Abstract:
There is growing evidence from stellar kinematics and galactic chemical evolution suggesting that giant planets
(MP 0.3MJ) are relatively young compared to the most commonly occurring population of small planets
(MP < 0.3MJ). To further test the validity of these results, we analyzed the ages for a large number of 2336
exoplanet hosting stars determined using three different but well-established isochrone fitting models, namely,
PARSEC, MIST, and Yonsei Yale. As input parameters, we used Gaia DR3 parallaxes, magnitudes, and
photometric temperature, as well as spectroscopically determined more accurate temperatures and metallicities
from the Sweet Catalog. Our analysis suggests that ∼50%–70% of stars with planets are younger than the Sun. We
also find that, among the confirmed exoplanetary systems, stars hosting giant planets are even younger compared to
small planet hosts. The median age of ∼2.61–3.48 Gyr estimated for the giant planet-hosting stars (depending on
the model input parameters) suggests that the later chemical enrichment of the galaxy by the iron-peak elements,
largely produced from Type Ia supernovae, may have paved the way for the formation of gas giants. Furthermore,
within the giant planet population itself, stars hosting hot Jupiters (orbital period 10 days) are found to be
younger compared to the stellar hosts of cool and warm Jupiters (orbital period >10 days), implying that hot
Jupiters could be the youngest systems to emerge in the progression of planet formation.
