标题： SVS13的中红外光谱：原行星盘中的硅酸盐、石英和SiC 显示英文标题

标题： Mid-infrared spectroscopy of SVS13: Silicates, quartz and SiC in a protoplanetary disc

摘要： 我们展示了针对低质量、嵌入式前主序双星系统SVS13的$N$波段（8$-$13 $\mu$m）光谱观测结果。吸收特征被清晰检测到，这些特征归因于无定形硅酸盐、结晶橄榄石、结晶顽火辉石和退火SiO$_{2}$。 最引人注目的是，SVS13周围包层或盘中的尘埃主要成分似乎是SiC，这在总强度和偏振光谱建模中是必需的。 硅碳化物是一种仅在C富集演化恒星大气光谱中被先前检测到的物种，在那里它是尘埃凝结体。 它在星际介质中尚未明确识别，在分子云中从未被发现，更不用说靠近形成中的恒星了。 然而，已经发现在陨石中的前太阳SiC颗粒，可能暗示了SVS13与我们自己的太阳系演化之间有趣的相似性。 该光谱的独特性表明，我们要么是在捕捉SVS13短暂的演化阶段，要么是SVS13本身有某些特殊之处，使其在年轻恒星中显得稀有。 我们推测了相应尘埃物种的物理起源以及为什么它们都同时出现在SVS13方向。 提出了两种情景：盘不稳定性引起的碎裂，随后局部加热和轨道演化首先退火最初无定形的硅酸盐，然后将其晶体产物分散在整个恒星周围的盘中；以及在恒星盘和双星盘界面处新发现的冲击加热机制提供晶体化过程。 其中一个或两个机制作用于碳丰富颗粒材料上也可以合理地产生SiC信号。 显示英文摘要

摘要： We present $N$-band (8$-$13 $\mu$m) spectroscopic observations of the low-mass, embedded pre-main-sequence close binary system SVS13. Absorption features are clearly detected which are attributable to amorphous silicates, crystalline forsterite, crystalline enstatite and annealed SiO$_{2}$. Most intriguingly, a major component of the dust in the envelope or disc around SVS13 appears to be SiC, required to model adequately both the total intensity and polarisation spectra. Silicon carbide is a species previously detected only in the spectra of C-rich evolved star atmospheres, wherein it is a dust condensate. It has not been unambiguously identified in the interstellar medium, and never before in a molecular cloud, let alone in close proximity to a forming star. Yet pre-Solar grains of SiC have been identified in meteorites, possibly suggesting an interesting parallel between SVS13 and our own Solar-System evolution. The uniqueness of the spectrum suggests that we are either catching SVS13 in a short-lived evolutionary phase and/or that there is something special about SVS13 itself that makes it rare amongst young stars. We speculate on the physical origin of the respective dust species and why they are all simultaneously present toward SVS13. Two scenarios are presented: a disc-instability-induced fragmentation, with subsequent localised heating and orbital evolution firstly annealing initially amorphous silicates and then dispersing their crystalline products throughout a circumstellar disc; and a newly discovered shock-heating mechanism at the interface between the circumstellar and circumbinary discs providing the crystallisation process. One or both of these mechanisms acting on carbon-rich grain material can also feasibly produce the SiC signature.