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Séminaire du Jeudi 8 septembre 2016

Mapping the surfaces of stars and unveiling planets

Gaitee Hussain (ESO)
Thursday September 8th - 11am
IRAM Seminar Room - IPAG

Solar-type stars display signs of magnetic activity at all wavelengths, from energetic X-ray and UV flares to photometric variability caused by large cool spots. The rotation rate, internal structure and age of a main sequence star control critical aspects of its magnetic behaviour. For pre-main sequence stars however these trends are harder to find — these systems are particularly interesting as this is when the bulk of planet formation is likely to occur.

Over the past two decades techniques based on medical imaging principles have enabled us to map the large scale fields on stars covering a range of evolutionary states. I will summarise our findings for young stars and show how our maps can be used to substantially reduce “jitter” in radial velocity measurements ; unveiling the presence of one of the youngest exoplanets. Using our stellar surface maps we can therefore (a) map active regions on stars and obtain key dynamo parameters ; (b) discover close-in planets ; and (c) model the stellar winds and circumstellar/interplanetary environments in which planetary systems evolve. I will conclude by showing some of the latest 3D MHD models of young planet-hosting stars and the latest efforts to calibrate them against EUV and X-ray observations.

Sous la tutelle de:


Sous la tutelle de:

CNRS Université Grenoble Alpes