The motion of variable stars in the Gaia colour magnitude diagram

A video showing the motion of variable stars in the Hertzsprung-Russell Diagram, created by Krzysztof Nienartowicz, Laurent Eyer, Lorenzo Rimoldini and the whole CU7/DPCG Geneva and international DPAC teams

The movie presents the motion of some variable stars in the colour-absolute magnitude diagram in terms of absolute G magnitude versus BP-RP colour (with no correction for extinction). The absolute magnitude is derived with the G band photometry and the Gaia parallax. Each moving point represents a specific variable star, after interpolating between successive Gaia measurements to show a continuous motion. Because of this interpolation, some motions may be faster in reality than they appear in this movie.

Objects were selected to avoid too much crowding. We remark that some variable phenomena are very clumped in this diagram and others are more extended. We include also the motions of stars whose time series and variability types are not published in the second data release, to illustrate the strength of Gaia with nearly simultaneous measurements of astrometry, photometry, spectrophotometry. In future Gaia data releases, we will also add radial velocity time series.

We represented variable phenomena of different physical origins: pulsation, eclipse, rotation, eruption and cataclysmic events. The background density in grey serves to keep a footprint of the classical location of stars in such a diagram. We remark that interstellar extinction tends to displace stellar positions in this diagram towards the lower-right direction (fainter and redder).

Credits: ESA/Gaia/DPAC, Krzysztof Nienartowicz, Laurent Eyer, Lorenzo Rimoldini, Olivier Marchal, Florian Glass and the entire CU7/DPCG Geneva and international teams

Published: 25 April 2018, Updated: 03/05/2018

A guide for Scientists - Gaia DR2 Variable Stars