I'm Amy Steele
About Me.
I am an astronomer and educator. I received my Ph.D. from the University of Maryland at College Park, and have degrees from Williams College and Wesleyan University. My research focuses on circumstellar material around stars at different stages of evolution: debris disks around main sequence stars, mass loss from evolved giant stars, and the characterization of exoplanetary material tidally disrupted by white dwarf stars. These systems collectively inform our understanding of planetary system composition and the long-term fate of our Solar System and its contents. I also work on the optical properties of planetary materials, including the construction of optical constants for use in radiative transfer modeling across a broad wavelength range. Alongside my research, I have worked extensively in science outreach, education, and program coordination at observatories and universities across the United States.
My Work
Debris disks around Sun-like stars
Debris disks around main sequence stars are generated through the collisions of planetesimals that are remnants of stellar evolution. Spatially resolved observations are crucial to characterize the structure of the dust disk and break degeneracies inherent in SED modeling. Using submillimeter wavelength observations I show that gas-poor debris disks around solar analogues generally exhibit properties consistent with scaled-up versions of the Solar System's Kuiper Belt.
Paper: Resolved mm-wavelength observations of debris disks
Poster: AAS2016
Polluted white dwarf stars
If a WD is in the process of ripping apart an exoplanetary body, light that interacts with the resulting gas would reveal the chemical composition of the disrupted body through an absorption and/or emission spectrum (WD spectra typically contain only H or He absorption lines that are gravitationally redshifted). Features from elements heavier than H or He (i.e., metals) in WD spectra are thought to originate from planetary system material. The existence of WDs with metals in their photospheres and evidence of circumstellar gas tied to the tidal disruption of a planetesimal, has provided a new method to determine the composition of extrasolar planetary bodies.
Poster: AAS2017
Modeling a polluted white dwarf
If an exo-asteroid or exo-planet were to get too close to a compact object like a white dwarf, the remnant of evolution for ~95% of stars, it could be ripped apart due to tidal forces. If the geometry is just right, we might see the distrupted pieces transit the white dwarf. This is the case for a number of systems, most notable WD 1145+017.
Paper: A Characterization of the Circumstellar Gas around WD 1124-293 using Cloudy
Poster: AAS2019
Using polluted white dwarfs
As cosmic mass spectrometers, white dwarfs--through their spectra--reveal the chemical makeup of the disrupted remnants of their planetary systems. That information can be used to inform the modeling of dust around other stars, even those like the sun. A disk model for these systems should include both gas and dust. Using the spread in mineral types observed around polluted white dwarfs as motivation, we how one can calculate and construct their own optical constant datasets for use in codes like Cloudy.
ArXiv Paper Link (Coming soon!)