The Interpretation of a 2175A Absorption Feature in the Gravitational Lens Galaxy SBS0909 + 532 at z = 0.83.

Comparison of recent spectra by V. Motta et al. (V. Motta et al.: Astrophys. J. 574, 719–725) of two images of a distant gravitationally lensed quasar ( z = 1.38) leads to an extinction curve of the lens galaxy ( z = 0.83) showing clear evidence of a 2175A absorption feature. We compare these data with measured extinction curves from the Galaxy, LMC and SMC and with predictions from models. As it has been found by other authors in the Local Group galaxies we found that the SBS 0909 + 532 curve is compatible with three component models of classical spherical grains and PAHs. We note that apart from this standard point of view, the fits also admit an interpretation in terms of products of a biological origin involving three grain components. [ABSTRACT FROM AUTHOR]