Overview
My science interests focus on discovering and characterizing the atmospheres of directly imaging extrasolar planets around nearby stars, primarily with the Subaru Coronagraphic Extreme Adaptive Optics project (SCExAO) coupled with the CHARIS integral field spectrograph.
I also work on new instrumentation and new methods for image processing to better detect and extract spectra for exoplanets.
Longer-term, I am focused on directly imaging true solar system analogues, including habitable zone Earth-like exoplanets, with NASA missions like the Roman Space Telescope and Habitable Worlds Observatory and with 30m-class telescopes, such as the Thirty Meter Telescope and Giant Magellan Telescope.
I also work on new instrumentation and new methods for image processing to better detect and extract spectra for exoplanets.
Longer-term, I am focused on directly imaging true solar system analogues, including habitable zone Earth-like exoplanets, with NASA missions like the Roman Space Telescope and Habitable Worlds Observatory and with 30m-class telescopes, such as the Thirty Meter Telescope and Giant Magellan Telescope.
Exoplanet Direct Imaging Science
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The Subaru Coronagraphic Extreme Adaptive Optics Project
Now paired with the new 3000-actuator AO3k first-stage correction, the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) Project is a cutting-edge extreme adaptive optics (AO) platform combining a 2000-actuator deformable mirror, driven by a modulated Pyramid wavefront sensor at 2--3.5 kHz. It achieves high Strehl ratios (>80-90% at 1.65 microns) even for optically-faint stars inaccessible with other facilities. Coronagraph-suppressed starlight feeds instruments like the CHARIS integral field spectrograph, which delivers planet spectra across the JHK bands (1.1--2.4 microns) simultaneously. SCExAO/CHARIS is sensitive to young Jupiter-mass planets orbiting on solar system-like scales (5-30 au) around nearby young stars. Future upgrades to SCExAO will improve its planet discovery capabilities, approaching the performance needed to image some mature exoplanets in reflected light, and make it a critical testbed for technologies needed to image Earth-like exoplanets with future 30-40m class telescopes on the ground or NASA missions. My exoplanet direct imaging science interests with SCExAO focuses on two programs: 1. Imaging fully-formed exoplanets around stars showing evidence for the gravitational pull of an unseen planet from precision astrometry (accelerating stars) 2. Imaging planet formation: detecting actively-forming "protoplanets" directly and indirectly (through their influence on protoplanetary disk structure) |
(Top) SCExAO on the Nasmyth platform at Subaru. (Bottom) SCExAO/CHARIS images of the kappa And and HR 8799 planetary systems.
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Directly Imaging Planets Around Accelerating Stars
Departing from prior "unbiased" direct imaging survey approaches (e.g. GPIES), I target stars with SCExAO/CHARIS whose precision astrometry from the Hipparcos-Gaia Catalogue of Accelerations (HGCA) reveal dynamical evidence for an unseen planet. In a recent major paper in Science, I used SCExAO and HGCA to yield the first ever joint discovery of an extrasolar planet with direct imaging and astrometry: HIP 99770 b (Currie et al. 2023). Combining these two detection methods allows us to directly determine a planet's dynamical mass -- not possible with prior surveys -- and far better constrain planet orbits.
Departing from prior "unbiased" direct imaging survey approaches (e.g. GPIES), I target stars with SCExAO/CHARIS whose precision astrometry from the Hipparcos-Gaia Catalogue of Accelerations (HGCA) reveal dynamical evidence for an unseen planet. In a recent major paper in Science, I used SCExAO and HGCA to yield the first ever joint discovery of an extrasolar planet with direct imaging and astrometry: HIP 99770 b (Currie et al. 2023). Combining these two detection methods allows us to directly determine a planet's dynamical mass -- not possible with prior surveys -- and far better constrain planet orbits.
I now lead the 150-star Observing Accelerators with SCExAO Imaging Survey (OASIS), the largest active exoplanet direct imaging survey and the first large campaign specifically targeting accelerating stars. OASIS's approach promises to be far more efficient with discoveries than traditional ‘blind’ surveys like GPIES.
In one of two OASIS first results, we discovered a superjovian planet orbiting just 3--4 lambda/D from HIP 54515, a star never-before targeted for a planet search (Currie & Li et al. 2026, AJ, 171, 5).
