Comet C/2013 US₁₀ (Catalina) was a dynamically new Oort cloud comet whose apparition presented a favorable geometry for observations near close-Earth approach (≃0.93 au)at heliocentric distances ≲2 au when insolation and sublimation of volatiles drive maximum activity. Here we present mid-infrared 6.0≲λ(μm)≲40 spectrophotometric observations at two temporal epochs from NASA’s Stratospheric Observatory for Infrared Astronomy and the NASA Infrared Telescope Facility that yield an inventory of the refractory materials and their physical characteristics through thermal modeling analysis. The grain composition is dominated by dark dust grains (modeled as amorphous carbon) with a silicate-to-carbon ratio ≲0.9, little crystalline stoichiometry (no distinct 11.2 μm feature attributed to Mg-rich crystalline olivine), and the submicron grain-size distribution peaking at ≃0.6 μm. The 10 μm silicate feature was weak, ≈12.8%0.1% above the local continuum, and the bolometric grain albedo was low (≲14%). Comet C/2013 US₁₀ (Catalina) is a carbon-rich object. This material, which is well represented by the optical constants of amorphous carbon, is similar to the material that darkens and reddens the surface of comet 67P/Churyumov–Gerasimenko. We argue this material is endemic to the nuclei of comets, synthesizing results from the study of Stardust samples, interplanetary dust particle investigations, and micrometeoritic analyses. The atomic carbon-to-silicate ratio of comet C/2013 US₁₀ (Catalina) and other comets joins a growing body of evidence suggesting the existence of a C/Si gradient in the primitive solar system, providing new insight into planetesimal formation and the distribution of isotopic and compositional gradients extant today.

C / 2013 US ₁₀彗星（Catalina）是一种动态新型的奥尔特云彗星，其幻影为近日接近（≃0.93au）在日心距≲2au附近观测时提供了有利的几何形状，这是因为挥发物的日晒和升华驱动了最大活动。在这里，我们本中红外6.0≲ λ（μ M）≲40在两个时间时期从NASA的红外天文和NASA红外望远镜平流层天文台光度法的意见，即通过热建模分析得到的耐火材料和其物理特性的清单。晶粒组成主要是深色尘埃颗粒（建模为无定形碳），硅碳比为0.9，晶体化学计量极少（无明显11.2）。μ归因于富Mg结晶橄榄石m个特征），在≃0.6亚微米粒度分布峰值μ米。10 μ M硅酸盐特征是弱，≈12.8％0.1％的局部连续的上方，并且辐射热谷物反照率是低的（≲14％）。C / 2013 US ₁₀彗星（卡塔利娜）是富含碳的物体。这种材料可以很好地用无定形碳的光学常数表示，类似于使67P / Churyumov-Gerasimenko彗星表面变暗和变红的材料。我们认为这种物质是彗星核的特有物质，它综合了星尘样品研究，行星际尘埃颗粒调查和微气象分析的结果。C / 2013 US ₁₀彗星的原子碳硅酸盐比 卡塔利娜（Catalina）和其他彗星加入的证据越来越多，表明原始太阳系中存在C / Si梯度，这为当今行星的形成以及同位素和组成梯度的分布提供了新的见识。