J/A+A/275/549 Interstellar extinction curves (Jenniskens+ 1993)
Environment dependence of interstellar extinction curves
Jenniskens P., Greenberg J.M.
<Astron. Astrophys. 275, 549 (1993)>
=1993A&A...275..549J 1993A&A...275..549J
ADC_Keywords: Extinction ; Photometry, ultraviolet
Keywords: ISM: dust, extinction - ISM: HII regions -
ISM: reflection nebulae - Ultraviolet: interstellar
Abstract:
The data are a decomposition of the extinction curves published by
Aiello S., Barsella B., Chlewicki G., Greenberg J.M., Patriarchi P.,
and Perinotto M. (1988A&AS...73..195A 1988A&AS...73..195A) in the parameter scheme of
Fitzpatrick E.L. and Massa D. (1988ApJ...328..734F 1988ApJ...328..734F). Each extinction
curve k(x) = (A(lambda)-A(V))/(A(B)-A(V)) is given by:
k(x) = c1 + c2*x + c3* D(x,x0,y) + c4*F(x)
Where x = 1/wavelength (in inverse micron), D is a Drude profile:
D(x,x0,y) = x2/((x2-x02)2 + y2x2)
and F is a polynomial of order 3:
F(x) = 0.05392(x-5.9)2 + 0.0564(x-5.9)3 for 5.9<x<8.0
F(x) = 0 for x<5.9
In this scheme the parameters have the following meaning:
c1: related directly to c2 because of normalisation k(x)
c2: slope of the linear rise ( mag/E(B-V) )
y: width of the bump (inverse micron)
c3: c3/y2 is bump height, pi*c3/(2.*y) is bump area
x0: position of the bump (inverse micron)
c4: amount of FUV non-linear rise contribution:
at 8 mu-1: 2.9c4 (mag/E(B-V))
| * ^
| * 2.9c4
| ^ * *
k(x)| c3/y^2 * * * .. v
| *< y >* *..
| v * .. * *
| *.. c2
1 | *
0 | *
|^ *
|Rv *
|v|_
V B x0 5.9 8.0
x=1/wavelength (1/micron)
Values of Rv, the ratio of total to selective extinction, can be found in
Aiello et al. (1988A&AS...73..195A 1988A&AS...73..195A).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table 68 115 Extinction coefficients
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Byte-per-byte Description of file: table
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Bytes Format Units Label Explanations
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1- 11 A11 --- starname Designation of star.
13- 16 F4.2 --- k(U) ? Extinction in U band
19- 23 F5.2 --- c1 Coefficient (see text)
24- 28 F5.2 um c2 Coefficient (see text)
29- 33 F5.2 --- c3 Coefficient (see text)
34- 38 F5.2 --- c4 Coefficient (see text)
40- 43 F4.2 um-1 y Width of the bump
45- 49 F5.3 um-1 x0 Position of the bump
52- 56 F5.3 --- chisq Indication of the deviation between fitted
curve and actual data
59 I1 --- Q Quality indication of the data (1)
61 I1 --- IPSC [0/2] IRAS point source classification (2)
66- 68 A3 --- TYPE Environment characterisation from IRAS Skyflux
maps (3)
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Note (1): The quality are:
Q=1 gives a bad fit to the U band extinction, due to saturation at long
wavelength, and spectra marked
Q=2 show signs of underexposure in the bump.
Note (2): IPSC classification as (for IPSC>0):
IPSC=1 is point source with 12 micron flux smaller than 25,
IPSC=2 is point source with 25 micron flux smaller than 12.
Note (3): the characterisation takes the following values:
CS: circumstellar
DIF: diffuse medium line of sight (no aparent heating)
BUB: bubble, extended region of increased 60/100 around OB association
HII: HII region, compact regions of highly increased 60/100
REF: reflection nebulae, small compact regions of highly increased 60/100
associated with B type stars.
(End) Patricia Bauer [CDS] 10-Sep-1993