Atmosphere libraries and coverage

Use this page when choosing whether a local atmosphere product can support a particular parameter point and spectral request without crossing an unvalidated interpolation boundary.

Representation contract¶

Contract field	Current representation
Mathematical object	A product-scoped atmosphere parameter grid whose vertices provide source spectra and whose selected local topology becomes a prepared spectral evaluator.
Physical convention	Released coordinates and density semantics are product-specific; adapters convert to canonical increasing wavelength in nm and surface flux `F_lambda` in CGS per nm.
Runtime owner	`jaxstro.atmospheres` owns catalogs, product identity, topology selection, adapters, artifact reports, and preparation status.
Shape and unit policy	Host catalogs may be ragged or sparse; prepared cells and simplices are fixed-shape PyTrees, and canonical spectra are one-dimensional.
Transform boundary	Host selection is discrete; only evaluation inside a fixed accepted topology has a local JAX transform contract.
Evidence	Real-artifact holdouts, policy manifests, transform tests, and AD-vs-FD checks distinguish adapter availability from accepted runtime policy.
Downstream interpretation boundary	Atmosphere model adequacy, stellar radius, distance, extinction, photometry, instruments, and likelihood semantics remain outside Jaxstro.

Surface spectra and geometry¶

Atmosphere products represent a released surface flux or source-specific precursor, not an observer flux. Under the separate spherical-isotropic geometry assumption,

F_{\lambda,\mathrm{obs}} = \left(\frac{R}{d}\right)^2 F_{\lambda,\mathrm{surface}}.

(1)

Jaxstro can evaluate the algebraic transform when radius and distance are supplied, but the atmosphere library does not silently choose them. The downstream model owns whether (1) is appropriate.

Capability matrix¶

Product family	Released semantic	Canonical conversion	Runtime policy
PHOENIX/NewEra low-resolution v3	wavelength in nm; `F_lambda` in `W m^-2 nm^-1`	multiply density by `1e3`	positive-log accepted
BOSZ 2025 recomputed resampled products	wavelength in angstrom; `F_lambda` per angstrom	angstrom to nm; multiply density by `10`	linear accepted for measured resampled product
Sonora Diamondback 2024	wavelength in micron; wavelength density in `W m^-2 m^-1`	micron to nm; multiply density by `1e-6`	`POLICY_NOT_VALIDATED`
TLUSTY OSTAR2002	frequency in Hz; Eddington flux `H_nu`	`F_nu = 4 pi H_nu`, then density conversion	linear accepted
TLUSTY BSTAR2006, `vturb=2` and `vturb=10`	frequency in Hz; Eddington flux `H_nu`	same explicit TLUSTY conversion	`POLICY_NOT_VALIDATED`

“Adapter implemented” and “runtime policy accepted” are separate claims. Sonora and BSTAR artifacts can be opened and converted, but the registry returns POLICY_NOT_VALIDATED because measured interpolation metrics trade off under the declared selection rule.

Exact product identity¶

Atmosphere interpolation never crosses model family, resolution product, composition plane, cloud prescription, or C/N variant. Product IDs encode those choices. TLUSTY has 27 composition-scoped products rather than three broad dataset aliases, which prevents duplicate (teff, logg) nodes from distinct abundance planes from entering one topology.

Topology and coverage¶

An adapter chooses a complete rectilinear cell first. A sparse region is usable only when its simplex is explicitly approved; there is no nearest-neighbor or arbitrary triangulation fallback. Every selected vertex must cover the requested spectral plan. Expected gaps return structured statuses instead of clamped or extrapolated science.

Prepared evaluation is differentiable only inside the selected fixed topology. Product changes, cell changes, and boundary crossings are discrete host events.

Dataset-specific rationale¶

Sonora filenames encode gravity as SI acceleration while AtmosphereParams.logg uses cgs. The catalog stores the released value and the explicit conversion log10(g_m_s2 * 100).

TLUSTY spectra are ragged and use subgroup-local frequency axes. Some published axes repeat printed coordinates. At the canonical boundary Jaxstro mean-coalesces samples at identical published coordinates before enforcing a strictly increasing wavelength axis, and records that operation in provenance.

The generated policy manifest is stored in source at docs/validation/atmosphere-interpolation.json. See the validation overview for how policy evidence is organized and bounded. See Source artifacts and adapters for artifact mechanics and Spectral coordinates, densities, and prepared evaluation for the runtime ownership chain.