ChromaStar

ChromaStar (formerly "GrayStar")

Reliably responsive in Chrome, Opera, and sometimes Edge browsers under Windows

OpenStar pedagogical star and planet modeling in JavaScript. Visualization in HTML5. Hover for tips. Ctrl +/- to zoom

Input:

Show/Hide stellar

Stellar parameters

Effective temperature, T_eff (3400 - 50000) K)	Log₁₀ surface gravity, log(g) (0.0 - 5.5 cm s^-2 = dynes g^-1)	Stellar mass (0.1 - 20.0 M_Sun)	Metal content (log₁₀ 0.001 - 10.0 x solar)
κ_Fudge log₁₀ mass extinction (-2.0 - 2.0 log cm² g^-1)	[He/Fe] (-1 - 1)	[C/O] (-2 - 2)	[α/Fe] (-0.5 - 0.5)

Show/Hide habitable zone

Habitable Planet Zone parameters

Organic solvent
Surf pressure (0.6 - 22000 kPa)	Greenhouse effect, ΔT (-200 - +600 K)	Albedo (0.0 - 0.95)
Water	Methane	Ammonia	Carbon dioxide

Show/Hide spectral line

Line center wavelength, λ₀ (350 - 1000 nm)
Line strength:
A₁₂ Number density (2.0 - 11.0)	Log₁₀ Oscillator strength, log f , (-6.0 - +1.0)	Ionization stage	Stage I ground ionization E, χ_I (eV ) (4.0 - 25.0)	Stage II ground ionization E, χ_II( eV ) (5.0 - 55.0)	Stage III ground ionization E, χ_III( eV ) (5.0 - 55.0)	Stage IV ground ionization E, χ_IV( eV ) (5.0 - 55.0)	Excitation E, χ_l ( eV ) (0 - χ_I)
Stage I ground statistical wght, g₁ (unitless) (1 - 100)	Stage II ground statistical wght, g₂ (unitless) (1 - 100)	Stage III ground statistical wght, g₃ (unitless) (1 - 100)	Stage IV ground statistical wght, g₄ (unitless) (1 - 100)	Lower E-level statistical wght, g_L (unitless) (1 - 100)
Line width:
Microturbulence, ξ _T , (0.0 - 4.0 km s^-1)	Particle mass (1 - 60 amu)	Log₁₀ Broadening enhancement, γ_Extra (0.0 - 1.0)	v_Macro (0 - 8 km s^-1)	v_Rot (0 - 20 km s^-1)	i_Rot (0 - 90 ^o)

Show/Hide samples

Sample standard stars
User parameters	Sun	Vega	Regulus	Arcturus	Procyon	Planet hosts	51 Pegasi	61 Cygni A	Proxima Centauri	Fomalhaut
Sample worlds
User parameters	Earth	Venus	Mars	Titan
Sample Fraunhofer and classification spectral lines
User parameters	Na I D₁	Na I D₂	Mg I b₁	Ca II K	Ca II H	Ca I 4227	Fe I 4045	Fe I 4271	He I 4471	He I 4387

Show/Hide performance/realism

Output:

Narrow band Gaussian filter λ (270 - 2550 nm) σ (0.01 - 10 nm)

Plots: Atmosphere Chem Eq (if Atmos plots ON) Radiation field 2-level atom: spectral line

Detailed print-out (below graphs): None Atmospheric structure Flux spectral energy distribution (SED) Specific intensity distribution High resolution spectral line profile Limb darkening coeffs Chem Eq (See Plot section menu)