About Starless v1.3.1
What this simulates: isolated bodies with no host-star radiation. Mass and bulk metal fraction Z are independent initial conditions, not a Bern-style accretion simulation. A massive body does not pull in hydrogen automatically; gas accretion requires an external reservoir and formation history.
Mass conservation: Fe–Ni, MgSiO₃, H₂O, NH₃, CH₄, CO₂, H₂ and He are tracked in separate mass reservoirs. Iron, Rock and Ices redistribute only the heavy fraction; Outgassing transfers material from existing compounds, never creates additional molecules. Elements are counted from the compound formulas, but chemical reactions and realistic condensation sequences are not yet solved. The compound proportions are illustrative inputs, not equilibrium abundances.
Published physics: cold solid radii use the exact analytic fit of Seager et al. (2007), equation (23) and Table 4, for the pure Fe, silicate and H₂O endpoints. Their mass-weighted specific-volume interpolation for mixtures is our approximation , not a published layered interior calculation. It is most reliable for cold predominantly solid bodies below roughly 20 Earth masses.
Hydrogen-rich bodies: when covered and Z ≤ 5%, radius and effective temperature are interpolated from the solar-atmosphere Sonora Bobcat published tracks (Marley et al. 2021). These are not a complete solution for user-selected core chemistry. Outside the tabulated mass/age range, a labelled illustrative cooling surrogate applies; no physical continuity at its boundaries is guaranteed. The interior H/He pressure profile is an n=1 polytrope approximation. Purple-toned hydrogen appears where the approximate pressure exceeds 2 Mbar. Metallic hydrogen is a fluid state, not a boundary where gas literally ends; the real molecular-to-metallic transition depends on pressure, temperature and EOS.
Thermal estimates: cold solids retain the prior illustrative formation-heat and radiogenic model; H/He-dominated bodies use Sonora Bobcat tabulated effective temperatures where covered and otherwise a labelled approximate cooling scaling. Temperatures are effective internal radiating temperatures, not habitable surface temperatures. There is no external irradiation, greenhouse calculation, or full stellar evolution/nuclear network. Higher-mass regimes are schematic.
Evolution checkpoint v1.2: Beyond giant planets, mass/radius/temperature transitions are educational approximations, not a coupled stellar structure or collapse calculation. Stellar classification, approximate main-sequence lifetimes and remnant scenarios depend on assumed initial composition, a rough mass cutoff and age. Unsupported high-Z high-mass bodies are explicitly flagged. For a remnant, the initial chemical reservoir is shown separately from estimated ejecta; it is not the remnant chemistry. White dwarf radii follow a cold-degenerate Nauenberg fit; neutron-star 12-km radii are assumed; black-hole event-horizon radii follow the nonspinning Schwarzschild metric for assumed remnant masses. These are not evolutionary predictions. No black-hole accretion disk is simulated.
Atmosphere: a deep H/He envelope is physically different from a trace atmosphere above a solid surface. For envelope-rich bodies, the displayed composition refers to bulk H₂/He and mobile trace condensables, not a predicted observable photospheric spectrum or known pressure at a solid surface.
Habitability: the existing screening indicator is disabled for deep H/He-envelope objects, where a familiar rocky or icy surface cannot be assumed. Green indicators are ingredient screens only; no liquid ocean, nutrients, metabolism or life is proven. The taxonomy tabs remain illustrative. Tooltips appear after 1.5 seconds over labels, expand after 2.5 seconds total, and never block sliders.
Sources and next upgrade: Seager et al. 2007 solid radii, Fortney et al. 2007 irradiated giants (comparison), Militzer–Hubbard 2013 H/He EOS (not yet integrated), Zeng–Sasselov 2013 ternary and degeneracy, and Sonora Bobcat isolated evolution tables (radius and effective temperature integrated for covered solar-atmosphere tracks). Consult the release notes for model limitations and numerical checks.
Scientific confidence badges: Published model means selected observable quantities are directly interpolated from a published track within its coverage —not that every interior layer is solved. Approximate means an explicitly simplified, physically motivated calculation. Outside model means the requested parameters exceed supported model coverage, including hypothetical deep-future extrapolation. Physically inconsistent is reserved for contradictory or invalid inputs and should normally be rejected before calculation; it does not mean merely unusual. Click the badge to view its justification.
Age horizon: The normal slider stops near 13.8 billion years of body age. Continue beyond its end or select the unlock button to explore up to a trillion years, then onward to a quadrillion years. This is hypothetical future evolution, not a claim that an object could already be older than the observable universe. Bobcat cooling tracks are not extrapolated beyond their tabulated limits.
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