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Dust and Diffuse Interstellar Bands in the z(sub a) = 0.524 Absorption System toward AO 0235+164.

DE2004829700

Publication Date	2002
Personal Author	Junkkarinen, V. T.; Cohen, R. D.; Beaver, E. A.; Burbridge, E. M.; Lyons, R. W.
Page Count	44
Abstract	The authors present new HST STIS NUV-MAMA and STIS CCD observations of the BL Lac object AO 0235+164 and the intervening damped Ly (alpha) (DLA) line at z(sub (alpha)) = 0.524. The line profile gives N(HI) = 5 (+-) 1 x 10(sup 21) cm(sup -2) and, combined with the H I 21 cm absorption data leads to a spin temperature of Ts = 220 K (+-) 60 K. Those spectra also show a strong, broad feature at the expected position of the 2175 (angstrom) graphitic dust feature at z(sup (alpha)) = 0.524. Assuming a Galactic type dust extinction curve at z(sub (alpha)) = 0.524 gives a dust-to-gas ratio of 0.19 Galactic, but the fit, assuming the underlying, un-reddened spectrum is a single power-law, is poor in the far-UV. A dust-to-gas ratio of 0.19 Galactic is similar to the LMC, but the AO 0235+164 spectrum does not fit the LMC extinction curve, or the SMC extinction curve (which has practically no 2175 (angstrom) feature). A possible interpretation includes dust similar to Galactic, but with less of the small particles that produce the far-UV extinction. The metallicity of the z(sub (alpha)) = 0.524 absorber, estimated from the observed N(HI) and excess X-ray absorption (beyond Galactic) derived from contemporaneous and archival ASCA and ROSAT.
Keywords	Interstellar grains Cosmic dust Spin Absorption spectra X-ray spectra Astrophysics
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	California Univ., San Diego, La Jolla. Center for Astrophysics and Space Sciences.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200510

Dust and Diffuse Interstellar Bands in the z(sub a) = 0.524 Absorption System toward AO 0235+164.

Dust and Diffuse Interstellar Bands in the z(sub a) = 0.524 Absorption System toward AO 0235+164.
DE2004829700

Publication Date	2002
Personal Author	Junkkarinen, V. T.; Cohen, R. D.; Beaver, E. A.; Burbridge, E. M.; Lyons, R. W.
Page Count	44
Abstract	The authors present new HST STIS NUV-MAMA and STIS CCD observations of the BL Lac object AO 0235+164 and the intervening damped Ly (alpha) (DLA) line at z(sub (alpha)) = 0.524. The line profile gives N(HI) = 5 (+-) 1 x 10(sup 21) cm(sup -2) and, combined with the H I 21 cm absorption data leads to a spin temperature of Ts = 220 K (+-) 60 K. Those spectra also show a strong, broad feature at the expected position of the 2175 (angstrom) graphitic dust feature at z(sup (alpha)) = 0.524. Assuming a Galactic type dust extinction curve at z(sub (alpha)) = 0.524 gives a dust-to-gas ratio of 0.19 Galactic, but the fit, assuming the underlying, un-reddened spectrum is a single power-law, is poor in the far-UV. A dust-to-gas ratio of 0.19 Galactic is similar to the LMC, but the AO 0235+164 spectrum does not fit the LMC extinction curve, or the SMC extinction curve (which has practically no 2175 (angstrom) feature). A possible interpretation includes dust similar to Galactic, but with less of the small particles that produce the far-UV extinction. The metallicity of the z(sub (alpha)) = 0.524 absorber, estimated from the observed N(HI) and excess X-ray absorption (beyond Galactic) derived from contemporaneous and archival ASCA and ROSAT.
Keywords	Interstellar grains Cosmic dust Spin Absorption spectra X-ray spectra Astrophysics
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	California Univ., San Diego, La Jolla. Center for Astrophysics and Space Sciences.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200510