Probing exoplanetary magnetism via atomic alignment effect

ABSTRACT The intrinsic MFs of exoplanets affect the structure of their atmospheres and plasma spheres and, therefore, the observational manifestations of transit absorptions. This work proposes a new method for constraining the presence or absence of relatively weak MFs. The method is based on the quantum effect of atomic alignment of the lower energy level resulting in changing the absorption probabilities of individual transitions of multiplets from the equilibrium 2J + 1 value. It appears to be sensitive to fields above ∼0.001 G. We applied this method to some available transit observations of exoplanets and demonstrate that we indeed have the possibility to constrain the intrinsic MF of some exoplanets right now. However, more precise and repetitive measurements, which might be available in near future, are needed for definite conclusions.