Benjamin L. Gerard
A5047354924- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Astronomy and Astrophysical Research
- Optical Systems and Laser Technology
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Advanced optical system design
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Optical Wireless Communication Technologies
- Calibration and Measurement Techniques
- Advanced Optical Sensing Technologies
- Optical Coherence Tomography Applications
- History and Developments in Astronomy
- Scientific Research and Discoveries
- Astrophysical Phenomena and Observations
- Spectroscopy and Laser Applications
- Advanced Measurement and Metrology Techniques
- Atmospheric Ozone and Climate
- Photoacoustic and Ultrasonic Imaging
- Medical Imaging Techniques and Applications
- Optical properties and cooling technologies in crystalline materials
- Space exploration and regulation
- CCD and CMOS Imaging Sensors
- Infrared Target Detection Methodologies
Lawrence Livermore National Laboratory
2023-2024
Herzberg Institute of Astrophysics
2015-2023
University of Victoria
2015-2023
University of California, Santa Cruz
2020-2023
National Research Council Canada
2016-2020
California Institute of Technology
2019
Kavli Institute for Particle Astrophysics and Cosmology
2019
Space Telescope Science Institute
2019
National Academies of Sciences, Engineering, and Medicine
2018
Laboratory for Atmospheric and Space Physics
2016
Abstract We present a statistical analysis of the first 300 stars observed by Gemini Planet Imager Exoplanet Survey. This subsample includes six detected planets and three brown dwarfs; from these detections our contrast curves we infer underlying distributions substellar companions with respect to their mass, semimajor axis, host stellar mass. uncover strong correlation between planet occurrence rate star M * > 1.5 ⊙ more likely masses 2 13 Jup axes 3–100 au at 99.92% confidence. fit...
An exoplanet extracted from the bright Direct imaging of Jupiter-like exoplanets around young stars provides a glimpse into how our solar system formed. The brightness requires use next-generation devices such as Gemini Planet Imager (GPI). Using GPI, Macintosh et al. discovered planet orbiting star, 51 Eridani (see Perspective by Mawet). planet, Eri b, has methane signature and is probably smallest that been directly imaged. These findings open door to understanding origins herald dawn new...
We present a new matched filter algorithm for direct detection of point sources in the immediate vicinity bright stars. The stellar Point Spread Function (PSF) is first subtracted using Karhunen-Lo\'eve Image Processing (KLIP) with Angular and Spectral Differential Imaging (ADI SDI). KLIP-induced distortion astrophysical signal included template by computing forward model PSF at every position image. To optimize performance algorithm, we conduct extensive planet injection recovery tests tune...
Two studies utilizing sparse aperture masking (SAM) interferometry and $H_{\rm \alpha}$ differential imaging have reported multiple jovian companions around the young solar-mass star, LkCa 15 (LkCa bcd): first claimed direct detection of infant, newly-formed planets ("protoplanets"). We present new near-infrared imaging/spectroscopy from SCExAO system coupled with CHARIS integral field spectrograph multi-epoch thermal infrared Keck/NIRC2 at high Strehl ratios. These data provide look same...
Abstract We report the results of a ∼4 yr direct imaging survey 104 stars to resolve and characterize circumstellar debris disks in scattered light as part Gemini Planet Imager (GPI) Exoplanet Survey. targeted nearby (≲150 pc), young (≲500 Myr) with high infrared (IR) excesses ( L IR / ⋆ > 10 −5 ), including 38 previously resolved disks. Observations were made using GPI high-contrast integral field spectrograph H -band (1.6 μ m) coronagraphic polarimetry mode measure both polarized total...
The HR 8799 system uniquely harbors four young super-Jupiters whose orbits can provide insights into the system's dynamical history and constrain masses of planets themselves. Using Gemini Planet Imager (GPI), we obtained down to one milliarcsecond precision on astrometry these planets. We assessed four-planet orbit models with different levels constraints found that assuming are near 1:2:4:8 period commensurabilities, or coplanar, does not worsen fit. added prior must have been stable for...
We explore KLIP forward modeling spectral extraction on Gemini Planet Imager coronagraphic data of HR 8799, using PyKLIP and show algorithm stability with varying parameters. report new re-reduced spectrophotometry 8799 c, d, e in H & K bands. discuss a strategy for choosing optimal PSF subtraction parameters by injecting simulated sources recovering them over range The K1/K2 spectra c d are similar to previously published results from the same dataset. also present band spectrum first time...
We present the first scattered-light image of debris disk around HD 131835 in H band using Gemini Planet Imager. is a ∼15 Myr old A2IV star at distance ∼120 pc Sco-Cen OB association. detect only polarized light and place an upper limit on peak total intensity. No point sources resembling exoplanets were identified. Compared to its mid-infrared thermal emission, scattered shows similar orientation but different morphology. The extends from ∼75 ∼210 AU plane with roughly flat surface density....
