Possibility of concentration of nonvolatile species near the surface of comet 67P/Churyumov-GerasimenkoT. Suzuki, Y. Shinnaka, L. Majumdar, T. Shibata, Y. Shibaike, H. Nomura and H. MinamotoA&A, 645 (2021) A134DOI: https://doi.org/10.1051/0004-6361/202038491