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Accretion is observed in a wide range of objects with partially overlapping properties. In this paper, we focus on accretion in young stars. Material impacting the stellar surface is shock-heated to temperatures of a few 106 K (MK), which is ideally suited for observations in the X-ray regime. Indeed, young, accreting stars show a surplus of cool plasma, thought to be somehow related to accretion, the so-called soft excess. High-resolution grating spectroscopy with instruments like the Reflection Grating Spectrometer (RGS) on board XMM-Newton allows us to infer the properties of this cool plasma.We present results from our recent 250-ks XMM-Newton/Chandra program targeting the prototypical T Tau system and compare them with other accreting systems, focusing on potentially different accretion modes. We find a strong cool excess in T Tau but line ratios indicative of low densities. Thus, the cool excess in T Tau, and likely in other accreting stars, is not caused directly by postshock emission from accretion spots, which are expected in magnetic stars like T Tau. Rather, the coolest plasma might be linked to other processes in accreting stars, such as an interaction of the corona with postshock plasma. [ABSTRACT FROM AUTHOR]

This contribution summarizes the splinter session 'Non-thermal processes in coronae and beyond' held at the Cool Stars 17 workshop in Barcelona in 2012. It covers new developments in high energy non-thermal effects in the Earth's exosphere, solar and stellar flares, the diffuse emission in star forming regions and reviews the state and the challenges of the underlying atomic databases. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]