Sean Lonsdale

Student Author: Sean Lonsdale (Class of 2010)

Faculty Author: Dr. Ben Sugerman

Scattered-light echoes offer one of the most effective means to study the structure and make-up of circumstellar and interstellar dust and gas.  These light echoes not only provide the exact three-dimensional positions of scattering dust, but they can also be used to determine the dust’s composition, size and number density.  However, they are very rare and have only been unambiguously resolved around a handful of sources.  Here, we present new data and analyses of echoes  previously discovered around SN 1998bu.   This supernova was a type-Ia  and has illuminated an hourglass-shaped circumstellar nebula up to 30 lt-yr in size.  However, SN 1998bu has also illuminated a plane of interstellar material 300-700 lt-yr in front of the supernova.  We interpret this plane as a 100 lt-yr thick dust lane in the host- galaxy’s (M96) disk.

This research was conducted during the 2008 and 2009 Goucher summer- research program and also for academic credit during the 2008-9 school year.  This project was supported with funding from Hubble Space Telescope Grant HST-GO-10607, and was presented at the Winter 2009 meeting of the American Astronomical Society in San Diego, CA.   Click here for a PDF copy of the poster presented at that meeting.