Deciphering giant planet formation

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• Olja Panic (Leeds)
• Tuesday 13 May 2025, 13:00-14:00
• Ryle seminar room + ONLINE - Details to be sent by email.

If you have a question about this talk, please contact Dr Dolev Bashi.

The multitude of detected exoplanets and their diversity never cease to fascinate us, while the statistical trends emerging from these detections present promising opportunities to delve into the past of planetary systems, all the way back to their formation. In this talk, I will give an overview of my group’s recent observational and theoretical results on the formation of gas giants. Owing to their large gravitational influence these planets cannot be overlooked in the evolution of planetary systems towards a life-harbouring system such as our own. Results of RV and direct imaging surveys in recent years revealed that gas giants are not a common outcome of planet formation, and that their most frequent hosts – the intermediate-mass stars (IMSs) seem to hold the answers to their formation.

We investigate the formation of giant planets using the pebble-accretion driven planet formation simulations, exploring a range of different formation conditions. In this work, and in contrast to common approaches in the literature, we implement stellar-mass dependent time evolution of luminosity on the pre-main sequence, and find that this makes a significant difference to giant planet formation outcomes. We successfully reproduce the giant planet occurrence rates as a function of stellar mass, found by RV surveys. This work revealed that mass accretion rate is the key parameter in determining whether a star will likely host a giant planet in its future planetary system.

Our large surveys of pre-main sequence star candidates led to the first unbiased sample of such IMSs, and the result that their protoplanetary discs are dispersed faster than discs around low mass stars, a devastating prospect for giant planet formation unless it happens very fast (e.g., via GI). This is in stark contrast with the observational examples of massive discs actively forming planets at 5-6Myr of age. Our work shows that late gas accretion, as seen in some of those sources, must be the dominant mechanism that sustains the mass reservoir of these older protoplanetary discs. Our surveys, and follow-up with ALMA also allowed a unique insight in the elusive transition state from protoplanetary to debris discs and origin of gas in debris discs.

This talk is part of the Exoplanet Seminars series.

This talk is included in these lists:

• Cambridge Astronomy Talks
• Combined External Astrophysics Talks DAMTP
• Cosmology, Astrophysics and General Relativity
• Exoplanet Seminars
• Institute of Astronomy Talk Lists
• LCLU Departmental Talks
• Ryle seminar room + ONLINE - Details to be sent by email

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