Observation of the Molecular Zeeman Effect in the G band.pdfVIP

Observation of the Molecular Zeeman Effect in the G band 1 1,2 3,4 1,5 6 A. Asensio Ramos , J. Trujillo Bueno , M. Bianda , R. Manso Sainz , H. Uitenbroek ABSTRACT 4 Here we report on the first observational investigation of the Zeeman effect 0 ˚ in the G band around 4305 A. Our spectropolarimetric observations of sunspots 0 2 with the Z¨urich Imaging Polarimeter at the IRSOL facility confirm our previ- l ous theoretical prediction that the molecular Zeeman effect produces measurable u J circular polarization signatures in several CH lines that are not overlapped with 6 atomic transitions. We also find both circular and linear polarization signals 1 produced by atomic lines whose wavelengths lie in the G band spectral region. 1 Together, such molecular and atomic lines are potentially important for empir- v 2 ical investigations on solar and stellar magnetism. For instance, a comparison 3 3 between observed and calculated Stokes profiles suggests that the thermodynami- 7 cal and/or magnetic properties of the photospheric regions of sunspot umbrae are 0 4 horizontally structured with a component that might be associated with umbral 0 dots. / h p - Subject headings: polarization — molecular data — radiative transfer — Sun: o r magnetic fields t s a : v i X 1. Introduction r a ˚ The Fraunhofer G band around 4305 A include