91福利

Solar flares impulsively release energy in the Sun鈥檚 atmosphere, with a substantial amount going into accelerating electrons. Hard X-ray (HXR) observations are a crucial tool for understanding the properties of this non-thermal emission and RHESSI is successfully able to study this in large flares down to events many orders of magnitude smaller (microflares). To go beyond RHESSI we require X-ray telescopes with higher sensitivity and dynamic range to probe the faint emission from coronal energy release sites associated with flares and CMEs as well as the weak signatures from even smaller impulsive events (nanoflares), that could contribute to heating the corona. As a step towards a dedicated solar spacecraft an opportunity presents itself with NASA鈥檚 NuSTAR. Launched in 2012, NuSTAR is an astrophysics mission using X-ray focusing optics to directly observe faint sources with highly sensitive imaging spectroscopy. Most of NuSTAR鈥檚 time is spent on targets outside of the solar system but some is spent on the Sun. I will present NuSTAR鈥檚 solar observations, that started in late 2014, and have so far observed even smaller flares and faint coronal sources. I will also talk about future prospects for these types of observations