OASIS will yield a sample of planets and brown dwarfs with precisely measured masses, orbits, and atmospheres. This well-characterized sample of substellar objects will shed new light on exoplanet and brown dwarf evolution and formation, by allowing us to 1) better calibrate luminosity evolution models, 2) constrain the atmospheric evolution of substellar objects as a function of mass, and 3) identify population-wide differences in the eccentricity distribution of planets and brown dwarfs that may be linked their formation history.
Key Strategic Support for the Roman Coronagraph -- OASIS focuses on primarily on bright stars and detecting self-luminous superjovian planets and brown dwarfs companions at 0.2"--0.5": exactly the targets needed for the Roman Coronagraph Technology Demonstration. OASIS's HIP 71618 B is the first demonstrably suitable target. Others (e.g. HIP 54515 b) can provide critical tests of instrument performance in the low-stellar-flux and small-separation limit, spectral retrieval, etc.
In one of two OASIS first results, we discovered a superjovian planet orbiting just 3--4 lambda/D from HIP 54515, a star never-before targeted for a planet search (Currie & Li et al. 2026, AJ, 171, 5).
OASIS will yield a sample of planets and brown dwarfs with precisely measured masses, orbits, and atmospheres. This well-characterized sample of substellar objects will shed new light on exoplanet and brown dwarf evolution and formation, by allowing us to 1) better calibrate luminosity evolution models, 2) constrain the atmospheric evolution of substellar objects as a function of mass, and 3) identify population-wide differences in the eccentricity distribution of planets and brown dwarfs that may be linked their formation history.
Key Strategic Support for the Roman Coronagraph -- OASIS focuses on primarily on bright stars and detecting self-luminous superjovian planets and brown dwarfs companions at 0.2"--0.5": exactly the targets needed for the Roman Coronagraph Technology Demonstration. OASIS's HIP 71618 B is the first demonstrably suitable target. Others (e.g. HIP 54515 b) can provide critical tests of instrument performance in the low-stellar-flux and small-separation limit, spectral retrieval, etc.
Imaging Planet Formation
I use SCExAO/CHARIS in total and polarized light and other instruments sensitive to accretion to resolve planet-forming disks around young stars of a range of masses to reveal evidence of growing protoplanets from the disks' structures or even the protoplanets themselves. In 2022, I discovered AB Aurigae b, a concentrated emission source consistent with a massive wide-separation protoplanet embedded in a disk. Follow-up integral field polarimetry led by my PhD student Erica Dykes and H-alpha medium resolution spectroscopy probed indirect signatures of planet formation in the disk and identified a signal consistent with accretion onto AB Aur b.
I am a core team member of a large SCExAO survey (PI: J. Hashimoto) targeting young low-mass stars whose disks show planet-induced structures, while my student Erica Dykes and I lead a complementary program around young Sun-like stars with ALMA-identified sculpted disks. Both projects resolve 10--30 au scales to directly image forming planets, planet-induced structures and provide the first systematic census of protoplanets across stellar masses, enabling empirical tests of competing formation theories.
I use SCExAO/CHARIS in total and polarized light and other instruments sensitive to accretion to resolve planet-forming disks around young stars of a range of masses to reveal evidence of growing protoplanets from the disks' structures or even the protoplanets themselves. In 2022, I discovered AB Aurigae b, a concentrated emission source consistent with a massive wide-separation protoplanet embedded in a disk. Follow-up integral field polarimetry led by my PhD student Erica Dykes and H-alpha medium resolution spectroscopy probed indirect signatures of planet formation in the disk and identified a signal consistent with accretion onto AB Aur b.
I am a core team member of a large SCExAO survey (PI: J. Hashimoto) targeting young low-mass stars whose disks show planet-induced structures, while my student Erica Dykes and I lead a complementary program around young Sun-like stars with ALMA-identified sculpted disks. Both projects resolve 10--30 au scales to directly image forming planets, planet-induced structures and provide the first systematic census of protoplanets across stellar masses, enabling empirical tests of competing formation theories.
Exoplanet Direct Imaging Instrumentation and Data Analysis
Exoplanet Imaging Instrumentation and Wavefront Control Advances
Instrumentation Development at EGRET - Led by my postdoc Mona El Morsy, at UTSA I am developing the ExplorinG Research on Exoplanets and Technology (EGRET) high-contrast imaging laboratory. My goal is to use the laboratory, time on the SCExAO optical bench, and on-sky testing with SCExAO to explore and hone new instrumentation advances and wavefront control algorithms that will be needed to someday image solar system-like planets in reflected light using ground-based telescopes. In 2026, EGRET will focus on two projects: Exo-NINJA -- a fiber-fed medium resolution spectrograph -- and the Thermal Phase Shifter–GLINT. See papers here and here.
