Bio/Contact

Email: dkpowell AT ucsc DOT edu

I’m a second year PhD student in Astrophysics at UC Santa Cruz and I am particularly interested in exoplanet formation, planetary atmospheres and solar system dynamics. I work with Prof. Xi Zhang and Prof. Ruth Murray-Clay. I graduated from Harvard in 2014 with a BA in Astrophysics & Physics and spent a year traveling throughout Asia.

When I’m not doing research you can find me hiking in the Californian outdoors, experimenting in the kitchen, or lounging about with great tea and good books.

Research

Formation of Clouds and Hazes on Tidally Locked Exoplanets: Insights From Size Distribution Dynamics

I currently work with Prof. Xi Zhang to constrain cloud formation on tidally locked exoplanets using a 1d microphysical code (CARMA) to model clouds parameters from first principles. This code is particularly powerful as we can uncover the true size distribution of cloud particles and determine their effect on observables with few assumptions.

Using Ice and Dust Lines to Constrain the Surface Densities of Protoplanetary Disks

I currently work with Prof. Ruth Murray-Clay to determine the surface density of protoplanetary disks through the consideration of of disk ‘dust lines’ which indicate the observed disk radial scale at different observational wavelengths. We provide an initial proof of concept of our model through an application to the disk TW Hydra and are able to estimate the disk dust-to-gas ratio, CO abundance, and accretion rate in addition to the total disk surface density. We find that our derived surface density profile and dust-to-gas ratio are consistent with the lower limits found through measurements of the HD gas that our theoretical CO ice line estimates have clear observational analogues.

Explosion Parameters of SN 2013df and Properties of Its Progenitor Star

I worked with Prof. Alicia Soderberg on my senior thesis which focused on the UV - optical characterization of the type IIb SN 2013df. Type IIb supernovae represent a transitional type between Type II and Type Ib supernovae. Only 6 Type IIb supernovae have been observationally studied and theoretical work has not yet been able to fully understand the stellar progenitors. My thesis constrains properties of the progenitor star and gives explosion parameters of SN2013df.

The Influence of Bars in Triggering Star Formation Since z=1

I worked with Dr. Kartik Sheth and Dr. Kim Scott at the NRAO on the influence of galactic bars in triggering star formation since a redshift of 1. With this project I characterized the complex effects of a changing fraction of barred spiral galaxies on the global star formation rate for the second half of the universe’s age.

Characterizing New Transitional Disks in the Taurus Star Forming Region

I worked with Prof. Catherine Espaillat on my junior thesis that investigated circumstellar transitional disks (disks with holes) in the sub-millimeter range around newly discovered T Tauri stars in the Taurus and Ophiuchus star forming regions. The modeling done in this project allowed us to place constraints on the physical structure of these disks, which can be used to better understand how planets form.

Publications

Powell, D., Murray-Clay, R., & Schlichting, H.E., 2017, “Using Ice and Dust Lines to Constrain the Surface Densities of Protoplanetary Disks”

Espaillat, C., Andrews, S., Powell, D., et al. 2015, “The Transitional Disk around IRAS 04125+2902”

Kamble, A., Margutti, R., Soderberg, A. M., et al. inc. Powell, D. 2015, “Radio and X-rays From SN 2013df Enlighten Progenitors of Type IIb Supernovae”

Soderberg, A. et al. inc. Powell, D. 2012, The Astronomer’s Telegram, 3968, 1, “Spectroscopic Classification of the SN in NGC 4790”

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