The magnetic fields of exoplanet hostM-dwarf stars : The magnetic fields of exoplanet hostM-dwarf stars

• Main Author: Herard, Thomas
• Format: Bachelor Thesis
• Language: English
• Published: Uppsala universitet, Teoretisk astrofysik 2021
• Subjects: Astronomy; Astrophysics and Cosmology; Astronomi; astrofysik och kosmologi; Milky Way; narval
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-455262

The majority of stars in the Milky Way are M dwarfs whichmake up 75 % of stars in the vicinity of the sun. As the magneticfield of stars can significantly affect the interiors and theatmospheres of the exoplanets they host within the stellar system,characterising this magnetic field is of major importance.In this work, we selected a sample of 23 exoplanet hostM dwarfs and analysed the observations made by the highresolutionspectropolarimeters ESPaDOnS and NARVAL availablein PolarBase for these stars. In particular, we used theLSD Stokes I and V spectra to measure the projection alongthe line of sight of the average magnetic field over the stellarsurface. 60% of stars had a likely magnetic signatures with adetection greater than 2. By taking the maximum value foreach star over the different observations, the median magneticfield strength measured was 55 G and only a few stars exceeded100 G in strength.