Date of Award
Doctor of Philosophy (PhD)
To further our understanding of how forming stars and planetary atmospheres can survive large inputs of radiative and kinetic energy, I have undertaken observational studies of the Orion BN/KL outflow and a sample of nearby M dwarfs with exoplanets. The Orion BN/KL explosive outflow is a spectacular, wide-angle ensemble of hundreds of protostellar-like jets. With near-IR integrated intensity maps of 13 ro-vibrational H2 lines, I determined the excitation conditions across the arcminute-scale, wide-angle BN/KL outflow at 1" resolution. The warm H2 populations (~2000-2500 K) are consistent with collisional excitation by shocks, but small areas are likely excited radiatively. As a potentially common phenomenon in massive star forming regions and a test bed for shock models due to its brightness, the BN/KL is important to characterize in detail.
Exoplanets orbiting stars less massive than the Sun are prime targets for current and near-future atmospheric characterization efforts, because they are nearby and offer larger signals. However, it is an open question whether a habitable-zone rocky planet could maintain an atmosphere through all of the expected mass-loss processes driven by the parent star, especially from high-energy photons and particles. I have characterized the far-UV spectra of 11 K and M dwarfs, determined a correlation between the far- and near-UV spectra and more easily-obtained optical spectra, and developed a method for estimating stellar particle output associated with flares. These are useful tools for evaluating the likelihood that a M dwarf terrestrial planet has a substantial atmosphere.
Youngblood, Allison, "Star Formation and Planets in Harsh Environments" (2017). Astrophysical & Planetary Sciences Graduate Theses & Dissertations. 61.