Wavefront control - I am interested in advanced wavefront sensing capabilities that will be critical to the success of exoplanet imaging in space and on the ground. I conducted experiments further developing a new high-contrast wavefront control method called "Linear Dark Field Control", which LDFC corrects for changes in the "dark field" (deep contrast region within which we can image planets) by measuring corresponding intensity changes within the "bright field" (uncorrected region). The consequences should be dramatic: LDFC will increase direct imaging contrast and sensitivity, allowing us to discover and characterize lower mass, more solar system-like exoplanets. Read more about LDFC here and see our first paper demonstrating LDFC at contrasts relevant for imaging extrasolar planets in reflected light here. More recently, we have proposed a test of LDFC as a part of the Roman Coronagraph technology demonstration phase: see here.
Instrumentation Development at EGRET - Led by my postdoc Mona El Morsy, at UTSA I am developing the ExplorinG Research on Exoplanets and Technology (EGRET) high-contrast imaging laboratory. My goal is to use the laboratory, time on the SCExAO optical bench, and on-sky testing with SCExAO to explore and hone new instrumentation advances and wavefront control algorithms that will be needed to someday image solar system-like planets in reflected light using ground-based telescopes. In 2026, EGRET will focus on two projects: Exo-NINJA -- a fiber-fed medium resolution spectrograph -- and the Thermal Phase Shifter–GLINT. See papers here and here.
Wavefront control - I am interested in advanced wavefront sensing capabilities that will be critical to the success of exoplanet imaging in space and on the ground. I conducted experiments further developing a new high-contrast wavefront control method called "Linear Dark Field Control", which LDFC corrects for changes in the "dark field" (deep contrast region within which we can image planets) by measuring corresponding intensity changes within the "bright field" (uncorrected region). The consequences should be dramatic: LDFC will increase direct imaging contrast and sensitivity, allowing us to discover and characterize lower mass, more solar system-like exoplanets. Read more about LDFC here and see our first paper demonstrating LDFC at contrasts relevant for imaging extrasolar planets in reflected light here. More recently, we have proposed a test of LDFC as a part of the Roman Coronagraph technology demonstration phase: see here.
Image Processing
To directly image planets, I've built an exoplanet direct imaging pipeline including advanced PSF subtraction techniques called ``adaptive" LOCI or A-LOCI. A-LOCI is a sort of 'hybrid' of the Locally Optimized Combination of Images (LOCI) and Karhunen-Lo'eve Eigen-Images Projection (KLIP) algorithms. It employs ``speckle filtering" (`on-the-fly' correlation-based frame selection), a moving pixel mask and a varying SVD cutoff to model individual modes of speckle noise structure, etc. As a result, it often achieves deeper contrast than LOCI or KLIP methods. Equally important, A-LOCI now provides much better precision in extracting useful planet spectra and astrometry, through forward modeling. I plan to incorporate more wrinkles into this approach in the future.
Papers describing A-LOCI PSF subtraction and forward-modeling are here, here, and here.
To directly image planets, I've built an exoplanet direct imaging pipeline including advanced PSF subtraction techniques called ``adaptive" LOCI or A-LOCI. A-LOCI is a sort of 'hybrid' of the Locally Optimized Combination of Images (LOCI) and Karhunen-Lo'eve Eigen-Images Projection (KLIP) algorithms. It employs ``speckle filtering" (`on-the-fly' correlation-based frame selection), a moving pixel mask and a varying SVD cutoff to model individual modes of speckle noise structure, etc. As a result, it often achieves deeper contrast than LOCI or KLIP methods. Equally important, A-LOCI now provides much better precision in extracting useful planet spectra and astrometry, through forward modeling. I plan to incorporate more wrinkles into this approach in the future.
Papers describing A-LOCI PSF subtraction and forward-modeling are here, here, and here.
Keck/NIRC2 data for HR 8799 reduced with three different methods: (left) a 'classical' ADI-based PSF subtraction method, (middle) LOCI, and (right) A-LOCI. LOCI and (especially) A-LOCI yield a significant contrast gain, allowing us to image faint planets deeply embedded in the stellar halo.