XRISM/Xtend Analysis of X-ray Flare and Dimming Events on the Young Solar-type Star AB Doradus

Young solar-type stars frequently produce superflares with energies more than an order of magnitude larger than the largest flares observed on the present-day Sun. In solar flares, magnetic energy release drives coronal dynamics such as chromospheric evaporation and coronal mass ejections (CMEs). However, such flare-driven coronal dynamicsplasma motions on stars than the Sun remain poorly understood, although they are important for assessing the impact of high-energy X-ray radiation and eruptive events CMEs on surrounding planetary environments. Here we performed XRISM 5-day X-ray monitoring campaign observations of AB Doradus, a nearby rapidly rotating K-type young star at about 15 pc and an age of approximately 50 Myr. Its high magnetic activity and frequent flaring make it an ideal proxy for investigating the activity of the young Sun. XRISM carries Resolve, a unprecedented high-resolution X-ray microcalorimeter covering the 1.7-12 keV band, and Xtend, an X-ray imaging spectrometer covering the 0.4-13 keV band. Multiwavelength data were also obtained during almost the same period, including ultraviolet spectroscopy with HST/COS, optical photometry with TESS, ground-based optical spectroscopic observations with LCO/NRES, SAAO/SpUpNIC, ESO telescope/PLATOSpec, and AAT, and radio observations with MeerKAT. From the Xtend data, we detected 27 flares during a total exposure of approximately 350 ks. We also found soft X-ray dimming events, characterized by decreases in the soft X-ray count rates. Such dimmings may be caused by evacuation of X-ray-emitting coronal plasma associated with stellar CMEs, by absorption of stellar radiation due to cool eruptive/slingshot prominences, or just by stellar rotation. In this presentation, we focus on the soft X-ray dimmings observed by Xtend and compare spectra before and during/after the dimming intervals. By examining changes in plasma temperature, emission measure, and absorption column density, we will test which mechanism is responsible for the observed dimmings.