Color laws

CCM89(;Rv=3.1)

Clayton, Cardelli and Mathis (1989) dust law.

Returns A(λ)/A(V) at the given wavelength relative to the extinction at 5494.5 Å. The default support is [1000, 33333]. Outside of that range this will return 0. Rv is the selective extinction and is valid over [2, 6]. A typical value for the Milky Way is 3.1.

References

Clayton,Cardelli and Mathis (1989)

OD94(;Rv=3.1)

O'Donnell (1994) dust law.

This is identical to the Clayton, Cardelli and Mathis (1989) dust law, except for different coefficients used in the optical (3030.3 Å to 9090.9 Å).

References

O'Donnell (1994)

See Also

CCM89

CAL00(;Rv=4.05)

Calzetti et al. (2000) Dust Law.

Returns A(λ)/A(V) at the given wavelength. λ is the wavelength in Å and has support over [1200, 22000]. Outside of that range this will return 0.

Calzetti et al. (2000) developed a recipe for dereddening the spectra of galaxies where massive stars dominate the radiation output. They found the best fit value for such galaxies was 4.05±0.80.

References

Calzetti et al. (2000)

VCG04(;Rv=3.1)

Valencic, Clayton, & Gordon (2004) dust law.

This model applies to the UV spectral region all the way to 912 Å. This model was not derived for the optical or NIR.

References

Valencic, Clayton, & Gordon (2004)

GCC09(;Rv=3.1)

Gordon, Cartledge, & Clayton (2009) dust law.

This model applies to the UV spectral region all the way to 909.09 Å. This model was not derived for the optical or NIR.

References

Gordon, Cartledge, & Clayton (2009)

F99(;Rv=3.1)

Fitzpatrick (1999) dust law.

Returns A(λ)/A(V) at the given wavelength relative to the extinction. This model applies to the UV and optical to NIR spectral range. The default support is [1000, 33333] Å. Outside of that range this will return 0. Rv is the selective extinction and is valid over [2, 6]. A typical value for the Milky Way is 3.1.

References

Fitzpatrick (1999)

F04(;Rv=3.1)

Fitzpatrick (2004) dust law.

Returns A(λ)/A(V) at the given wavelength relative to the extinction. This model applies to the UV and optical to NIR spectral range. The default support is [1000, 33333] Å. Outside of that range this will return 0. Rv is the selective extinction and is valid over [2, 6]. A typical value for the Milky Way is 3.1.

Equivalent to the F99 model with an updated NIR Rv dependence

See also Fitzpatrick & Massa (2007, ApJ, 663, 320)

References

Fitzpatrick (2004)

F19(;Rv=3.1)

Fitzpatrick (2019) dust law.

Returns A(λ)/A(V) at the given wavelength relative to the extinction. This model applies to the UV and optical to NIR spectral range. The default support is [1149, 33333] Å. Outside of that range this will return 0. Rv is the selective extinction and is valid over [2, 6]. A typical value for the Milky Way is 3.1.

Fitzpatrick, Massa, Gordon et al. (2019, ApJ, 886, 108) model. Based on a sample of stars observed spectroscopically in the optical with HST/STIS.

References

Fitzpatrick (2019)

M14(;Rv=3.1)

Maiz Apellaniz et al (2014) Milky Way & LMC R(V) dependent model.

Returns A(λ)/A(V) at the given wavelength relative to the extinction. The published UV extinction curve is identical to Clayton, Cardelli, and Mathis (1989, CCM). Forcing the optical section to match smoothly with CCM introduces a non-physical feature at high values of R5495 around 3.9 inverse microns; see section 5 in Maiz Apellaniz et al. (2014) for more discussion. For that reason, we provide the M14 model only through 3.3 inverse microns, the limit of the optical in CCM. Outside of that range this will return 0. Rv is the selective extinction and is valid over [2, 6]. A typical value for the Milky Way is 3.1. R5495 = A(5485)/E(4405-5495) Spectral equivalent to photometric R(V).

References

Maiz Apellaniz et al. (2014)

FM90(;c1=0.10, c2=0.70, c3=3.23, c4=0.41, x0=4.60, gamma=0.9)
FM90(coeffs, x0=4.60, gamma=0.9)

Fitzpatrick & Massa (1990) generative model for ultraviolet dust extinction. The default values are the published values for the Milky Way average.

Parameters

• c1 - y-intercept of linear term
• c2 - slope of liner term
• c3 - amplitude of 2175 Å bump
• c4 - amplitude of FUV rise
• x0 - centroid of 2175 Å bump
• gamma - width of 2175 Å bump

If λ is a Unitful.Quantity it will be automatically converted to Å and the returned value will be UnitfulAstro.mag.

