The role of phyllosilicates in shaping the Galilean moons' density gradient

<p>A key feature among the Galilean satellites is their monotonic decrease in density, indicating an ice fraction that is zero in the innermost moon Io, and about half in the outer moons Ganymede and Callisto. So far, there is no formation scenario that explains this gradient while considering the moons grew in a water-depleted circumplanetary disk. Here, we investigate the possibility that the jovian circumplanetary disk was fueled with ice-free chondritic minerals, including phyllosilicates. To do so,&#160;we use a standard one-dimensional gas-starved accretion disk model derived from the literature [1, 2] coupled with gas and solids transport modules [3, 4] to investigate the evolution of vapors released by the dehydration of phyllosilicates.&#160;We show that the dehydration of such particles and the outward diffusion of the released water vapor allows condensation of significant amounts of ice in the formation region of Ganymede and Callisto in the Jovian circumplanetary disk. This mechanism naturally explains the presence of ice-rich moons around a water-depleted Jupiter.</p> <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>[1] Canup, R.M., Ward, W.R. 2002. Formation of the Galilean Satellites: Conditions of Accretion. The Astronomical Journal 124, 3404&#8211;3423. doi:10.1086/344684</p> <p>[2] Sasaki, T., Stewart, G.R., Ida, S. 2010. Origin of the Different Architectures of the Jovian and Saturnian Satellite Systems. The Astrophysical Journal 714, 1052&#8211;1064. doi:10.1088/0004-637X/714/2/1052</p> <p>[3] Birnstiel, T., Klahr, H., Ercolano, B. 2012. A simple model for the evolution of the dust population in protoplanetary disks. Astronomy and Astrophysics 539. doi:10.1051/0004-6361/201118136</p> <p>[4] Anderson, S.E., Mousis, O., Ronnet, T. 2021. Formation Conditions of Titan's and Enceladus's Building Blocks in Saturn's Circumplanetary Disk. The Planetary Science Journal 2. doi:10.3847/PSJ/abe0ba</p> </div> </div> </div>