[12] The variable nature of this star was first observed in 1949 by Katherine C. Gordon and Gerald E. Kron at Lick Observatory.

[17] Examination of the corona in X-ray shows compact loop structures that span up to 30% of the size of the star.

[20] In 2021, a superflare on AD Leo was observed simultaneously in X-ray by XMM-Newton and in optical by TESS.

[21] During a 1943 proper motion study by Dirk Reuyl at McCormick Observatory, AD Leonis was suspected of having a companion.

[22] A 1997 search with a near-infrared speckle interferometer failed to detect a companion orbiting 1–10 AU from the star.

[26] However, subsequent studies starting in 2020 refuted the planet hypothesis, finding stellar activity to be the most likely explanation for the radial velocity variations.