The Specific Heat of Astro-materials: Review of Theoretical Concepts, Materials, and Techniques

Abstract

We provide detailed background, theoretical and practical, on the specific heat of minerals and mixtures thereof, ‘astro-materials,’ as well as background information on common minerals and other relevant solid substances found on the surfaces of solar system bodies. Furthermore, we demonstrate how to use specific heat and composition data for lunar samples and meteorites as well as a new database of endmember mineral heat capacities (the result of an extensive literature review) to construct reference models for the isobaric specific heat cP as a function of temperature for common solar system materials. Using a (generally linear) mixing model for the specific heat of minerals allows extrapolation of the available data to very low and very high temperatures, such that models cover the temperature range between 10 K and 1000 K at least (and pressures from zero up to several kbars). We describe a procedure to estimate cP(T) for virtually any solid solar system material with a known mineral composition, e.g., model specific heat as a function of temperature for a number of typical meteorite classes with known mineralogical compositions. We present, as examples, the cP(T) curves of a number of well-described laboratory regolith analogs, as well as for planetary ices and ‘tholins’ in the outer solar system. Part II will review and present the heat capacity database for minerals and compounds and part III is going to cover applications, standard reference compositions, cP(T) curves, and a comparison with new and literature experimental data.

Strong magnetoelastic coupling in MnCoSi compounds studied in pulsed magnetic fields

“…It is expected that the stabilization of the chemical driving force occurs in the temperature range where the density of thermally excited phonons is strongly reduced. According to the Debye model [54], the specific heat C p versus temperature shows a maximum slope around 0.28θ D , where θ D is the Debye temperature [54,55]. For MnCoSi and related derivatives θ D is between 375 and 385 K [56,57], resulting in a maximum slope around 100 K. For temperatures below 0.1θ D (about 40 K), the amount of thermally excited phonons is very low, which is consistent with our experimental observation (no transition).…”

Semi-implicit Solver for the Heat Equation with Stefan–Boltzmann Law Boundary Condition

“…In the terrestrial context, Robertson (1988) provides an extensive compilation of thermal properties of bulk rock. For the heat capacity of silicates as a function of temperature see Winter & Saari (1969) and Biele et al (2022). Notably, many silicates have about the same specific heat capacity.…”

Dust Coagulation Reconciles Protoplanetary Disk Observations with the Vertical Shear Instability. I. Dust Coagulation and the VSI Dead Zone

“…with the dust-to-gas density ratio ρ d /ρ g = ε and the specific heat capacity of the dust particles C d . As a typical value we pick C d = 800 J kg −1 K −1 , as used by Barranco et al (2018;see Wasson 1974;Piqueux et al 2021;Biele et al 2022). If the collisional coupling is efficient, i.e., temperature perturbations in the gas are transferred to the dust, the thermal equilibrium of the grains will be restored by the emission of radiation.…”