Time-resolved protoplanetary disk physics in DQ Tau with JWST

Aims. Accretion variability is ubiquitous in young stellar objects. While large outbursts (2.5–6 mag) may strongly affect the disk structure, the effects of moderate bursts (1–2.5 mag) are less understood. Our aim is to characterize the physical response of the disk around the eccentric binary system DQ Tau to its periodic accretion changes. Methods. We organized a multi-wavelength observing campaign centered on four JWST/MIRI spectra. We targeted three consecutive periastrons (high accretion state) and one apastron (quiescence). We used optical and near-infrared spectroscopy and photometry to measure how the accretion luminosity varies. We decomposed the multi-epoch spectral energy distributions into stellar, accretion, and rim components. In the MIRI spectra, we fitted the solid-state features using various opacity curves and the molecular features using slab models. Results. We find the inner disk of DQ Tau to be highly dynamic. The temperature, luminosity, and location of the inner dust rim vary in response to the movement of stars and the L_acc variations (0.10–0.40 L_⊙). This causes variable shadowing of the outer disk, leading to an anti-correlation between the rim temperature and the strength of the 10 µm silicate feature. The dust mineralogy remains constant across all epochs, dominated by large (>2 µm) amorphous olivine and pyroxene grains, with smaller fractions of crystalline forsterite. The excitation of CO (1550–2260 K), HCN (880–980 K), and hot H₂O (740–860 K) molecules, as well as the luminosity of the [NeII] line correlate with the accretion rate, while the warm (~650 K) and cold (~170–200 K) H₂O components are mostly constant. CO emission, originating from a hot region (>1500 K) likely within the dust sublimation radius, is the most sensitive to L_acc changes. In comparison with other T Tauri disks, DQ Tau is highly C-poor and displays moderately inefficient pebble drift. Conclusions. We conclude that even moderate accretion rate changes affect the thermal structure in the planet-forming disk regions on short timescales, providing a crucial benchmark for understanding disk evolution.