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Young transiting exoplanets (< 100 Myr) provide crucial insight intoatmospheric evolution via photoevaporation. However, transmission spectroscopymeasurements to determine atmospheric composition and mass loss are challengingdue to the activity and prominent stellar disk inhomogeneities present on youngstars. We observed a full transit of V1298 Tau c, a 23 Myr, 5.59$R_\oplus$planet orbiting a young K0-K1.5 solar analogue with GRACES on Gemini-North. Wewere able to measure the Doppler tomographic signal of V1298 Tau c using the CaII infrared triplet (IRT) and find a projected obliquity of $\lambda = 5^\circ\pm 15^\circ$. The tomographic signal is only seen in the chromosphericallydriven core of the Ca II IRT, which may be the result of star-planetinteractions. Additionally, we find that excess absorption of the H-alpha linedecreases smoothly during the transit. While this could be a tentativedetection of hot gas escaping the planet, we find this variation is consistentwith similar timescale observations of other young stars that lack transitingplanets over similar timescales. We show this variation can also be explainedby the presence of starspots with surrounding facular regions. Moreobservations both in- and out-of the transits of V1298 Tau c are required todetermine the nature of the Ca II IRT and H-alpha line variations.

H-alpha and Ca II Infrared Triplet Variations During a Transit of the 23 Myr Planet V1298 Tau c