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The chemical composition of a planet’s atmosphere is intimately tied to the volatile inventory of the protoplanetary disk in which it forms. Establishing this connection requires detailed measurements of elemental abundances in disks at small spatial scales relevant to planet formation. In this talk, I will present two targeted studies of well-known Herbig Ae/Be systems, combining ALMA observations with chemical modelling to probe disk chemistry. In HD 100546 , we detect complex molecular asymmetries, interpreted as the result of shadowing from planet-induced structures within the inner cavity, generating azimuthal temperature variations that drive chemical diversity. In HD 169142 , we investigate the first detection of SiS emission from a protoplanetary disk—nearly a billion times brighter than predicted under typical conditions—indicative of planet-induced shocks that release silicon from dust grains into the gas phase. These findings reveal that planet formation can significantly reshape the chemical environment of disks, with direct implications for how emerging planets accrete their atmospheres. Together, these studies emphasise the dynamic and heterogeneous nature of disk chemistry and provide new insights into the origins of the wide diversity observed in exoplanetary atmospheres.

• Speaker: Luke Keyte (UCL)
• Tuesday 06 May 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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An outstanding gap in the current planet formation theory is about the first steps of the planet formation process; namely how, when and where the initially ISM like solid dust particles grow into pebbles and planetesimals, the building blocks of planetary cores. Protoplanetary disks provide the initial conditions for the planet formation process. They are weakly magnetized accretion disks that are subject to the magnetorotational instability (MRI), one of the main magnetized processes responsible for their angular momentum transport and gas turbulence. The nonideal magnetohydrodynamic (MHD) effects prevent the MRI from operating everywhere in PPDs, leading to a complex dichotomy between MRI active regions with higher gas turbulence and non-MRI regions with lower gas turbulence. In this talk,  I will present the first numerical framework that describes the evolution of PPDs over millions of years powered by the MRI . It captures the MRI driven gas evolution via nonideal MHD calculations, which accounts for the dynamics and growth of the solid dust particles. An MRI powered mechanism that can spontaneously generate short- and long-lived pressure maxima in the PPD is unveiled. Within the long-lived pressure maxima, solid dust particles can be efficiently trapped, grow into pebbles, and reach high enough dust-to-gas mass ratios to potentially trigger the formation of planetesimals via the streaming instability. These planetesimals and pebbles can further rapidly interact to form planetary cores.

• Speaker: Timmy Delage (Imperial)
• Tuesday 29 April 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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The orbital architecture of planets in the Solar System is thought to have been set shortly after its birth. However, ancient asteroid families are highly dispersed, suggesting that perhaps the Solar System remained chaotic until later in its history. Testing this possibility requires precise dating of the collisions that should have generated such families, but planetary surfaces record little to no information from this time. The meteorite record of asteroid collisions represents a separate and more complete archive of Solar System evolution. In this project, we leveraged recent methodological advances to build an extensive record of in-situ meteorite apatite U-Pb ages, sensitive to collisions that induce parent body break-up events. Most asteroid collisions in our record occurred 4480 +/- 20 million years ago. Only highly dispersed asteroid families are potentially co-eval with our U-Pb ages, demonstrating that strong perturbations modifying the orbital eccentricities and inclinations of asteroids were still operating at 4480 Ma. This is unexpected in scenarios where the planets completed their growth and acquired their current orbits in a few Myr within the dispersal of the protoplanetary disk. Our work provides unique evidence that the asteroid belt was still in a state of dynamical chaos 80 Myr after its formation.

• Speaker: Craig Walton (ETH)
• Tuesday 18 March 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Observations of gas in exo-Kuiper belts (mostly CO) suggest it may be common in young planetary systems, potentially reshaping our understanding of the Solar System’s youth. Uranus and Neptune’s high atmospheric C/H ratios (60–80× protosolar) could trace late accretion of carbon-rich gas from a primordial Kuiper belt. We model gas release and viscous evolution in a Solar System-analog belt, quantifying gas capture by the ice giants. Using a disk model with varied initial masses (up to 50 M⊕), viscosities, and accretion efficiencies, we simulate CO release and planetary enrichment. Results show a massive belt (∼50 M⊕, similar to that considered in e.g. the Nice model) can supply sufficient CO via late accretion to explain observed C/H values. While solid accretion during formation contributes to carbon enrichment, we find that an additional late accretion may be needed to explain the very high super solar values, which aligns with gas capture from a young, gaseous Kuiper belt. This mechanism may be universal, influencing metallicity in exoplanetary giants, with observational implications for sub-Jupiter exoplanets. Our findings support a once-gas-rich Kuiper belt as a key driver of ice giant atmospheric evolution.

