skyscapes.disk.exovista_parametric ================================== .. py:module:: skyscapes.disk.exovista_parametric .. autoapi-nested-parse:: ExovistaParametricDisk: Simplified JAX forward model of ExoVista's disk model. Reproduces the per-component disk-density formula from ExoVista's C++ ``Image::disk_imager`` (the kernel underlying ``distribute_diskpoints``) deterministically using the LOS-around-midplane kernel shared with ``GraterDisk``. Multi-component scenes (warm + cold + halo, etc.) are built via ``CompositeDisk``. What's reproduced (Stark 2022 / ``Image.cpp``): - Vertical Gaussian with constant opening angle ``hor`` and per-radius normalization (mass per unit r preserved). - Four-region radial profile: r > r0+dr: ``exp(-0.5) * (r/(r0+dr))^-1.5`` (outer halo) |r-r0|r>0: inward decay from Wyatt 1999, eq 3.36, ``exp(-0.5) / (1 + 4 eta (1 - sqrt(r/(r0-dr))))`` r <= rinner: additional ``(r/rinner)^3`` cubic ramp - Three-component Henyey-Greenstein phase function ``sum_i(w_i * HG(g_i))``, with scalar ``(g_i, w_i)`` parameters. - ``nzodis`` density scaling (zodi units). - 1/r^2 stellar illumination dilution (applied by the LOS kernel via division by the squared distance to the star). What's intentionally simplified vs the full ExoVista pipeline: - No Dohnanyi grain-size integration weighted by ``Qsca(s, lambda)``. Wavelength dependence is parameterized phenomenologically through ``Ag_grid`` instead. - No sublimation cutoff ``T < T_sublimate`` (would need stellar Teff and rstar). - No stellar-surface-radius cutoff ``r > r_star``. - ``eta`` is treated as a single grain-size-averaged value, not a per-size quantity (the Image.cpp ``tempeta = eta * rdust/rblow`` produces a color gradient absent here). The class is intentionally faithful to the ExoVista parameterization (``r0_AU``, ``dror``, ``rinner_AU``, ``hor``, ``nzodis``, ``eta``, three HG ``(g_i, w_i)``) rather than a smaller user-friendly subset. ``CompositeDisk`` is the right way to build full multi-component scenes. References: Stark, C. C. 2022, AJ, 163, 105 Classes ------- .. autoapisummary:: skyscapes.disk.exovista_parametric.ExovistaParametricDisk Functions --------- .. autoapisummary:: skyscapes.disk.exovista_parametric.three_component_hg skyscapes.disk.exovista_parametric.exovista_density Module Contents --------------- .. py:function:: three_component_hg(cos_phi, g0, g1, g2, w0, w1, w2) Three-component Henyey-Greenstein phase function. ``pfunc = w0 HG(g0) + w1 HG(g1) + w2 HG(g2)``. The caller is responsible for choosing weights that sum to 1 (we do not normalize here). .. py:function:: exovista_density(r, z, *, r0_AU, dror, rinner_AU, hor, nzodis, eta) ExoVista per-component disk density (Image.cpp formula). Args: r: Disk-frame cylindrical radius [AU]. Must be strictly positive. z: Disk-frame height [AU]. r0_AU: Ring center [AU]. dror: Fractional ring width, ``dr = dror * r0_AU``. rinner_AU: Inner truncation radius [AU]. Below this, an additional ``(r/rinner)^3`` cubic ramp suppresses the density. hor: Opening angle. The local 1-sigma Gaussian vertical scale at radius ``r`` is ``h = r * hor``. nzodis: Density normalization (zodi units). eta: Poynting-Robertson drag / collision-timescale ratio for the inward-decay component. Returns: Per-LOS-sample density (relative units), same shape as ``r`` and ``z``. The caller multiplies by phase function and divides by squared distance to the star. .. py:class:: ExovistaParametricDisk Bases: :py:obj:`skyscapes.disk.base.AbstractDisk` ExoVista-style disk component (faithful per-component reproduction). Attributes (PyTree leaves, fittable): r0_AU: Ring center radius [AU]. dror: Ring fractional width ``Delta r / r0`` (dimensionless). rinner_AU: Inner truncation radius [AU]; below this the density is suppressed by ``(r/rinner_AU)^3``. Set to a value smaller than ``rmin_AU`` to disable. hor: Opening angle (Gaussian vertical scale / radius). nzodis: Density normalization in zodi units. eta: PR-drag / collision-timescale ratio at ``r0 - dr``. g0, g1, g2: Three-component HG asymmetry parameters. w0, w1, w2: Three-component HG weights. Should sum to 1; not enforced. rmin_AU: LOS-integration inner bound [AU]. rmax_AU: LOS-integration outer bound [AU]. wavelengths_nm: 1-D wavelength grid for ``Ag_grid``. Queries outside this range return NaN. Ag_grid: Phenomenological albedo scaling vs wavelength. Static attributes: nx, ny: Output image shape. pixel_scale_arcsec: Pixel scale [arcsec/pixel]. dist_pc: System distance [pc]. n_slices_los: Number of LOS integration slices. n_scale_heights: LOS half-extent in units of the scale height at ``rmax_AU`` (default 6.0). .. py:attribute:: r0_AU :type: jaxtyping.Array .. py:attribute:: dror :type: jaxtyping.Array .. py:attribute:: rinner_AU :type: jaxtyping.Array .. py:attribute:: hor :type: jaxtyping.Array .. py:attribute:: nzodis :type: jaxtyping.Array .. py:attribute:: eta :type: jaxtyping.Array .. py:attribute:: g0 :type: jaxtyping.Array .. py:attribute:: g1 :type: jaxtyping.Array .. py:attribute:: g2 :type: jaxtyping.Array .. py:attribute:: w0 :type: jaxtyping.Array .. py:attribute:: w1 :type: jaxtyping.Array .. py:attribute:: w2 :type: jaxtyping.Array .. py:attribute:: rmin_AU :type: jaxtyping.Array .. py:attribute:: rmax_AU :type: jaxtyping.Array .. py:attribute:: wavelengths_nm :type: jaxtyping.Array .. py:attribute:: Ag_grid :type: jaxtyping.Array .. py:attribute:: nx :type: int .. py:attribute:: ny :type: int .. py:attribute:: pixel_scale_arcsec :type: float .. py:attribute:: dist_pc :type: float .. py:attribute:: n_slices_los :type: int .. py:attribute:: n_scale_heights :type: float .. py:method:: _zmax_AU() LOS half-extent in disk-frame z, evaluated at the ring center. For ExoVista-style disks the mass is concentrated near ``r0_AU`` (ring + nearby halo + inward profile), and the radial profile decays as ``r^-1.5`` outside. Using ``r0_AU`` rather than the LOS-bound ``rmax_AU`` gives an LOS extent matched to where the density actually lives, so per-slice dz scales with the scale height at the ring rather than with the (much larger) LOS-bound. .. py:method:: surface_brightness(wavelength_nm, time_jd, incl_deg, pa_deg) Render the ExoVista-style disk on a sky-plane grid. .. py:method:: spatial_extent() Return ``(width_arcsec, height_arcsec)``. .. py:method:: __repr__() Compact summary of ring/density/HG parameters + image/Ag grid.