Examples

julia> model = FM90(c1=0.2, c2=0.7, c3=3.23, c4=0.41, x0=4.6, gamma=0.99);

julia> model(1500)
5.2521258452800135

julia> FM90()(1500)
5.152125845280013

julia> FM90(c1=0.2, c2=0.7, c3=3.23, c4=0.41, x0=4.6, gamma=0.99).([1000, 1200, 1800])
3-element Vector{Float64}:
 12.562237969522851
  7.769215017329513
  4.890128210972148

Extended Help

The model has form $c_1 + c_2x + c_3D(x; γ, x_0) + c_4 F(x)$ where $x$ is the wavenumber in inverse microns, $D(x)$ is a Drude profile (modified Lorentzian) used to model the 2175 Å bump with the scale-free parameters $x_0$ (central wavenumber) and $γ$ (damping coefficient), and $F(x)$, a piecewise function for the far-UV. Note that the coefficients will change the overall normalization, possibly changing the expected behavior of reddening via the parameter $A_V$.

References

Fitzpatrick & Massa (1990)

G03_SMCBar(;Rv=2.74) <Internal function>

Gordon et al. (2003) SMCBar Average Extinction Curve.

The observed A(lambda)/A(V) values at 2.198 and 1.25 microns were changed to provide smooth interpolation as noted in Gordon et al. (2016, ApJ, 826, 104)

Reference

Gordon et al. (2003)

G03_LMCAve(;Rv=3.41) <Internal function>

Gordon et al. (2003) LMCAve Average Extinction Curve.

Reference

Gordon et al. (2003)

G16(;Rv=3.1, f_A=1.0)

Gordon et al. (2016) Milky Way, LMC, & SMC R(V) and f_A dependent model

Returns A(λ)/A(V) at the given wavelength relative to the extinction. This is mixture model between the F99 R(V) dependent model (component A) and the G03_SMCBar model (component B). The default support is [1000, 33333] Å. Outside of that range this will return 0. Rv is the selective extinction and is valid over [2, 6]. A typical value for the Milky Way is 3.1.

References

Gordon et al. (2016)

redden(::ExtinctionLaw, wave, flux; Av=1)
redden(::Type{ExtinctionLaw}, wave, flux; Av=1, law_kwargs...)

Redden the given flux using the given extinction law at the given wavelength.

If wave is <:Real then it is expected to be in angstrom and if it is <:Unitful.Quantity it will be automatically converted. Av is the total extinction value. The extinction law can be a constructed struct or a Type. If it is a Type, law_kwargs will be passed to the constructor.

Examples

julia> wave = 3000; flux = 1000;

julia> redden(CCM89, wave, flux; Rv=3.1)
187.38607779757183

julia> redden(CCM89(Rv=3.1), wave, flux; Av=2)
35.11354215235764

See Also

deredden

deredden(::ExtinctionLaw, wave, flux; Av=1)
deredden(::Type{ExtinctionLaw}, wave, flux; Av=1, law_kwargs...)

Deredden the given flux using the given extinction law at the given wavelength.

If wave is <:Real then it is expected to be in angstrom and if it is <:Unitful.Quantity it will be automatically converted. Av is the total extinction value. The extinction law can be a constructed struct or a Type. If it is a Type, law_kwargs will be passed to the constructor.

Examples

julia> wave = 3000; flux = 187.386;

julia> deredden(CCM89, wave, flux; Rv=3.1)
999.9995848273642

julia> deredden(CCM89(Rv=3.1), wave, flux; Av=2)
5336.573541539394

See Also

redden

abstract type DustExtinction.ExtinctionLaw

The abstract supertype for dust extinction laws. See the extended help (??DustExtinction.ExtinctionLaw from the REPL) for more information about the interface.

Extended Help

Interface

Here's how to make a new extinction law, called MyLaw

• Create your struct. We strongly recommend using keyword arguments if your model is parameterized, which allows convenient usage with redden and deredden.

  struct MyLaw <: DustExtinction.ExtinctionLaw end

• (Optional) Define the limits. This will default to (0, Inf). Currently, this is used within the DustExtinction.checkbounds function and in the future will be used for plotting recipes.

  DustExtinction.bounds(::Type{<:MyLaw}) = (min, max)

• Define the law. You only need to provide one function which takes wavelength as angstrom. If your law is naturally written for inverse-micron, there is a helper function aa_to_invum.

  (::MyLaw)(wavelength::Real)

• (Optional) enable Unitful.jl support by adding this function. If you are building a new law within DustExtinction.jl you can add your law to the code-gen list inside DustExtinction.jl/src/DustExtinction.jl.

  (l::MyLaw)(wavelength::Unitful.Quantity) = l(ustrip(u"angstrom", wavelength)) * u"mag"

DustExtinction.bounds(::ExtinctionLaw)::Tuple
DustExtinction.bounds(::Type{<:ExtinctionLaw})::Tuple

Get the natural wavelengths bounds for the extinction law, in angstrom

DustExtinction.checkbounds(::ExtinctionLaw, wavelength)::Bool
DustExtinction.checkbounds(::Type{<:ExtinctionLaw, wavelength}::Bool

Helper function that uses DustExtinction.bounds to return whether the given wavelength is in the support for the law.