Op weg naar het observeren van planeetformatie in actie met JWST-MIRI: Kalibratie van MIRI/MRS in the ruimte en de toepassingen voor de studie van water in protoplanetaire schijven

The James Webb Space Telescope (JWST) Mid-InfraRed Instrument (MIRI) Medium Resolution Spectrometer (MRS) covers the 5 to 28 m infrared wavelength range. In addition to spectral information, spatial information is also retained by the MRS by virtue of its integral field unit image slicing optics. There are a variety of undesirable instrument effects that limit our ability to reach the photon noise limit for bright sources and read noise limit for faint sources. These effects include two major sources of error: 1) detector pixel response nonlinearity, and by extension charge migration, and 2) detector internal photon scattering. The former results in a broadening of the point spread function (PSF) and line spread function (LSF) of up to 20%, and therefore blurs the image in both dimensions. The latter results in both an additional broadening in the PSF, and detector interferometric fringing: a sinusoid-like source of noise on the spectral baseline. Both affect the absolute flux calibration of the MRS, and the MRS high-contrast imaging capabilities for detecting faint companions. The first goal of this thesis is to mitigate these major sources of error using empirical methods based on in-flight observations of point sources. One of the applications that relies on excellent quality of spectra, is chemistry in protoplanetary disks. These disks of dust and gas orbit around young stellar objects (YSOs), and are the birthplace of planets. The wavelength range of MIRI/MRS in particular covers the inner 0.1-10 AU of the disks, which is likely the cradle for terrestrial planets like Earth. One of the most sought-after molecules is water. The second goal of this thesis is to study the water emission in the inner regions of protoplanetary disks, and link this to the outer dust disk structure.