BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:Isotope ratios in transiting and directly-imaged exoplanetary atmo spheres - Siddharth Gandhi (Warwick) DTSTART:20241008T101500Z DTEND:20241008T110000Z UID:TALK221803@talks.cam.ac.uk CONTACT:David Buscher DESCRIPTION:Atmospheric abundances play an important role in planetary phy sics\, allowing us to probe the formation mechanisms of exoplanets through bulk constraints on metallicity and carbon-to-oxygen ratios. Recently how ever\, we have been able to constrain isotope ratios in exoplanetary atmos pheres\, both for transiting and directly-imaged companions. These add an extra dimension to probe formation processes\, as well as providing insigh ts into interstellar chemistry. While carbon isotope ratios are broadly co nsistent across the Solar System\, in molecular clouds and protoplanetary disks\, carbon isotope ratios can be altered by gas/ice partitioning\, iso topic ion-exchange reactions and isotope-selective photodissociation. Henc e we can obtain a great deal of insight into the planet's history through studying the isotopic ratio. In this talk I will discuss the results from two directly-imaged companions\, VHS 1256 b and AB Pictoris b\, which show differences in the 12/13C ratios in their atmospheres from observations w ith JWST and VLT respectively. I will compare and contrast these isotope r atios to the Solar System\, transiting exoplanets as well as other directl y-imaged targets and field brown dwarfs\, to understand their formation hi stories. I will also delve into the oxygen isotope ratio constraints that we are able to constrain for VHS 1256 b\, and the variability that we see between night to night for the AB Pictoris b observations. Finally\, I wil l discuss the orbital solution of AB Pictoris b\, and the orbital obliquit y and inclination constraints that we obtain from the high resolution obse rvations. LOCATION:Coffee area\, Battcock Centre END:VEVENT END:VCALENDAR