The refractory-to-ice mass ratio in comets. Issue 3 (30th October 2018)

• Record Type: Journal Article
• Authors: Fulle, Marco; Blum, J; Green, S F; Gundlach, B; Herique, A; Moreno, F; Mottola, S; Rotundi, A; Snodgrass, C
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 482:Issue 3(2019)
• Page Start: 3326
• Page End: 3340
• Publication Date: 2018-10-30
• Subjects: space vehicles -- comets: general -- comets: individual: 67P/Churyumov–Gerasimenko -- Kuiper belt: general -- protoplanetary discs; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty2926
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We review the complex relationship between the dust-to-gas mass ratio usually estimated in the material lost by comets, and the refractory-to-ice mass ratio inside the nucleus, which constrains the origin of comets. Such a relationship is dominated by the mass transfer from the perihelion erosion to fallout over most of the nucleus surface. This makes the refractory-to-ice mass ratio inside the nucleus up to 10 times larger than the dust-to-gas mass ratio in the lost material, because the lost material is missing most of the refractories which were inside the pristine nucleus before the erosion. We review the refractory-to-ice mass ratios available for the comet nuclei visited by space missions, and for the Kuiper Belt Objects with well-defined bulk density, finding the 1-σ lower limit of 3. Therefore, comets and KBOs may have less water than CI-chondrites, as predicted by models of comet formation by the gravitational collapse of cm-sized pebbles driven by streaming instabilities in the protoplanetary disc.