The Micro Solar-Flare Apparatus (MiSolFA)

The MiSolFA project aims at developing a compact X-ray detector to be flown in a near-Earth orbit during the next solar maximum period (from year 2022 onward).

MiSolFA will achieve its main science goals by complementing solar flare observations performed by the Spectrometer Telescope for Imaging X-rays (STIX) instrument of the ESA/NASA Solar Orbiter mission *.

By looking at the same event from two different points of view, STIX and MiSolFA will be able to obtain for the first time a 3-dimensional view of the X-ray emitting regions with two cross-calibrated instruments.

This will allow for a quantitative estimation of the energy-dependent X-ray emission ratio as a function of the viewing angle.  In turn, this information can be used to infer about the anisotropy of the distribution of the electrons accelerated during the flare, because they are the particles that loose energy in the form of X-ray photons (by bremsstrahlung emission).

Furthermore, looking at flares whose “footpoints” at the chromosphere are occulted for one of the two instruments, they will be able to precisely compare for the first time the energy spectra of the X-ray photons emitted by the coronal and chromospheric sources.  So far, the dynamic range limitations of X-ray imaging spectrometers have prevented us from obtaining simultaneous observation of both kinds of sources, because the emission in the corona is much fainter than the chromosphere (there are at least a couple of orders of magnitude between them, due to the much higher density at the chromosphere).

MiSolFA is being developed by an international collaboration, with a science programme led by the FHNW heliophysics group in Windisch, Switzerland.  The news section allows to follow the ongoing development.

* For the current launch date (Feb 2020), the cruise phase of Solar Orbiter is about 1.5 y and nominal observations will start in Nov 2021. More details on this presentation.

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