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

We explore the imprint of the cosmological hydrogen recombination lines on the power spectrum of the cosmic microwave background (CMB). In particular, we focus on the three strongest lines for the Balmer, Paschen and Brackett series of hydrogen. We expect changes in the angular power spectrum due to these lines of about 0.3 μK for the Hα line

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Nuclear rings are characterized by their high star formation rates, and are believed to be the products of gas inflow towards the inner regions of spiral galaxies. We present first results from a statistical survey of these rings, aimed to provide an insight into their triggering mechanisms and star formation properties. We gathered photometric

We present results from near-infrared integral-field spectroscopy of the circumnuclear starburst in M83, using the CIRPASS instrument on Gemini South. The combination of Paβ, CO (6,3), and [Fe II] equivalent width measurements over large contiguous regions allows us to track the spatial propagation of star formation across the ringlet, which is too

We present initial results from infrared and visible observations of two comet-asteroid transition objects. 944 Hidalgo is one of the asteroids most likely to be an extinct or dormant comet. Comet 162P/Siding Spring (henceforth 162P), displayed intermittent cometary activity shortly after discovery in late 2004. This comet is the third inner solar