Refractory elements in the gas phase for comet 67P/Churyumov-Gerasimenko

Abstract

Results. We found that gas-phase silicon was present throughout the Rosetta mission. Furthermore, the presence of sodium and iron atoms near the comet's perihelion confirms that sputtering cannot be the sole release process for refractory elements into the gas phase. Nickel was found to be below the detection limit. The search for parent species of any of the identified gas phase refractories has not been successful. Upper limits for a suite of possible fragment species (SiH, SiC, NaH, etc.) of larger parent and daughter species have been obtained. Furthermore, Si did not exhibit the same drop in signal as do common cometary gases when the spacecraft is pointed away from the nucleus. The combined results suggest that a direct release of elemental species from small grains on the surface of the nucleus or from small grains in the surrounding coma is a more likely explanation than the previous assumption of release via the dissociation of gaseous parent molecules.

Accepted for publication in A&A

References in corpus (5)

• The recent dynamical history of comet 67P/Churyumov-Gerasimenko
• Gaseous atomic nickel in the coma of interstellar comet 2I/Borisov
• First in-situ detection of the CN radical in comets and evidence for a distributed source
• FeI and NiI in cometary atmospheres. Connections between the NiI/FeI abundance ratio and chemical characteristics of Jupiter-family and Oort-cloud comets
• Detection of volatiles undergoing sublimation from 67P/Churyumov-Gerasimenko coma particles using ROSINA/COPS. I. The ram gauge