Dr. Carolina Villarreal D’Angelo

Trinity College Dublin, Ireland

The use of Lyman alpha observations to constrain stellar and planetary winds properties

Abstract : The amount of high energy irradiation that gaseous planets orbiting very close to their star receive can cause the heating and expansion of their upper atmospheric layers. If the planetary atmosphere is heated enough, the gas can become gravitationally unbound from the planet and escape in the form of a wind. The wind of these particular exoplanets will interact with the wind from their host star creating signatures that can be observed.
Atmospheric escape has been detected for a couple of hot-Jupiters and warm-Neptunes by means of in-transit spectroscopy observations carried in Lyman alpha line. These observations then become a tool to constrain the properties of the planetary and stellar wind using numerical simulations.
In this seminar, I will describe the observations that led to the discover of escaping material from the atmosphere of hot-Jupiters and introduce the theory of photoevaporation in planetary atmospheres.  I will explain the numerical tools that help us to model these systems and how we can use them to constrain the characteristics of the stellar wind or the presence of a planetary magnetic field, among other system parameters. I will present the results from the numerical modelling of two well-known exoplanetary systems: HD209458b and GJ436b I have carried out so far.