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On the AGB, low to intermediate mass stars blow away their outer envelopes,forming planetary nebulae. Interaction between the planetary nebula and itscentral progenitor is poorly understood and even more complex when the centralobject is a binary star with a magnetically active component, like it is thecase for IN Com. We aim to quantify the surface activity of the cool binarycomponent of IN Com and aim to explain its origin. We need a betterunderstanding of how central binary stars in planetary nebulae evolve and howthis evolution could develop such magnetically active stars like IN Com. Wepresent 13 Doppler images covering six months in 2017 and use them to measurethe surface differential rotation. Hitherto unpublished photometric data frombetween 1989-2017 are presented. We apply Fourier-transformation to bothphotometry and spectra. Very high resolution spectra are used to update INCom's astrophysical parameters by means of spectral synthesis. Doppler imagesshow cool and warm spots coexisting with an average surface temperaturecontrast of -1000K and +300K with respect to the effective temperature.Approximately 8% of the surface is covered with cool spots and 3% with warmspots. A cool polar spot is seen in all images. We found anti-solar surfacedifferential rotation with a shear coefficient of -0.026+/-0.005 and anequatorial rotation period of 5.973+/-0.008 d. We reconfirm the 5.9-dayrotation period of the cool star from photometry, radial velocities, and Halpha line-profile variations. A long-term V-brightness variation with a likelyperiod of 7.2yr is found. It appears in phase with the orbital radial velocityof the binary system in the sense brightest at highest velocity and faintest atlowest velocity. We redetermine [Ba/Fe], [Y/Fe] and [Sr/Fe] ratios and confirmthe overabundance of these s-process elements in the atmosphere of IN Com.

Surface magnetic activity of the fast-rotating G5-giant IN Comae, central star of the faint planetary nebula LoTr 5