Speaker
Description
High-resolution transmission spectroscopy has opened new avenues in which to characterise the atmospheres of exoplanets. This technique has been used to unambiguously identify chemical species, map longitudinal variations in their abundance across the morning and evening limbs, as well as to infer atmospheric dynamics. We present multiple high-resolution transmission spectroscopy observations of the ultra-hot Jupiter WASP-121b, using the ESPRESSO spectrograph at the VLT, across which we consistently constrain the relative abundances of various neutral metals in its atmosphere. This is done via the cross-correlation technique, in which our observations are cross-correlated with Doppler shifted model transmission spectra. This cross-correlation value is then “mapped” to a likelihood value, which can then be folded into a Bayesian retrieval framework. From these retrievals, we can constrain atmospheric properties such as a species volume mixing ratio, the vertical T-P profile of the atmosphere, and atmospheric dynamic parameters which are then used to infer the planet’s orbital velocity, as well as offsets caused by winds and rotation. By constraining the relative abundance of species in a planet’s atmosphere, we can determine the planet’s bulk composition, and ultimately infer the planet’s formation and evolution mechanisms.