• Speaker: Paul Huet (Paris Observatory)
• Tuesday 11 March 2025, 13:00-14:00
• Venue: Hoyle Committee Room - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Devolatilization — depletion of volatile elements (e.g., C, O, S, Na and K) in rocky planets relative to their host stars — is a common feature that has been observed in both the Solar System and exoplanet systems. Various mechanisms have been proposed to explain this common feature, ranging from incomplete condensation of dust materials from an ultra-hot nebula with a host stellar composition, partial evaporation of planetesimals by collisional kinetic energy and/or short-lived radiogenic heating, and vaporization of rock-forming volatiles by giant impacts. While summarizing historical data and understandings of this potentially universal phenomenon of devolatilization in rocky planet formation, I will also present in this talk a novel model based on state-of-the-art pebble accretion theory, constrained by volatile depletion of Earth and Mars, that lend support to a hybrid formation scenario where the inner solar system rocky planets grow by a combination of rapid pebble accretion and a prolonged period of planetesimal accretion and giant impacts.

Extending this model to exoplanet systems, aided by disc observations with JWST and ALMA and high-precision bulk-density observations with current and near-future facilities (e.g., CARMENES , SPECULOOS, HARPS3 , and PLATO ), will help make quantitative predictions of volatile budget and bulk composition of rocky exoplanets. The outcome will provide an important testbed for evaluating rocky exoplanetary habitability, together with unprecedented atmospheric observations with JWST and upcoming ELT . It will further provide guidance on target selections for next-generation space missions dedicated to searching for habitable worlds and exo-life signals (e.g., HWO and LIFE ).

• Speaker: Haiyang Wang (Copenhagen)
• Tuesday 04 March 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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In this talk, I will present observations and first results of six hot Jupiters with JWST NIR Spec/G395H, which are part of two JWST programmes set out to test planet formation and migration predictions. With these programmes we will measure the atmospheric metallicities and carbon-to-oxygen (C/O) ratios of a sample of misaligned and aligned hot Jupiters. All hot Jupiters must have undergone migration as they are too close to their host star to have formed in their current orbit. We further selected our sample such that the exoplanet host stars do not allow tidal orbital realignment, which means that our sample of misaligned planets have undergone high-eccentricity migration (after the disk dissipated) while our aligned targets migrated within the disk. These two different migration mechanism are predicted to result in different atmospheric composition. Hence these hot Jupiters allow us to test model predictions and shed light on the question whether we can infer migration scenarios from atmospheric measurements. Here I will present our transmission spectra of our aligned and misaligned hot Jupiters, show preliminary results and discuss current limitations when it comes to comparing C/O ratio and metallicity with predictions from planet formation and migration models.

• Speaker: Eva-Maria Ahrer (MPIA)
• Tuesday 25 February 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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The discovery and characterization of exoplanets around ultracool dwarfs require precise ground-based observations across visible and infrared wavelengths. In this talk, I will present the discovery of TOI -2407b, a Neptune-sized planet located in the Neptune desert—a sparsely populated region of parameter space for close-in exoplanets. This detection was made using SPIRIT , a novel infrared CMOS detector designed to enhance sensitivity to cool stars. I will discuss the role of SPIRIT in improving exoplanet transit observations, the development of its data pipeline, and the implications of TOI -2407b for our understanding of planet formation and evolution in the Neptune desert.

• Speaker: Clàudia Jano Muñoz (Cavendish)
• Tuesday 18 February 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Abstract not available

• Speaker: Paul Huet (Paris Observatory)
• Tuesday 11 March 2025, 13:00-14:00
• Venue: Hoyle Committee Room - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Over the past thirty years, astronomers have made extraordinary progress in detecting planets around other stars. We now know that stars commonly host planets with a wider range of physical properties and system architectures than exist in our own solar system, and that planets likely outnumber stars in our galactic neighborhood. Now, planet detection and characterization technologies have advanced to the point that it should be possible to search for signs of life in the atmospheres of Earth-like exoplanets around Sun-like stars within a few decades. These observations will give us our first glimpse at how common—or rare—life is in the universe. However, before we can carry out these observations and understand the implications for the abundance of life outside the Solar system, we must first find the nearest habitable planets to observe, learn their detailed properties, and refine our understanding of habitability. In this talk, I will describe my group’s work to fill in these knowledge gaps by developing new tools and methods to detect and characterize exoplanets. First, I will show how cutting-edge machine learning methods could help reveal the closest potentially habitable planets to Earth—ideal for biosignature searches in the 2040s. Next, I will show how we can learn about extrasolar geochemistry by studying planetary accretion onto white dwarf stars—allowing us to see whether geological processes important for habitability on Earth take place in other systems. And finally, I will describe our work to understand what happens to planets when stars run out of nuclear fuel and find out whether life can continue in a system after the host star’s death.

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• Speaker: Prof. Andrew Vanderburg, Massachusetts Institute of Technology
• Wednesday 12 February 2025, 10:00-11:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr. Mariona Badenas Agusti.

