Bringing the Drake Equation Down to Earth
I am an astrobiologist and forthcoming author of LIFE IN SEVEN NUMBERS: THE DRAKE EQUATION REVEALED. I am currently faculty at Tacoma Community College. I received my B. S. in Physics & Astrophysics from Florida State University in 2015 and my Ph. D. in Physics from the University of Notre Dame in 2020, and completed one postdoc at the University of Michigan in 2022, and another at the University of Washington in 2023. My academic research focused on constraining the earlier terms of the Drake Equation: the fraction of stars which host planets, the fraction of planets which could support life, and the fraction of planets which do support life. This quarter at TCC I teach ASTR 115 (Stars, Galaxies, and the Cosmos) and PHYS 114 (General Physics I)
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Does 55 Cnc e Host An Atmosphere?
The lava planet 55 Cnc e could host a number of atmospheres, or none at all. Using the MAROON-X spectrograph on Gemini-N, I am working to understand whether this planet more closely resembles Venus, Mercury, or something else entirely.
Photo credit: EurekAlert
Better Exoplanet Spectroscopy with New Techniques
High-resolution ground-based exoplanet spectroscopy’s greatest challenge is the successful extraction of the exoplanet’s spectrum from the star’s spectrum as well as the spectrum of the Earth’s atmosphere. Often imperfect detectors and reduction pipelines leave residual deviations in spectra which persist into the cross-correlation analysis of data against model and cause low detection significances or non-detections. Our new methods, outlined in Rasmussen et al. (2021a), address these deviations and lead to better, more decisive detections of molecular species in exoplanet atmospheres.
Photo credit: NASA
The Cutting Edge of Atmospheric Analysis: Multi-phase Observations of Ultra-hot Jupiters
While Hot- and Ultra-hot Jupiters are uninhabitable to life as we know it, they are fascinating astrophysical laboratories for new and exotic atmospheric physics. In addition, they represent a valuable testing ground for cutting-edge analysis methods such as multi-phase spectroscopy, in which the planet is observed at several points in its orbit in order to constrain its three-dimensional properties. Rasmussen et al. (2021b) is available upon request.
Photo credit: NASA/JPL
SEAMSTRESS:
The Search for Exoplanets Around Metal-Poor Stars with TESS
When did planets first begin to form in the Universe? What were they made of, and what were their host stars like? SEAMSTRESS is a robust survey combining the scales of TESS with that of several large-scale surveys of ancient (metal-poor) stars (SkyMapper, Gaia, LAMOST, GALAH, APOGEE, and Pristine) to learn more about life’s oldest origins.
Photo credit: ESA
Graduate Work
Metal-Poor Stars from SALT
Using the South African Large Telescope, I studied the elemental composition of metal-poor stars. Metal-poor stars are unique objects dating back to the earliest generations of stars. In their photospheres, they contain the chemical signature of the first nucleosynthesis events in the Universe, including first stars and neutron star mergers. Link here.
Uranium Observed in a Metal-Poor r-I Star
Uranium, created by the rapid neutron capture process (r-process) in neutron star mergers (NSM), is the heaviest metal observable in a star, and one of only two observable actinides. Measurements of U function as both an indicator of actinide production in NSMs and a cosmochronological clock. Here we present the sixth-ever detection of U in a metal-poor star, and the first belonging to a star in the “r-I” (only moderately enriched in r-process elements) class.
Chemical Tagging with R-Process-Enhanced Metal-Poor Stars
The assembly of the Milky Way’s halo is an open question in the field of Galactic chemodynamical evolution. By analyzing the chemical properties of metal-poor r-process stars, we can infer the sizes of their natal stellar systems. We construct a mass distribution function and show that small stellar systems, due to low chemical dilution capabilities, are capable of producing a wide range of r-process enhancement levels, while large systems with high dilution capabilities are only capable of producing non-enriched to moderately-enriched (“r-I”) stars.