VCG04¶

class dust_extinction.parameter_averages.VCG04(*args, meta=None, name=None, **kwargs)[source]¶

Bases: BaseExtRvModel

Valencic, Clayton, & Gordon (2004) Milky Way R(V) dependent model

Parameters:

Rv: float: R(V) = A(V)/E(B-V) = total-to-selective extinction

Raises:

InputParameterError: Input Rv values outside of defined range

Notes

From Valencic, Clayton, & Gordon (2004, ApJ, 616, 912) Including erratum: 2014, ApJ, 793, 66

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

Example showing V04 curves for a range of R(V) values.

import numpy as np
import matplotlib.pyplot as plt
import astropy.units as u

from dust_extinction.parameter_averages import VCG04

fig, ax = plt.subplots()

# generate the curves and plot them
x = np.arange(3.3,8.0, 0.1)/u.micron

Rvs = ['2.0','3.0','4.0','5.0','6.0']
for cur_Rv in Rvs:
   ext_model = VCG04(Rv=cur_Rv)
   ax.plot(x,ext_model(x),label='R(V) = ' + str(cur_Rv))

ax.set_xlabel(r'$x$ [$\mu m^{-1}$]')
ax.set_ylabel(r'$A(x)/A(V)$')

# for 2nd x-axis with lambda values
axis_xs = np.array([0.12, 0.15, 0.2, 0.3])
new_ticks = 1 / axis_xs
new_ticks_labels = ["%.2f" % z for z in axis_xs]
tax = ax.twiny()
tax.set_xlim(ax.get_xlim())
tax.set_xticks(new_ticks)
tax.set_xticklabels(new_ticks_labels)
tax.set_xlabel(r"$\lambda$ [$\mu$m]")

ax.legend(loc='best')
plt.show()

(Source code, png, hires.png, pdf)

../_images/dust_extinction-parameter_averages-VCG04-1.png

Attributes Summary

`Rv_range`
`x_range`

Methods Summary

evaluate(in_x, Rv)

VCG04 function

Attributes Documentation

Rv_range = [2.0, 6.0]¶

x_range = [3.3, 8.0]¶

Methods Documentation

static evaluate(in_x, Rv)[source]¶

VCG04 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:

axav: np array (float): A(x)/A(V) extinction curve [mag]

Raises:

ValueError: Input x values outside of defined range

Navigation

VCG04¶