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Over the past thirty years, astronomers have made extraordinary progress in detecting planets around other stars. We now know that stars commonly host planets with a wider range of physical properties and system architectures than exist in our own solar system, and that planets likely outnumber stars in our galactic neighborhood. Now, planet detection and characterization technologies have advanced to the point that it should be possible to search for signs of life in the atmospheres of Earth-like exoplanets around Sun-like stars within a few decades. These observations will give us our first glimpse at how common—or rare—life is in the universe. However, before we can carry out these observations and understand the implications for the abundance of life outside the Solar system, we must first find the nearest habitable planets to observe, learn their detailed properties, and refine our understanding of habitability. In this talk, I will describe my group’s work to fill in these knowledge gaps by developing new tools and methods to detect and characterize exoplanets. First, I will show how cutting-edge machine learning methods could help reveal the closest potentially habitable planets to Earth—ideal for biosignature searches in the 2040s. Next, I will show how we can learn about extrasolar geochemistry by studying planetary accretion onto white dwarf stars—allowing us to see whether geological processes important for habitability on Earth take place in other systems. And finally, I will describe our work to understand what happens to planets when stars run out of nuclear fuel and find out whether life can continue in a system after the host star’s death.

• Speaker: Prof. Andrew Vanderburg, Massachusetts Institute of Technology
• Wednesday 12 February 2025, 10:00-11:00
• Venue: Hoyle Committee Room - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Mariona Badenas Agusti.

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Over the past thirty years, astronomers have made extraordinary progress in detecting planets around other stars. We now know that stars commonly host planets with a wider range of physical properties and system architectures than exist in our own solar system, and that planets likely outnumber stars in our galactic neighborhood. Now, planet detection and characterization technologies have advanced to the point that it should be possible to search for signs of life in the atmospheres of Earth-like exoplanets around Sun-like stars within a few decades. These observations will give us our first glimpse at how common—or rare—life is in the universe. However, before we can carry out these observations and understand the implications for the abundance of life outside the Solar system, we must first find the nearest habitable planets to observe, learn their detailed properties, and refine our understanding of habitability. In this talk, I will describe my group’s work to fill in these knowledge gaps by developing new tools and methods to detect and characterize exoplanets. First, I will show how cutting-edge machine learning methods could help reveal the closest potentially habitable planets to Earth—ideal for biosignature searches in the 2040s. Next, I will show how we can learn about extrasolar geochemistry by studying planetary accretion onto white dwarf stars—allowing us to see whether geological processes important for habitability on Earth take place in other systems. And finally, I will describe our work to understand what happens to planets when stars run out of nuclear fuel and find out whether life can continue in a system after the host star’s death.

• Speaker: Andrew Vanderburg, Massachusetts Institute of Technology
• Wednesday 12 February 2025, 10:00-11:00
• Venue: Hoyle Committee Room - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Mariona Badenas Agusti.

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Host stars play a huge role in shaping the planetary systems they host, both through their evolution and through the influence they have over planet formation. While the exact processes through which stars influence their planetary systems remain unclear, these processes are all expected to imprint signatures on the overall population of planets that exist throughout the galaxy. The all sky coverage of the TESS mission provides enables us to study these populations and uncover the influence of the star. In this talk I will discuss how I use the TESS Full-Frame-Image light curves to measure the occurrence rates of different planets and planetary systems, and what these occurrence rates can teach us about the impact of the host star on planet formation and evolution. In particular I will present the results from studying two populations. The first is the population of giant planets around low-mass stars, through which we can probe an extreme of giant planet formation. The second is the population of giant planets around post-main sequence stars. By studying this population we can better understand the impact of the early stages of post-main sequence stellar evolution on close-in planets, including strong tidal interactions and rapid orbital decay.

• Speaker: Ed Bryant (UCL)
• Tuesday 04 February 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Discerning patterns and trends in the physical properties of exoplanets is now possible thanks to the growing number of planet discoveries. In particular, TESS has been instrumental in adding to the sample with the detection of over 7000 potential planets, of which nearly 600 have been confirmed in the last 7 years. The distinct subpopulations that have emerged from grouping planets in different parameter spaces are now being tested against formation and evolution theories. Linking the two is still proving challenging in some cases, highlighting the need either to revise the current theories or, for rare planets, to increase the statistical sample. In this talk, I will discuss the efforts to validate TESS planet candidates with the TRAPPIST , SPECULOOS, and ASTEP ground-based facilities, focusing on small and giant planets orbiting M dwarfs. I will then present some of our most impressive results, including the discovery and study of the TOI -4336 A system, and the first confirmed planets from the MANGOS programme.

• Speaker: Mathilde Timmermans (Birmingham)
• Tuesday 28 January 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Abstract not available

• Speaker: Timothy Hallatt (MIT)
• Tuesday 17 June 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Abstract not available

• Speaker: Felix Sainsbury-Martinez (Leeds)
• Tuesday 10 June 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Abstract not available

• Speaker: Anibal Sierra (UCL)
• Tuesday 03 June 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Abstract not available

• Speaker: Lev Tal-Or (Ariel)
• Tuesday 20 May 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Abstract not available

• Speaker: Olja Panic (Leeds)
• Tuesday 13 May 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Abstract not available

• Speaker: Craig Walton (ETH)
• Tuesday 18 March 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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Abstract not available

• Speaker: Paul Huet (Paris Observatory)
• Tuesday 11 March 2025, 13:00-14:00
• Venue: Ryle seminar room + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.

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