When Growing Giants Push Back, How Gas Accretion Drives Planets Outward
Ida and collaborators show that gas-accreting giant planets can migrate outward rather than inward, thanks to an asymmetry in gas flow around the planet created during accretion. This effect occurs only when the planet opens a moderate-depth gap in the disk, captured by the range (0.03 <= K' <= 50). The authors develop a semi-analytical formula describing this behavior and demonstrate that such outward migration helps explain why many gas giants are found beyond 1 au.
How Giant Planets Collect Their Metals: A New Look at the Mass-Metallicity Relation
Chachan et al. analyze 147 giant exoplanets to refine the mass–metallicity relation. They find that smaller planets are metal-rich, while metallicity decreases with mass but flattens at about seven times solar. This suggests that giant planets continue to accrete heavy elements even during gas accretion, delaying runaway growth until 30–60 Earth masses and challenging classical formation models.
Is the Sun Really That Special? A Closer Look at Its Chemical Makeup
Carlos et al. studied 50 Sun-like stars to investigate whether the Sun's unusual chemical makeup is due to its planets. They found no strong link between giant planets and the Sun’s low refractory element content. Instead, the differences are better explained by the Galaxy’s chemical evolution. The Sun is slightly unusual, but not uniquely so.