FM90¶
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class
dust_extinction.shapes.
FM90
(C1=0.1, C2=0.7, C3=3.23, C4=0.41, xo=4.6, gamma=0.99, **kwargs)[source]¶ Bases:
astropy.modeling.Fittable1DModel
FM90 extinction model calculation
Parameters: - C1: float
y-intercept of linear term
- C2: float
slope of liner term
- C3: float
amplitude of “2175 A” bump
- C4: float
amplitude of FUV rise
- xo: float
centroid of “2175 A” bump
- gamma: float
width of “2175 A” bump
Notes
FM90 extinction model
From Fitzpatrick & Massa (1990)
Only applicable at UV wavelengths
Example showing a FM90 curve with components identified.
import numpy as np import matplotlib.pyplot as plt import astropy.units as u from dust_extinction.shapes import FM90 fig, ax = plt.subplots() # generate the curves and plot them x = np.arange(3.8,8.6,0.1)/u.micron ext_model = FM90() ax.plot(x,ext_model(x),label='total') ext_model = FM90(C3=0.0, C4=0.0) ax.plot(x,ext_model(x),label='linear term') ext_model = FM90(C1=0.0, C2=0.0, C4=0.0) ax.plot(x,ext_model(x),label='bump term') ext_model = FM90(C1=0.0, C2=0.0, C3=0.0) ax.plot(x,ext_model(x),label='FUV rise term') ax.set_xlabel(r'$x$ [$\mu m^{-1}$]') ax.set_ylabel(r'$E(\lambda - V)/E(B - V)$') ax.legend(loc='best') plt.show()
(Source code, png, hires.png, pdf)
Attributes Summary
C1
linear term: y-intercept C2
linear term: slope C3
bump: amplitude C4
FUV rise: amplitude gamma
bump: width inputs
outputs
param_names
x_range
xo
bump: centroid Methods Summary
__call__
(x[, model_set_axis, …])Evaluate this model using the given input(s) and the parameter values that were specified when the model was instantiated. evaluate
(in_x, C1, C2, C3, C4, xo, gamma)FM90 function fit_deriv
(in_x, C1, C2, C3, C4, xo, gamma)Derivatives of the FM90 function with respect to the parameters Attributes Documentation
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C1
¶ linear term: y-intercept
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C2
¶ linear term: slope
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C3
¶ bump: amplitude
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C4
¶ FUV rise: amplitude
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gamma
¶ bump: width
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inputs
= ('x',)¶
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outputs
= ('exvebv',)¶
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param_names
= ('C1', 'C2', 'C3', 'C4', 'xo', 'gamma')¶
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x_range
= [3.125, 10.964912280701753]¶
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xo
¶ bump: centroid
Methods Documentation
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__call__
(x, model_set_axis=None, with_bounding_box=False, fill_value=nan, equivalencies=None)¶ Evaluate this model using the given input(s) and the parameter values that were specified when the model was instantiated.
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static
evaluate
(in_x, C1, C2, C3, C4, xo, gamma)[source]¶ FM90 function
Parameters: - in_x: float
expects either x in units of wavelengths or frequency or assumes wavelengths in wavenumbers [1/micron]
internally wavenumbers are used
Returns: - exvebv: np array (float)
E(x-V)/E(B-V) extinction curve [mag]
Raises: - ValueError
Input x values outside of defined range