Gaia in the UK

Taking the Galactic Census

Gaia Catalogue of Nearby Stars - orbits

Gaia Early Data Release 3 - Gaia Catalogue of Nearby Stars - Orbits

This animation shows the orbits of stars from the Gaia Catalogue of Nearby Stars (within 100 pc), having a radial velocity in Gaia Early Data Release 3 (EDR3) (74 281). The orbits have been computed taking into account the gravitational potential of the Milky Way, not the environment (gravitation between stars is not included).

The starting point of the video is today, where we can see the 100 pc sphere around the Sun superimposed on the artistic view of the Milky Way with 3 orientations: top-down view, side-view, and perspective-view. The field of view is 100 000 light-year wide (30.66 kpc).

The video shows the motion of the stars over 500 Myr (6 Myr/second).

Most of the stars have a disc-like orbit, similar to the Sun, with small eccentricity and close to the Galactic plane. However the solar neighbourhood is also visited by stars from the halo (orange dots, with larger eccentricities, and going in the outer parts of the Galaxy, away from the Galactic plane) and stars coming from/going to the inner parts of the galaxy (yellow dots). The Hyades and Coma Berenice clusters are also clearly visible as small clumps (blue dots).

Large-scale features rapidly appear (also seen as "lines" in the side view). They are related to substructures visible today in the kinematic plane. Having similar velocities, the stars from these substructures are diluted in the space with time but share similar orbits. 

After about 130 Myr, all the stars of moderate eccentricity again reach exactly the same galactocentric distance at which they started. Because their orbital periods are different, they do not meet exactly after one such period (radial libration period), but are already a bit stretched out in longitude. On the long run, this effect leads the stars to form a long ribbon that eventually winds itself all the way around the galaxy. It is the same mechanism that produces meteor streams in the solar system and tidal tails of galactic star clusters. The radial libration period is different from the orbital period because the galactic central field is not Keplerian.

Image credit: ESA/Gaia/DPAC

Released under CC BY-SA 3.0 IGO

Acknowledgement: This video was created by S. Payne-Wardenaar, S. Jordan and C. Reylé.

Based on the data provided in the paper Gaia Collaboration, Smart et al. 2020 "Gaia Early Data Release 3: the Gaia Catalogue of Nearby Stars".

Page last updated: 03 December 2020