Despite advances in observational astronomy, much of the Milky Way remains hidden due to the obscuring effects of the interstellar medium and our position within the galactic disc. Historically, surveys focused on stars near the Sun have dominated our understanding. To overcome these limitations, AIP researchers, alongside collaborators from the University of Vienna and the Paris Observatory, analyzed the orbits of stars rather than isolated observations. Their method leverages data from the APOGEE survey, part of the Sloan Digital Sky Survey, to calculate the orbits of stars and their associated mass distribution.

This innovative technique allowed the team to map stellar kinematics across the Milky Way, including previously inaccessible regions like the bar area. Sergey Khoperskov, lead author of the study, explained: "We can look at this approach from a different perspective. Imagine that for every star we observe, there is a large sample of stars that follow exactly the same orbit but, for various reasons, weren't captured by the survey. What we are doing is reconstructing the positions, velocities and stellar parameters of these invisible stars, filling in the missing pieces of the Galaxy's structure."

Through this method, the researchers reconstructed the Galaxy's mass-weighted chemical abundances and age distribution. Their findings highlight two distinct phases of the Milky Way's formation. The inner disc formed rapidly during the galaxy's early history, while the outer disc began assembling approximately 6 - 7 billion years ago, significantly expanding its radial extent.

This research provides critical insights into the Milky Way's past and present, allowing for a panoramic view of its structure. By bypassing observational limitations, the team has unlocked a deeper understanding of the galaxy's chemical and kinematic properties, bridging gaps in our knowledge of its evolutionary timeline.

Research Report:Rediscovering the Milky Way with orbit superposition approach and APOGEE data I. Method validation

Research Report:Rediscovering the Milky Way with orbit superposition approach and APOGEE data II. Chrono-chemo-kinematics of the disc

Research Report:Rediscovering the Milky Way with orbit superposition approach and APOGEE data III. Panoramic view of the bulge

Related Links
Leibniz Institute for Astrophysics Potsdam
Stellar Chemistry, The Universe And All Within It