A Search For Magnetic Hot Subdwarfs In SDSS And LAMOST
Laura Cediel, Matti Dorsch, Stephan Geier
Hot subdwarfs are helium burning stars with thin or no hydrogen envelopes. Many of them are thought to be formed by mergers involving He-core WDs, but their expected magnetic fields formed in the process have long eluded detection. In this project we searched for new magnetic hot subdwarfs in the SDSS DR17 and LAMOST DR8 catalogues. Synthetic spectra including linear Zeeman splitting were used to derive upper limits on the magnetic field strengths, identify magnetic candidates, and derive atmospheric parameters. Four stars were identified as good candidates for magnetic fields greater than 150 kG. Next to Zeeman splitting, we also searched for a newly discovered broad spectral feature at 4630Å that seems to be present in all magnetic hot subdwarfs. Finally, for stars with multiple spectra, we studied the variation of their atmospheric parameters in time - from their possible magnetic field strengths to effective temperatures and surface gravities.