J/A+A/275/549 J/A+A/275/549 Environment dependence of interstellar P Jenniskens J M Greenberg Astron. Astrophys. 275 549 1993 1993A&A...275..549J dust, extinction HII regions reflection nebulae ultraviolet: ISM 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. (1988, A&A S 73, 195) in the parameter scheme of Fitzpatrick E.L. and Massa D. (1988, ApJ 328, 734). 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) = x^2/((x^2-x0^2)^2 + y^2x^2) 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/y^2 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. (1988).

starname Star Name --- k(U) Extinction in U band --- c1 Coefficient (see text) --- c2 Coefficient (see text) um c3 Coefficient (see text) --- c4 Coefficient (see text) --- y Width of the bump um-1 x0 Position of the bump um-1 CHISQ Indication of the deviation between fitted curve and actual data --- Q Quality indication of the data: Q=1 gives a bad fit to the U band extinction, f.e. due to saturation at long wavelength, and spectra marked Q=2 show signs of underexposure in the bump. --- IPSC IRAS point source classification: IPSC=1 is point source with 12 micron flux smaller than 25, IPSC=2 is point source with 25 micron flux smaller than 12. --- TYPE Environment characterisation from IRAS Skyflux maps 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 in creased 60/100 REF: reflection nebulae, small compact regions of highly increased 60/100 associated with B type stars. --- Patricia Bauer CDS 1993Sep10 J_A+A_275_549.xml