Heliospheric solutions

Qorona was built on coronal solutions, whose domain is rooted at the solar surface. A heliospheric solution is different in scale, not physics: its domain starts far above the surface and reaches out toward 1 AU and beyond. The equations, the tracer, the Q⊥ mathematics, and the Thomson scattering are all unchanged; only the numbers baked into the render defaults differ. Icarus, an inner-heliosphere MHD model built on MPI-AMRVAC, is Qorona's first heliospheric input (the model is described in Verbeke et al. 2022, and its current version, Icarus 3.0, in Baratashvili et al. 2025).

Every command runs flag-free on a heliospheric .vtu:

qorona info       data/icarus_snapshot.vtu
qorona run        data/icarus_snapshot.vtu -o hcs_qperp.png
qorona build      data/icarus_snapshot.vtu -o icarus.qor
qorona wl         data/icarus_snapshot.vtu -o wl.png
qorona fieldlines data/icarus_snapshot.vtu -o lines.png
qorona qmap       icarus.qor -o hcs_map.png

The solution category

Each reader declares the category of solution it ingests, corona or heliosphere. The category rides the solution, is shown by info, and is recorded in every run's provenance. COCONUT and MAS are coronal; Icarus is heliospheric. It is the category, not the model name, that decides where the internal shell comes from and which set of render defaults applies, so any future heliospheric model inherits the same handling for free.

Defaults that follow the scale

The parameters coupled to physical scale default to the category's natural value. For a coronal solution they resolve to the locked coronal constants; for a heliospheric solution they derive from the solution's own radial shell (its native inner and outer boundaries). The numbers below illustrate the heliospheric derivation on a sample whose domain runs from 21.5 to 231.5 solar radii:

Parameter	Coronal default	Heliospheric default	On the 21.5-231.5 sample
Internal shell (--inner-radius / --outer-radius)	1.0 / 12.5	the native radial extent	21.5 / 231.5
Camera field of view (--fov)	12.5	2 x outer radius	463
Line-of-sight step (--step)	0.02	field of view / 1250	~0.37
Render occulter (--r-occult, render/run)	1.0	inner radius	21.5
White-light occulter (--r-occult, wl)	1.02	1.02 x inner radius	~21.9
Q-map shell (--radius, qmap)	3.0	3 x inner radius	64.5
Camera latitude (--latitude)	0 (edge-on)	90 (equatorial plane from solar north)	90
White-light vignette (--vignette)	newkirk	adaptive	adaptive

Radii are in solar radii. Explicit flags always override these, in both categories, and the resolved number, never a placeholder, is what the run stamps on the image and writes to provenance.

The white-light occulter sits just above the inner boundary so the empty region below the data is covered, and the adaptive vignette self-calibrates its radial falloff to the image (the Newkirk background is a low-corona density profile with no meaning out here). If adaptive misfits a particularly steep falloff, --vignette none keeps the raw frame under a log stretch.

The two canonical views

The heliospheric default camera looks down from solar north, so the equatorial plane fills the frame. This is the conventional heliospheric presentation, the same top-down layout used by solar-wind models such as ENLIL and EUHFORIA. The Parker-spiral heliospheric current sheet and the streamer belt appear face-on, winding outward as spiral arms:

qorona run data/icarus_snapshot.vtu -o hcs_qperp.png

The edge-on view is one flag away, --latitude 0, the same projection a coronal render uses. It compresses the current sheet into a thin band seen along the plane and is the closest analog of an in-ecliptic imaging geometry:

qorona render icarus.qor -o hcs_edge.png --latitude 0

Grid support and the AMR limitation

The reader handles a single-level separable spherical grid, whether the radial spacing is uniform or stretched. An adaptively refined (AMR, multi-level) file is rejected at read time with a clear error naming the limitation; reading AMR files is deferred until sample data is available. The .dat native AMRVAC datfile is not read either, because its variables are stored in code units whose normalization lives outside the file.