Magnetic Fields on Low Mass Ultra Fast Rotators using TESS and FORS2

Lauren Doyle, Gavin Ramsay, Stefano Bagnulo, Gerry Doyle
2021 Zenodo  
We identify a small group of low mass ultra fast rotating (UFR) stars which have rotation periods less than 0.3 days and show low levels of flaring activity in their TESS lightcurves. Given the rotation-activity relation, faster rotating stars should display higher levels of activity. We do not find any evidence that the lack of activity is related to age or rotational velocities and conclude it is most likely to be a result of the magnetic configurations of the star. In this talk, we will
more » ... ss the further analysis of these UFRs using TESS data from Cycles 1-3, NOT spectra and FORS2 spectropolarimetric observations. Overall, we compare the flare rates between the TESS Cycle lightcurves while investigating any long term variability. The NOT spectra is used to investigate radial velocity variations ruling out potential short duration binaries. We also bring in the spectropolarimetric data to determine an estimate on the magnetic field strength of our targets. If these objects do possess a strong magnetic field then why do they not show more flares? Also, If they do not possess a strong field then how can such rapidly rotating stars not show evidence for a magnetic field?
doi:10.5281/zenodo.5128900 fatcat:qk4ppj3rgfa5ve3s4bbv4f4bz4