Speaker
Description
Young stellar objects (YSOs) exhibit variability over a wide range of timescales and amplitudes, driven by stellar activity, variable extinction and disc accretion. Disentangling these processes remains challenging, yet their variability provides key insights into stellar mass assembly and the evolution of young planetary systems. The broad wavelength coverage and spectroscopic capabilities of the Ariel space mission offer a unique opportunity to extend its scientific return through time-domain observations of variable circumstellar environments.
We investigate Ariel's potential for complementary observations of a representative sample of YSOs and planetary systems exhibiting transient extinction phenomena. As a first step, we perform scheduling simulations to assess the cadence and integration times available for complementary targets. We then use preliminary instrument performance simulations to estimate the achievable signal-to-noise ratio across Ariel's wavelength range for representative sources. Particular attention is given to both quiescent and outbursting YSOs, where structural changes in the inner disc drive pronounced photometric and spectroscopic variability. Ariel's 1–8 $\mu$m coverage is especially sensitive to hot dust near the inner disc rim, while longer wavelengths probe cooler material and trace changes in disc structure.
We also examine complementary science cases involving transient dust-producing events. Extreme debris discs exhibit strong warm-dust emission and significant infrared variability, making multi-epoch Ariel observations well suited to tracking the evolution of dust emission and composition following catastrophic planetesimal collisions. In addition, radiative-transfer modelling indicates that the wavelength dependence of exocomet transit signatures can constrain dust composition and grain-size distributions, providing new insights into the physical processes governing these events. Such signatures are expected to be detectable with Ariel.
Our results provide a first assessment of Ariel's potential for time-domain complementary science beyond its core exoplanet programme, demonstrating how repeated photometric and spectroscopic observations can probe accretion, dust evolution, and transient phenomena in young planetary systems.