原行星盘“类地”区域内行星的构成要素。

The building blocks of planets within the 'terrestrial' region of protoplanetary disks.

作者信息

van Boekel R, Min M, Leinert Ch, Waters L B F M, Richichi A, Chesneau O, Dominik C, Jaffe W, Dutrey A, Graser U, Henning Th, de Jong J, Köhler R, de Koter A, Lopez B, Malbet F, Morel S, Paresce F, Perrin G, Preibisch Th, Przygodda F, Schöller M, Wittkowski M

机构信息

Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands.

出版信息

Nature. 2004 Nov 25;432(7016):479-82. doi: 10.1038/nature03088.

DOI:10.1038/nature03088

PMID:15565147

Abstract

Our Solar System was formed from a cloud of gas and dust. Most of the dust mass is contained in amorphous silicates, yet crystalline silicates are abundant throughout the Solar System, reflecting the thermal and chemical alteration of solids during planet formation. (Even primitive bodies such as comets contain crystalline silicates.) Little is known about the evolution of the dust that forms Earth-like planets. Here we report spatially resolved detections and compositional analyses of these building blocks in the innermost two astronomical units of three proto-planetary disks. We find the dust in these regions to be highly crystallized, more so than any other dust observed in young stars until now. In addition, the outer region of one star has equal amounts of pyroxene and olivine, whereas the inner regions are dominated by olivine. The spectral shape of the inner-disk spectra shows surprising similarity with Solar System comets. Radial-mixing models naturally explain this resemblance as well as the gradient in chemical composition. Our observations imply that silicates crystallize before any terrestrial planets are formed, consistent with the composition of meteorites in the Solar System.

摘要

我们的太阳系由一团气体和尘埃形成。大部分尘埃质量包含在无定形硅酸盐中，但结晶硅酸盐在整个太阳系中都很丰富，这反映了行星形成过程中固体物质的热和化学变化。（即使是彗星等原始天体也含有结晶硅酸盐。）关于形成类地行星的尘埃的演化，我们所知甚少。在此，我们报告了在三个原行星盘最内侧两个天文单位内这些构成物质的空间分辨探测和成分分析。我们发现这些区域的尘埃高度结晶，比迄今在年轻恒星中观测到的任何其他尘埃都更甚。此外，一颗恒星的外部区域辉石和橄榄石含量相等，而内部区域则以橄榄石为主。内盘光谱的光谱形状与太阳系彗星表现出惊人的相似性。径向混合模型自然地解释了这种相似性以及化学成分的梯度。我们的观测表明，硅酸盐在任何类地行星形成之前就已结晶，这与太阳系陨石的成分一致。