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Abridged. We observed the 40 Myr old star DS Tuc A with XMM-Newton andrecorded two X-ray bright flares, with the second event occurring about 12 ksafter the first one. Their duration from the rise to the end of the decay wasof about 8-10 ks in soft X-rays (0.3-10 keV). The flares were also recorded inthe band 200-300 nm with the UVM2 filter of the Optical Monitor. The durationof the flares in UV was about 3 ks. The observed delay between the peak in theUV band and in X-rays is a probe of the heating phase followed by theevaporation and increase of density and emission measure of the flaring loop.The coronal plasma temperature at the two flare peaks reached 54-55 MK. Thediagnostics based on temperatures and time scales of the flares applied tothese two events allow us to infer a loop length of 5-7 x 10^10 cm, which isabout the size of the stellar radius. We also infer values of electron densityat the flare peaks of 2.3-6.5 x 10^11 cm^-3 , and a minimum magnetic fieldstrength of order of 300-500 G needed to confine the plasma. The energyreleased during the flares was of order of 5-8 x 10^34 erg in the band 0.3-10keV and 0.9-2.7 x 10^33 erg in the UV band (200-300 nm). We speculate that theflares were associated with Coronal Mass Ejections (CMEs) that hit the planetabout 3.3 hr after the flares and dramatically increasing the rate ofevaporation of the planet. From the RGS spectra we retrieved the emissionmeasure distribution and the abundances of coronal metals during the quiescentand the flaring states. In agreement with what inferred from time resolvedspectroscopy and EPIC spectra, also from the analysis of RGS spectra during theflares we infer a high electron density.

X-ray flares of the young planet host DS Tuc A