Context. The study of the snow line is an important topic in several domains of astrophysics, and particularly for the evolution of proto-stellar environments and the formation of planets. Aims. The formation of the first layer of ice on carbon grains requires low temperatures compared to the temperature of evaporation (T > 100 K). This asymmetry generates a zone in which bare and icy dust grains coexist. Methods. We use Monte-Carlo simulations to describe the formation time scales of ice mantles on bare grains in protostellar disks and massive protostars environments. Then we analytically describe these two systems in terms of grain populations subject to infall and turbulence, and assume steady-state. Results. Our results show that there is an extended region beyond the snow line where icy and bare grains can coexist, in both proto-planetary disks and massive protostars. This zone is not negligible compared to the total size of the objects: on the order of 0.4 AU for proto-planetary disks and 5400 AU for high-mass protostars. Times to reach the steady-state are respectively es- timated from 10^2 to 10^5 yr. Conclusions. The presence of a zone, a so-called snow border, in which bare and icy grains co- exist can have a major impact on our knowledge of protostellar environments. From a theoretical point of view, the progression of icy grains to bare grains as the temperature increases, could be a realistic way to model hot cores and hot corinos. Also, in this zone, the formation of planetesimals will require the coagulation of bare and icy grains. Observationally, this zone allows high abundances of gas phase species at large scales, for massive protostars particularly, even at low temperatures (down to 50 K).
Collisional Growth of Icy Dust Aggregates in Disk Formation Stage: Difficulties for Planetesimal Formation via Direct Collisional Growth outside the Snowline
Formation of Ryugu's parent planetesimal beyond the CO$_{2}$ snow line from small pebbles: insights from thermal evolution modeling
Japan Agency for Marine-Earth Science and Technology（日本海洋地球科学技术局）；Earth-Life Science Institute, Institute of Science Tokyo（东京科学研究所生命理工学研究院）；Department of Earth and Planetary Sciences, Hokkaido University（北海道大学地球行星科学系）；Faculty of Science, Ibaraki University（茨城大学理学部）；School of Science, Institute of Science Tokyo（东京科学研究所理学院）；Department of Earth, Atmospheric, and Planetary Sciences, Purdue University（普渡大学地球大气与行星科学系）
Europa smooth plains formation: a SPH cryovolcanic model
Laboratoire Environnements et Atmosphères Terrestres et Planétaires, Université de Reims Champagne-Ardenne（地球与行星大气与环境实验室，兰斯香槟-阿登大学）；Laboratoire de Planétologie et Géodynamique, CNRS UMR 6112, Université de Nantes（行星学与地球动力学实验室，法国国家科学研究中心联合研究单位6112，南特大学）；Jet Propulsion Laboratory, California Institute of Technology（喷气推进实验室，加州理工学院）
