[PCG27-02] Constraining the bulk composition of disintegrating exoplanets with transmission spectroscopy using future space telescopes
Keywords:Exoplanets, Bulk Composition, Infrared Transmission spectra, Rocky planets
In this study, we investigated the feasibility of such observations with future observations of JWST and SPICA. For various minerals composed of primary elements of rocky planets (i.e., Fe, Si, and Mg) and additional rock-forming elements found in the Earth such as Al, Ca, and O, we calculated the extinction cross sections based on Mie theory. Taking into account the spatial distribution of the dust tail, we produced theoretical transmission spectra. Assuming the low-resolution spectrographs of JWST MIRI (5—12 μm) and SPICA SMI (17—36 μm), we evaluated observational conditions to constrain the mineral composition of dust tails.
Based on these simulations, we found that infrared transmission spectra at wavelengths longer than a few μm show different features depending on minerals. Since many spectral features show up in the wavelength regions of JWST and/or SPICA, the combination of those space observations allows us to diagnose the various components of dust tails. JWST will be able to detect absorption peaks of SiO2, Mg2SiO4, and Al2O3 if a disintegrating planet is located within ~200 pc from the Earth with the transit depth deeper than 0.25% (SiO2) — 2% (Al2O3). SPICA can distinguish between other minerals such as Fe2SiO4, FeO, and CaTiO3, assuming a system at ~100 pc with a transit depth of 1—2%. Current and upcoming dedicated missions for transit searches (e.g., TESS, PLATO) would be able to provide optimal targets for this kind of studies.