Prof. Niranjan Thatte

Abstract:

We present the manufacturing and first results from testing and characterising the SWIFT image slicer. The SWIFT image slicer design is based on the MPE-3D and SPIFFI image slicers. It uses plane mirrors to slice the input field but through a novel, de-magnifying design, using a mosaic of spherical lenses, it achieves a considerable de-magnification. Classical polishing techniques can be applied to manufacture both plane and spherical surfaces with very high surface accuracy and quality reducing aberrations and scattered light. The SWIFT image slicer was manufactured over a 18 months period and was delivered to Oxford in September 2007. The commissioning of the SWIFT instrument will take place in August/September 2008.

Abstract:

We combine VLT/ISAAC NIR spectroscopy with archival HST/WFPC2 and HST/NICMOS imaging to study the central 20"x20" of M83. Our NIR indices for clusters in the circumnuclear star-burst region are inconsistent with simple instantaneous burst models. However, models of a single burst dispersed over a duration of 6 Myrs fit the data well and provide the clearest evidence yet of an age gradient along the star forming arc, with the youngest clusters nearest the north-east dust lane. The long slit kinematics show no evidence to support previous claims of a second hidden mass concentration, although we do observe changes in molecular gas velocity consistent with the presence of a shock at the edge of the dust lane.