CASA fellows conduct research in astrophysical theory, observation, and instrumentation.  Research topics include exoplanets, stars, star formation, galaxies, black holes, and cosmology.

Tom Ayres

Tom Ayres

Senior Research Associate • Fellow
My group — which consists mainly of me — has been involved in a variety of mostly observational projects over the past five years, utilizing primarily Hubble Space Telescope and Chandra X-ray Observatory. During that period, I had two HST Large Treasury Projects — part of what is called the “Advanced Spectral Library,” an effort to collect the highest resolution, highest S/N UV spectral atlases with Space Telescope Imaging Spectrograph,...
John Bally

John Bally

Emeritus • Professor • Fellow
John Bally investigates the formation of stars, star clusters, and planetary systems using multii-wavelength observations with facilities such as HST, Spitzer, Herschel, ALMA, SOFIA, and a variety of ground based telescopes such as the VLA, Gemini, and the Apache Point Observatory. He uses observations of forming stars, protostellar outflows and jets, ionized nebulae, super-bubbles, and the interstellar medium to study how star formation is self-regulated by various feedback mechanisms.
Zach Berta-Thompson

Zach Berta-Thompson

Assistant Professor • Fellow
The Universe is teeming with planets; we now know of thousands of them orbiting stars other than our Sun. Zach Berta-Thompson observes transiting exoplanets -- those that pass in front of their stars as seen from Earth, resulting in periodic dimmings. Specializing in time-series photometry and spectroscopy with astronomical telescopes, Berta-Thompson searches for new transiting planets and studies the composition and dynamics of their atmospheres. By developing new observational techniques...
Alexander Brown

Alexander Brown

Senior Research Associate • Fellow
My research focuses of the physical conditions in the outer atmospheres (chromospheres and coronae) of late-type stars and how stellar magnetic activity and winds evolve over a stars' lifetime. These studies follow the atmospheric evolution from young newly-formed stars, to main-sequence dwarf stars, and into the giant and supergiant phases. I use a wide range of space-based observations (HST --- particularly in the ultraviolet; Chandra, XMM, and Swift for X-ray...
Jack Burns

Jack O Burns

Professor • Fellow • Emeritus
Observations and Cosmological Numerical Simulations of galaxy clusters and large scale structures, astrophysics from the Moon, theoretical modeling and space-based mission design for 21-cm observations of the first stars and black holes during the Dark Ages and Epoch of Reionization
Webster Cash

Webster Cash

Professor • Fellow
My research emphasizes the development and demonstration of new instrumentation for Space Astronomy. Right now I am working on Starshades, a technology I invented and have been championing for the last decade. NASA has now decided to seriously study and develop a starshade for flight in the coming decade with the goal of performing spectroscopy of habitable exoplanets. The Search for Life outside the Solar System!
Julie Comerford

Julie Comerford

Professor • Fellow
My research is on supermassive black holes, active galactic nuclei (AGN), and galaxy mergers. In particular I study AGN feeding and feedback, which includes AGN activation during galaxy mergers and AGN outflows influencing star formation in their host galaxies. To carry out this work, I use a suite of ground-based (APO, Keck, VLA) and space-based (Chandra, Hubble, WISE) telescopes.
Jeremy Darling

Jeremy Darling

Professor • Director • Fellow
My research involves black holes, cosmology, masers, astrometry, and fundamental physics. I have published papers on molecular masers, the galaxy-massive black hole connection, cosmology, gravitational lenses, astrometry and proper motions, secular redshift drift, water and formaldehyde in galaxies, telescope site survey work, hydrogen absorption, star formation, and the evolution (or not) of the fine structure constant, the electron-to-proton mass ratio, and the proton gyromagnetic factor. Current research includes primordial gravitational...
Erica Ellingson

Erica Ellingson

Emeritus • Associate Professor • Fellow
Observations of galaxy clusters and large-scale structures yield important constraints about dark matter and dark energy- mysterious components of the universe which govern its past evolution and its future. I study galaxies and galaxy clusters at multiple wavelengths to determine the interactions between galaxies, their large-scale environments, and the expanding universe. I also work on projects which engage undergraduate students in team research, including detecting explosive events in nearby galaxies...
Kevin France

Kevin France

Associate Professor • Fellow
In the past five years, the France research group has carried out observational and theoretical studies of stars and exoplanets while developing new hardware for future NASA UV/optical space astrophysics and planetary science missions. Dr. France was the science lead for the Hubble Space Telescope-COS Guaranteed Time Observing program’s protoplanetary disk, cool star, and exoplanet programs. He has since augmented that work with approximately a half-dozen Hubble guest observing programs...
James Green

James Green

Emeritus • Professor • Fellow
Space instrumentation development including the Cosmic Origins Spectrograph on the Hubble Space Telescope, the Far Ultraviolet Spectroscopic Explorer Spectrograph, and more than 20 years of sounding rocket payloads. Observational work on the physical conditions in the interstellar medium, the potential sources of intergalactic ionizing radiation, and theoretical work on the physical conditions in the pre-inflationary universe.
Nils Halverson

Nils Halverson

Professor • Fellow
Halverson develops millimeter-wavelength instrumentation to study the origins of the universe through observations of the Cosmic Microwave Background (CMB). Observations of the CMB can be used to gather evidence for gravitational waves released by an early period of inflation, and can be used to constrain the neutrino mass and the understand the growth of structure and dark energy. He is currently a co-investigator on two ground-based CMB experiments: the South...
Ben's photo

Benjamin Oppenheimer

Research Associate • Fellow
The Cosmic Origins Spectrograph (COS) is revealing a surprisingly complex and dynamic circumgalactic media surrounding the range of galaxies spanning Hubble tuning fork. I simulate galaxies and their galactic halos using cosmological hydrodynamical simulations. My students, collaborators, and I relate the gaseous signatures observed by COS to the dynamical processes of gas accretion, outflows, and hot halo formation that regulate galaxy growth and evolution. The thousands of orbits of COS...
Mike Shull

J Michael Shull

Emeritus • Professor • Fellow
My teaching and research interests in astrophysics include studies of galaxy formation, the ionizing continuum and broad emission lines of quasars, interstellar and intergalactic matter, supernova remnants, and the reionization epochs of hydrogen and helium in the high-redshift universe. My group carries out Hubble Space Telescope observations of the intergalactic medium, quasars, gamma-ray burst host galaxies, and high-redshift galaxies. I emphasize research on atomic, molecular, and radiative processes in astrophysics...
John Stocke

John Stocke

Emeritus • Professor • Fellow
John Stocke is an extragalactic observer who uses all manner of space-based and ground-based telescopes to study normal and active galaxies, clusters of galaxies, and intergalactic gas. I am also carrying out a project aimed at detecting changes in fundamental constants (e.g., fine-structure-constant and proton-to-electron mass ratio) with cosmic time. Recently my primary research interest has been in using the Hubble Space Telescope's spectrographs to discover, inventory, and study intergalactic...