ETH Exoplanets & Habitability Seminars Spring Semester 2022
Exoplanets & Habitability Seminar Spring Semester 2022
Wednesday, 1st of June, from 5 to 6pm.
Speaker
Marta L. Bryan
external page Her research
Title
Exo-Jupiters: The Movers and Shakers of Planetary Systems
Abstract
Understanding what formation processes produce the extraordinary diversity of planetary systems that we see today is one of the driving questions in the field. Of all the new planets that have been discovered, gas giants are the easiest ones for us to find – they are bigger, brighter, and more massive than any other kind of planet. This means that they are ideal targets for characterization techniques that can tell us about the planet formation process, and they are so massive that they dominate the dynamics of their systems, impacting the formation of other planets. Gas giants are an obvious place for us to start if we want to learn about the physics of planet formation.
In this talk I will describe my work using multiple observational techniques to explore the formation and evolution of gas giants. I will discuss how targeting directly imaged planets with high-resolution spectroscopy enables measurements of new planetary properties like rotation rates, obliquities, and detailed atmospheric abundances. These provide fundamental insights into the physics of gas giant formation, such as the evolution of planetary angular momentum. I will describe how leveraging high-contrast imaging techniques to look for planets in their infancy rules out gravitational scattering as the origin of wide-separation gas giants, and constrains the timing of gas giant formation and migration. I will also talk about how radial velocity and astrometry searches for Jupiter analogs in systems with known inner planets reveal the impact gas giants have on the inner architectures of planetary systems, and are a key step in the search for life on other planets. Finally, I will highlight the important role that the next generation ELTs will have in extending these high-resolution spectroscopy measurements to directly imaged ice giant and terrestrials worlds, opening new windows into their formation histories and enabling searches for biosignatures in their atmospheres.
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Wednesday, 25th of May, from 1 to 2pm.
Speaker
Paul Mollière
external page His research
Title
Retrieving the atmospheric properties of cloudy directly imaged planets
Abstract
Future direct imaging observations will start probing the actual peak of the giant planet occurrence rate at ~3 au. This will enable the study of the most common giant planet type, instead of making do with hot Jupiters, or today’s population of directly imaged companions, found at separations >~ 10 au. The atmospheric composition of gas giant planets can be extracted from their emission spectra, and is widely regarded as the key for placing constraints on their formation. Because gas giant planets dynamically dominate the process of planet formation in the systems they reside in, understanding their formation is crucial to inform planet formation in general. In my talk I will discuss our work that strives to derive the atmospheric composition of directly imaged planets using so-called free retrievals. Compared to previous analysis methods, the strength of retrievals is their model flexibility, allowing to let the observational data constrain uncertain physical processes, most importantly the formation of atmospheric clouds. I will show how current observations of cloudy planets often lead to degenerate or biased solutions when inferring atmospheric properties, and will highlight how observations of the just-launched James Webb Space Telescope (JWST) will break such degeneracies, and enable training our methods for situations where JWST data is not available. In doing so, the atmospheric composition of cloudy directly imaged planets may finally be decipherable. I will end my presentation with a summary of how atmospheric composition may actually allow constraining planet formation, and what obstacles need to be overcome.
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Wednesday, 18th of May, from 2 to 3pm
Speaker
external page Cecilia Lazzoni
Title
Looking for planetary satellites around directly imaged substellar companions.
Abstract
During the past years, the direct imaging technique has proven to be an extremely valid method to detect and characterize exoplanets. Coupling extreme adaptive optics with the 8-meters class of telescopes, we are able to push the limits of detection to planets of a few Jupiter masses for the youngest systems.
Considering the mass and, especially, the separation at which directly imaged exoplanets are revealed the latter technique is particularly suitable for the search of satellites.
In this talk we will investigate the hunting capabilities of satellites around directly imaged planets, either with direct and indirect methods.
Even if up to date the detection of classic rocky moons escapes our capabilities, with the upcoming arrival of instruments both from the ground and from space we might be able to unveil such worlds. Also, more massive satellites might be common in exoplanetary systems and much easier to detect.
I will then introduce the Negative Fake Companion Technique, developed to subtract the contribution of directly imaged exoplanets and brown dwarfs and to investigate their close surroundings for the presence of satellites. In this framework, the first candidate satellite was discovered in the DH Tau system. The latter hosts an M1 parent star, a 10 Mjup exoplanet and its candidate Jupiter-like satellite.
Systems like DH Tau open up to an entire new category of mostly unknown planetary architecture, the "binary planets".
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Wednesday, 11th of May, from 4 to 5pm.
Speaker
external page Jean-Baptiste Ruffio
Title
Probing exoplanet formation from novel high-resolution spectroscopy techniques
Abstract
I will discuss various efforts to better constrain the formation history of planetary systems from direct imaging surveys and high-resolution spectroscopy. Planet formation can be studied from planet occurrence rates, population-level statistics of dynamical or atmospheric parameters, or even direct observations of accreting exoplanets. A particularly exciting prospect for high-contrast imaging has been the development of dedicated infrared high-resolution spectroscopic facilities. I will discuss our different efforts to build libraries of moderate to high-resolution spectra of low mass companions and show the results of a uniform analysis of a decade worth of observations of the HR 8799 planets with Keck/OSIRIS. This includes the measurement of their carbon-to-oxygen ratio, which is a possible tracer of a planet's accretion history. We are also demonstrating the power of high-resolution integral field spectroscopy to detect planets at very small separations with a pathfinder survey of nearby star forming regions with Keck/OSIRIS. Finally, I will highlight the first science results and future developments of the Keck Planet Imager and Characterizer (KPIC) mounted on Keck 2, which is enabling R~35,000 spectroscopy of the highest contrast known companions. This includes early efforts to look for exomoons by measuring the wobble of directly imaged planets caused by orbiting satellites with planetary radial velocity surveys.