Open clusters dissolve as they age...
...and as they dissolve, they get harder and harder to find, meaning new methods and techniques are required to find extensions to these clusters. My work on open clusters involves using stellar rotation to map their true spatial distribution.
Lost Sisters Found: TESS and Gaia Reveal a Dissolving Pleiades Complex
Check out the paper here, as well as coverage in the New York Times, Scientific American, NASA, Carnegie, UNC, and Sky and Telescope
In this paper, we searched for new members of the Pleiades by using stellar rotation pick out Pleiades-age stars from unrelated background stars. We find that the Pleiades constitutes the bound core of a much larger, dissolving structure that contains multiple known clusters distributed over 600 pc which we call the Greater Pleiades Complex.
Stellar Rotation and Structure of the alpha Persei Complex: When Does Gyrochronology Start to Work?
Stellar rotation can be used to determine stellar ages (gyrochronology), but it's unclear how old a star needs to be for stellar rotation be applicable as an age indicator. Here, we show that gyrochronology is applicable for stars as young as 80 Myr and show that the alpha Persei open cluster as part of a much larger, extended alpha Persei complex.