I'm an observational astronomer and instrumentalist with an interest in planet formation and evolution. My group’s research ranges from high resolution observations of young stars, to interferometric imaging and data reduction techniques, to the design and construction of next-generation instruments for observatories such as Keck.
Observational Planet Formation
Constraining the detailed physics of planet formation requires directly characterizing forming planets themselves, along with the dusty environments around young stars. Doing this for Solar System scales is very difficult given the large distances to star forming regions. My group applies interferometric techniques on the world’s largest ground-based telescopes (Keck, Subaru, LBT) to image ~5-10 AU scales around distant young stars. This allows us to identify companion candidates as well as complex disk structures indicating ongoing planet formation. (Check back here soon for more updates on Keck/NIRC2 studies of young stars!)
Recently we’ve also been involved in identifying optimal hydrogen lines for tracing shocked gas falling onto actively forming planets.
From Sallum et al. 2019. Image reconstructed from multi-epoch Keck/NIRC2 aperture masking observations of the young star SR 21 (left), compared to simulated reconstructions for a disk with a warp at ~3-5 AU (right). These data showed that the small grain disk morphology doesn’t match the one observed in mm grains with ALMA. The warp / spiral structure could be explained by the gravitational influence of actively-forming planets.
From Sallum et al. 2021. A model-independent image of a companion candidate (a) and an outflow cavity (b) around the Be star MWC 297. This image was reconstructed from aperture masking observations taken using the actively co-phased Large Binocular Telescope Interferometer.
Developing Interferometric Imaging Techniques
From Doelman et al. 2021. Images of a holographic aperture mask showing the liquid crystal phase patterns that move light in the focal plane. We recently demonstrated HAM for the first time using Keck/OSIRIS, and are working on upgrading that optic.
Pushing the capabilities of existing instruments to maximize effective resolution requires advances in both optics and data processing techniques. My group works in both of these areas for ground and space-based observing facilities.
As members of a James Webb Space Telescope Early Release Science program, we have developed data reduction tools for JWST/NIRISS AMI observations (available on github) and are currently characterizing NIRISS’ achievable contrast in this mode. We also recently demonstrated the technique of dispersed kernel phase interferometry for the first time using the CHARIS integral field spectrograph on Subaru / SCExAO. We are also involved in pushing angular resolution using optics such as holographic aperture masks as well as photonic lanterns.
Instrumentation
Adapted from Briesemeister, Sallum et al. 2020. Post-processed end to end simulation SCALES observations of an HR 8799-like planetary system. SCALES will directly detect and characterize systems such as these, and will enable us to perform similar observations for planets as cold as 300 K.
I am the Project Scientist for the Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES), a 2-5 µm integral field spectrograph currently being built for Keck Observatory. SCALES is designed specifically for simultaneous detection and characterization of colder exoplanets than those we can currently image and characterize. My group is actively involved in SCALES simulation and design work, hardware development, and early science planning. We were recently awarded a Track 2 NSF MRI to fund SCALES’ construction, and we are on track for first light in 2025!
Beyond SCALES, I am leading the development of science cases and requirements for the Thirty Meter Telescope Planetary Systems Imager instrument concept. I’m also an active contributor on a handful of other instrumentation projects, including Keck’s KAPA and HAKA adaptive optics upgrades.