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arXiv · 2606.11026

MINDS survey of silicates in T Tauri disks: Correlation between dust and gas

J. Varga·Th. Henning·L. B. F. M. Waters·I. Kamp·Á. Kóspál·P. Ábrahám·O. Absil·A. M. Arabhavi·D. Gasman·S. L. Grant·M. Güdel·H. Jang·T. Kaeufer·J. Kanwar·N. T. Kurtovic·P. -O. Lagage·G. Perotti·A. Somigliana·L. M. Stapper·B. Tabone·M. Temmink·E. F. van Dishoeck·M. Vlasblom
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Abstract

Context. Silicates are key constituents of planet-forming disks and major building blocks of rocky planets. Mid-infrared spectral features of micron-sized silicate grains trace grain growth, mineralogy, and disk chemistry. Aims. We characterized the dust mineralogy in T Tauri disks using James Webb Space Telescope (JWST)/Mid-Infrared Instrument (MIRI) observations and investigated the connections between the dust and molecular gas compositions. Methods. We analyzed JWST/MIRI spectra of 26 disks from the MIRI mid-Infrared Disk Survey (MINDS). Using our DustComp spectral decomposition tool, we inferred the mass fractions of individual dust species. The fits included Mg$_2$SiO$_4$ (forsterite), MgSiO$_3$ (enstatite), and SiO$_2$ (silica), together with amorphous silicates of corresponding stoichiometry. Results. Mg-rich (and Fe-poor) silicates reproduce the data well, with residuals typically within $\pm3\%$. Grain size distributions are skewed toward sizes larger than $2μ$m, indicating significant growth. The average dust composition is dominated by Mg$_2$SiO$_4$-stoichiometry grains ($\sim60\%$), followed by MgSiO$_3$ ($\sim30\%$) and SiO$_2$ ($\sim10\%$). Crystalline mass fractions are typically in the $5$-$24\%$ range, with a mean of $14\%$. Annealed silica is robustly detected in nine objects, with cristobalite as the main polymorph. We found a correlation between dust and molecular gas composition: disks with strong annealed silica features show stronger CO$_2$ emission, while forsterite-rich disks display stronger H$_2$O emission. Disks with annealed silica features may also have elevated gas-phase C/O ratios. Conclusions. The observed dust-gas correlation may provide the first indication that the molecular gas composition regulates the availability of dust species in the inner disk.

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J. Varga, Th. Henning, L. B. F. M. Waters, I. Kamp, Á. Kóspál, P. Ábrahám, O. Absil, A. M. Arabhavi, D. Gasman, S. L. Grant, M. Güdel, H. Jang, T. Kaeufer, J. Kanwar, N. T. Kurtovic, P. -O. Lagage, G. Perotti, A. Somigliana, L. M. Stapper, B. Tabone, M. Temmink, E. F. van Dishoeck, M. Vlasblom. 2026-06-18. MINDS survey of silicates in T Tauri disks: Correlation between dust and gas. https://doi.org/10.1051/0004-6361%2F202659855

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