Description:

Title: Hikes Across the Desert
Speaker: Amaury Triaud, Centre for Planetary Sciences, University of Toronto

Host: Vicky Kalogera

Abstract: Low mass stars, brown dwarfs and hot Jupiters have similar radii. For a fairly narrow size range (~0.7 to 2 Jupiter radii) Nature has produced objects covering nearly three orders of magnitude in mass (between 0.2 and 200 Jupiter masses). This is of particular importance for transit surveys which are mostly sensitive to size. Those same surveys are also heavily biased towards proximity to the central, most luminous object. This is how ground-based transit surveys have primarily found hot Jupiters. Those fascinating planets can at times be hotter and bigger than the smallest Hydrogen burning stars.

My talk will explore the transition from planet to brown dwarf, to low mass star, and how one can compare them to one another. I will show similarities, but also distinctions between these different classes of objects.

I will present the results of observations from the WASP survey including an independent and mostly unbiased confirmation of the brown dwarf desert. We also looked at the spin-orbit angle distributions, as measured from the Rossiter-McLaughlin effect, between both ends of that desert. They are very different. In addition, our observations discovered systems containing both planets and brown dwarfs that can make us wonder about their formation process.

Brown dwarfs, hot Jupiters and low mass stars have similar fluxes. I will show how colour-magnitude diagrams can be constructed to compare these objects and how they can used for observations. Their compilation unveiled a new diversity for exoplanets: they show a wider variety of atmospheric properties than their brown dwarf cousins.

Finally, I will push into the realm of circumbinary architectures, and how they can expand the discussion on the distinction between planets, brown dwarfs and low mass stars, but also how they can be exploited to study stellar and planetary formation, to investigate cold planetary atmospheres and help the search for and eventual characterisation of habitable-zone rocky worlds.

Keywords: Physics, Astronomy, Astrophysics