1 orbits around the Galactic Bar.
Young stars in these regions are on quasi-elliptical orbits.
Some stars previously thought to be in the Norma spiral arm are in these orbits.
Abstract
Near the center of our Milky Way is a bar-like structure and the so-called Expanding 3-kpc arms. We currently have limited knowledge of this important region, since we are about 8.2 kpc from the center and cannot directly observe it at optical wavelengths, owing to strong extinction from interstellar dust. Here we present extremely precise VLBI measurements of water maser sources from the BeSSeL Survey, where extinction is not a problem, which accurately determine the 3-dimensional locations and motions of three massive young stars. Combined with previous measurements, these stars delineate a trail of orbits outlining the Milky Way's Galactic Bar. We present the first measurements capturing the dynamics of quasi-elliptical (X1) orbits around the Galactic Bar. Our findings provide evidence substantiating the existence of such orbits populated by massive young stars. Our measurements of…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
Taxonomy
TopicsAstro and Planetary Science · Space Satellite Systems and Control
