astrolibR (version 0.1)

ccm_unred: Deredden a flux vector using the Cardelli et al. (1989) parameterization

Description

Deredden a flux vector using the Cardelli et al. (1989) parameterization

Usage

ccm_unred(wave,flux,ebv,R_V)

Arguments

wave

wavelength in Angstroms, scalar or N-vector

flux

calibrated flux vector, scalar or N-vector

ebv

color excess E(B-V), scalar

R_V

ratio of total to selected extinction, default=3.1 (optional)

Value

funred

unreddened flux, scalar or N-vector.

Details

The reddening curve is that of Cardelli, Clayton, and Mathis (1989), including the update for the near-UV given by O'Donnell (1994). Parameterization is valid from the IR to the far-UV (3.5 microns to 0.1 microns). Curve is extrapolated between 912 and 1000 A as suggested by Longo et al. (1989). R_V specifies the ratio of total selective extinction R(V) = A(V) / E(B - V). If not specified, then R_V = 3.1 Extreme values of R(V) range from 2.75 to 5.3.

Many sightlines with peculiar ultraviolet interstellar extinction can be represented with a CCM curve, if the proper value of R(V) is supplied.

Users might wish to consider using the alternate procedure FM_UNRED which uses the extinction curve of Fitzpatrick (1999).

The CCM curve shows good agreement with the Savage and Mathis (1979) ultraviolet curve shortward of 1400 A, but is probably preferable between 1200 and 1400 A.

Valencic et al. (2004) revise the ultraviolet CCM curve (3.3 -- 8.0 um-1). But since their revised curve does not connect smoothly with longer and shorter wavelengths, it is not included here.

References

Cardelli, J. A., Clayton, G. C., Mathis, J. S., The relationship between infrared, optional, and ultraviolet extinction, Astrophysical Journal, 345, 245-256, 1989. http://adsabs.harvard.edu/abs/1989ApJ...345..245C

Fitzpatrick, E. D., Correcting the effects of interstellar extinction, Publ. Astron. Soc. Pacific, 111, 63-75, 1999. http://adsabs.harvard.edu/abs/1999PASP..111...63F

Longo, R., Stalio, R., Polidan, R. S., Rossi, L., Intrinsic ultraviolet (912-3200 A) energy distribution of OB stars, Astrophysical Journal 339, 474-487, 1989. http://adsabs.harvard.edu/abs/1989ApJ...339..474L

O'Donnell, J. E., R-nu-dependent optical and near-ultraviolet extinction, Astrophysical Journal, 422, 158-163, 1994. http://adsabs.harvard.edu/abs/1994ApJ...422..158O

Savage, B. D. & Mathis, J. S., Observed properties of interstellar dust, Ann. Rev. Astron. Astrophys. 17, 73-111, 1979. http://www.annualreviews.org/doi/pdf/10.1146/annurev.aa.17.090179.000445

Valencic, L. A., Clayton, G., C., Gordon, K. D., Ultraviolet extinction properties in the Milky Way, Astrophysical Journal., 616, 912-924, 2004. http://adsabs.harvard.edu/abs/2004ApJ...616..912V

See Also

calz_unred

Examples

w <- 1200 + seq(50, 2000, by=50)  # wavelength vector
f <- rep(1, length(w))   # flat initial spectrum
ccm_unred(w, f, ebv=0.1)