I am an Astronomer at Space Telescope Science Institute (STScI) which I joined in August 2007 and a Guest Professor at the Department of Physics and Astronomy at the Univerity of Ghent since 2011. My research focus on investigating the properties of interstellar dust grains through observations and modeling. My functional work at STScI centers on supporting absolute flux calibration for all STScI missions, data reduction for all James Webb Space Telescope (JWST) instruments, and the JWST Mid-Infrared Instrument.
From 1999-2007 I worked at the Univ. of Arizona as part of the MIPS Instrument Team participating in the full joys of helping build, operate, and use a space instrument. Prior to that I spent 2 years as a postdoc working with Geoff Clayton at Louisiana State University. I received my PhD in 1997 from the Univ. of Toledo where I got my start in interstellar dust research working for Adolf Witt.
One of the primary observational constraints on dust grain properties is extinction. Extinction is the combined impact of dust grains absorbing photons or scattering out them of the line-of-sight. My work in this area focuses on measuring ultraviolet through infrared dust extinction curves towards stars in the Milky Way, the Magellanic Clouds, and other Local Group galaxies. These observations stongly contrain dust grain sizes and compositions.
A strong observational constraints on dust grain properties is emission. Dust emission can take the form of equilibrium and non-equilibrium thermal emission or non-thermal emissions such as Luminescence. My work in this area focuses on measuring the infrared thermal emissions and optical/NIR non-thermal emissions in the Milky Way and nearby galaxies. Modeling these observations constrains the composition and size of dust grains.
I am privileged to be part of the ISM*@ST research group that focuses on interstellar, circumstellar, and circumgalactic media, mainly in nearby galaxies. But our interests are diverse and we often use stars and stellar populations in our analyses; This group includes a mix of students, postdocs, and staff. I have ideas for projects at all levels and am always interested in hearing from potential collaborators (including students!) interested in working on dust in the Milky Way and nearby galaxies (and even galaxies a bit furthur away than that).
I have been part of a number of large projects both as a simple member, leading major portions, or leading the entire project.
Dust parameter maps calculated from fitting the Spitzer and Herschel Space Telescope observations of the LMC and SMC are provided.
The full extended disk of M31 was imaged with the Spitzer MIPS instrument. Mosaics of all the MIPS observations are provided.
The Pioneer 10/11 spacecraft included an instrument called the Imaging Photopolarimeter (IPP). This instrument produced blue and red maps of the full sky as the Pioneer spacecraft cruised through and beyond the zodiacal dust cloud. The data taken outside the zodiacal dust cloud was used as part of my PhD thesis to determine the efficiency of the dust photoluminescence feature called Extended Red Emission (ERE).
An astropy affiliated python package that provides empirical ultraviolet through infrared interstellar dust extinction models based on observations in the Milky Way and other Local Group galaxies.
The Bayesian Extinction and Stellar Tool (BEAST) fits the ultraviolet to near-infrared photometric SEDs of stars to extract stellar and dust extinction parameters. The stellar parameters are age (t), mass (M), metallicity (M), and distance (d). The dust extinction parameters are dust column (Av), average grain size (Rv), and mixing between type A and B extinction curves (fA).
My main avenue for publishing research is through refereed papers in journals (1st author only). In addition, I have a number of unrefereed publications consisting of conference proceedings, meeting abstracts, and a few white papers.
Another method of publications is press releases. I have been involved in a few highlighting Spitzer and Hubble Space Telescope observations.