(Delrez) Probing the emission spectra of ultra-hot Jupiters using ground-based occultation photometry. (Meru) Understanding the morphology of the protoplanetary disc, Elias 2-27

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• Laetitia Delrez & Farzana Meru (Cambridge)
• Wednesday 01 March 2017, 16:00-17:00
• Martin Ryle Seminar Room, Kavli Institute.

If you have a question about this talk, please contact Ed Gillen.

(Delrez) By observing the occultation (secondary eclipse) of a transiting exoplanet by its host star in the (near-)infrared, the thermal emission of its dayside can be retrieved. Using this technique at different wavelengths in the (near-)infrared allows to probe the emission spectrum of the planet’s dayside, from which insights on the vertical thermal structure and chemical composition of its atmosphere can be gained. Very hot and inflated gas giants in very-short-period orbits around their stars are the most favourable targets for such measurements, thanks to their high temperature and large size. The atmospheres of such ultra-hot Jupiters are expected to be conducive for gaseous TiO and VO, which could cause thermal inversions (i.e. stratospheres) by reprocessing incident UV/visible irradiation to heat in the upper atmospheric layers. Thermal inversions have been previously claimed for several hot Jupiters based on Spitzer observations, but these results were recently found to suffer from significant systematic biases and were thus seriously called into question. Nevertheless, hottest planets are still the best candidates to host thermal inversions in their dayside atmospheres, the only planet showing clear evidence for a temperature inversion to date being WASP -33b, which is one of the most highly irradiated hot Jupiters currently known. In this talk, I will present results of an intense ground-based photometric campaign aiming at probing the emission spectra of WASP -103b and WASP -121b, two ultra-hot Jupiters orbiting their host stars just beyond the Roche limit.

(Meru) Recent observations of protoplanetary discs are starting to hint that the young turbulent self-gravitating disc phase is more important for planet formation than previously thought. In contrast to the standard paradigm for planet formation, these results may now have pushed the likely era of planet formation into the brief, early self-gravitating stage of disc evolution. One such example is the Elias 2-27 protoplanetary disc which exhibits strong spiral structures out to approximately 250au. Through the results of recent numerical simulations I will discuss whether Elias 2-27 could be the first observation of a self-gravitating disc.

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
• Martin Ryle Seminar Room, Kavli Institute

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