Time-Varying Potassium in High-Resolution Spectra of the Type Ia   Supernova 2014J
  We present a time series of the highest resolution spectra yet published for the nearby Type Ia supernova (SN) 2014J in M82. They were obtained at 11 epochs over 33 days around peak brightness with the Levy Spectrograph (resolution R~110,000) on the 2.4m Automated Planet Finder telescope at Lick Observatory. We identify multiple Na I D and K I absorption features, as well as absorption by Ca I H & K and several of the more common diffuse interstellar bands (DIBs). We see no evolution in any component of Na I D, Ca I, or in the DIBs, but do establish the dissipation/weakening of the two most blueshifted components of K I. We present several potential physical explanations, finding the most plausible to be photoionization of circumstellar material, and discuss the implications of our results with respect to the progenitor scenario of SN 2014J. 
M.L. Graham, S. Valenti, B.J. Fulton, L.M. Weiss, K.J. Shen, P.L.   Kelly, W. Zheng, A.V. Filippenko, G.W. Marcy, D.A. Howel...
astro-ph.SR astro-ph.CO