Proba-3/ASPIICS

ASPIICS Wide BandK-Corona Total Brightness, Radially Filtered
ASPIICS Polarized BrightnessK-Corona Polarized Brightness, Radially Filtered
ASPIICS Green LineFe XIV 5303 Å, Integrated Line Radiance
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Another mission we are particularly excited about featuring on the prediction page this year is the Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun (ASPIICS) coronagraph. ASPIICS is part of ESA’s recently launched Proba-3 mission, which uses highly-precise satellite formation flying to occult the bright solar disk with one spacecraft, while measuring the tenuous outer atmosphere of the Sun with the ASPIICS coronagraph.

By using a separate spacecraft as the occulter, ASPIICS does its best to recreate what the moon does when it blocks the Sun on Earth. This allows ASPIICS to overcome many of the challenges that plague traditional coronagraphs when attempting to measure a high dynamic range from the base of the corona, which is very bright, to the extended or middle corona, which is very faint. This unique design of ASPIICS allows it to measure coronal emission from roughly 1.1-3.6 solar radii (RsR_s) with a field of view of ±3\pm 3 RsR_s.

In the above images we use our model to synthesize several of ASPIICS’s key observables, both for the time of totality on August 12 and for the Earth’s view over the duration of the simulation. The first image on the left is the K-coronal total brightness, tBtB, which we use to emulate the wide band visible filter used by ASPIICS. This filter is most like what will see with their naked eye during totality. The middle image is the polarized brightness, pBpB, which ASPIICS also measures using polarizers to filter out unpolarized light. As described on the PUNCH page, the polarized brightness provides complementary information to the total brightness, and is often used as a precise measure of the integrated coronal mass density along the line of sight. Measuring pBpB is also a convenient way to filter out the contributions of the scattering by dust in the corona and inner heliosphere (the F-Corona), which is largely unpolarized this close to the Sun.

Lastly, on the right, we show the integrated emission of the coronal “green line” at 5303 Å, which is measured by ASPIICS using a special filter to isolate this region of the visible spectrum. As described on the Visible and Infrared Emission Line page, this line captures emission from a highly ionized state of iron that is representative of the hot plasma temperature in the magentically closed solar corona. By precisely comparing emission from the broad-band visible measurements (tBtB and pBpB), to line emission measurements like this one, scientist can tease out the temperature and density structure of the solar corona (e.g., as done in a series of papers by Boe et al. 2021, 2022, & 2023).

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ACKNOWLEDGEMENTS

This research is funded by NASA and NSF. We are grateful to Instituto de Astrofísica de Canarias (IAC) for providing a dedicated allocation at the LaPalma supercomputer and proud to support the North African Telescope Eclipse (NATE) project, led by IAC. We also acknowledge dedicated resources from the ACCESS program and Expanse supercomputer at the San Diego Supercomputer Center (SDSC). We thank NASA's Advanced Supercomputing Division (NAS) for allocations on the Athena supercomputer that enabled many of the visualizations on this page to be produced rapidly in real-time. We also thank the SDO/HMI team of the Solar Physics Group at Stanford University for their support in providing timely access to HMI vector magnetograph data. Lastly, we are particularly excited to work with the Solar Orbiter PHI team, to conduct the farside assimilation experiment in near-real-time.