Precise determination of circumstellar disk lifetimes

Determining the lifetime of a circumstellar disk is key to understanding the timescales of planet formation. Typically, this is done by measuring the fraction of young stars with infrared (IR) excess, a sign of circumstellar material, in stellar clusters of different ages. However, comparing data from different star-forming regions at different distances introduces uncertainties and biases because of the different sample completeness and environment. This study addresses these challenges by analyzing 33 clusters, aged 3–21 million years (PARSEC isochrones) within the Scorpius-Centaurus OB association, sampling the stellar initial mass function (IMF) from the hydrogen-burning limit to about 8 M⊙. By using Gaia, 2MASS, and WISE data, we identified stars with IR excess through color-color diagrams and spectral energy distributions, ensuring a consistent selection of disk-bearing sources. Our results indicate a disk lifetime of 5.8 ± 0.3 Myr, about a factor of two longer than most previous estimates, suggesting that planet formation might take more time than previously thought. We also find that an exponential decay model best describes disk dispersal. These findings emphasize the importance of studying disk evolution in a single star-forming region to reduce uncertainties and refine our understanding of planet formation timescales.