We present evidence that the recently discovered, directly-imaged planet HD 131399 Ab is a background star with non-zero proper motion. From new JHK1L' photometry and spectroscopy obtained Gemini Planet Imager, VLT/SPHERE, Keck/NIRC2, reanalysis of discovery data we derive colors, spectra, astrometry for Ab. The broader wavelength coverage higher quality allow us to re-investigate its status. Its near-infrared spectral energy distribution excludes types later than L0 consistent K or M dwarf,...
We present new $H$ (1.5-1.8 $\mu$m) photometric and $K_1$ (1.9-2.2 spectroscopic observations of the young exoplanet HD 95086 b obtained with Gemini Planet Imager. The $H$-band magnitude has been significantly improved relative to previous measurements, whereas low resolution ($\lambda/\delta\lambda \approx 66$) spectrum is featureless within measurement uncertainties, presents a monotonically increasing pseudo-continuum consistent cloudy atmosphere. By combining these measurements...
We present new Gemini Planet Imager observations of the young exoplanet 51 Eridani b that provide further evidence companion is physically associated with Eridani. Combining this astrometric measurement those reported in literature, we significantly reduce posterior probability an unbound foreground or background T-dwarf a chance alignment to 2 × 10−7, order magnitude lower than previously reported. If indeed bound object, then have detected orbital motion planet between discovery epoch and...
Abstract We have obtained Hubble Space Telescope STIS and NICMOS Gemini /GPI scattered-light images of the HD 191089 debris disk. identify two spatial components: a ring resembling Kuiper Belt in radial extent (FWHM ∼ 25 au, centered at ∼46 au) halo extending to ∼640 au. find that is significantly bluer than ring, consistent with scenario serves as “birth ring” for smaller dust halo. measure scattering phase functions 30°–150° scattering-angle range more forward- backward-scattering dust....
Abstract HR4796A hosts a well-studied debris disk with long history due to its high fractional luminosity and favorable inclination, which facilitate both unresolved resolved observations. We present new J - K 1 -band images of the taken in polarimetric mode Gemini Planet Imager (GPI). The polarized intensity features strongly forward-scattered brightness distribution is undetected at far side disk. total detected all scattering angles also exhibits strong forward-scattering peak. use...
Using the Gemini Planet Imager (GPI), we have resolved circumstellar debris disk around HD 111520 at a projected range of ~30-100 AU in both total and polarized $H$-band intensity. The is seen edge-on position angle ~165$^{\circ}$ along spine emission. A slight inclination or asymmetric warping are covariant alters interpretation observed We employ 3 point spread function (PSF) subtraction methods to reduce stellar glare instrumental artifacts confirm that there roughly 2:1 brightness...
We present a new algorithm for space telescope high contrast imaging of close-to-face-on planetary disks called Optimized Spatially Filtered (OSFi) normalization. This is used on HR 8799 Hubble Space Telescope (HST) coronagraphic archival data, showing an over-luminosity after reference star point spread function (PSF) subtraction that may be from the inner disk and/or planetesimal belt components this system. The PSF-subtracted radial profiles in two separate epochs 2011 and 2012 are...
We present $H$-band near-infrared polarimetric imaging observations of the F5V star HD~157587 obtained with Gemini Planet Imager (GPI) that reveal debris disk as a bright ring structure at separation $\sim$80$-$100~AU. The new GPI data complement recent HST/STIS show extending out to over 500~AU. image displays strong asymmetry along projected minor axis well fainter major axis. associate and asymmetries polarized forward scattering possible stellocentric offset, respectively. To constrain...
We present a revision to the visual orbit of young, directly-imaged exoplanet 51 Eridani b using four years observations with Gemini Planet Imager. The relative astrometry is consistent an eccentric ($e=0.53_{-0.13}^{+0.09}$) at intermediate inclination ($i=136_{-11}^{+10}$\,deg), although circular orbits cannot be excluded due complex shape multidimensional posterior distribution. find semi-major axis $11.1_{-1.3}^{+4.2}$\,au and period $28.1_{-4.9}^{+17.2}$\,yr, assuming mass...
We present new $H$-band scattered light images of the HD 32297 edge-on debris disk obtained with Gemini Planet Imager (GPI). The is detected in total and polarized intensity down to a projected angular separation 0.15", or 20au. On other hand, large scale swept-back halo remains undetected, likely consequence its markedly blue color relative parent body belt. analyze curvature spine estimate radius $\approx$100au for belt, smaller than past studies but consistent thermal emission maps...
Direct imaging and spectral characterization of exoplanets using extreme adaptive optics (ExAO) is a key science goal future extremely large telescopes space observatories. However, quasi-static wavefront errors will limit the sensitivity this endeavor. Additional limitations for ground-based arise from residual AO-corrected atmospheric errors, generating millisecond-lifetime speckles that average into halo over long exposure. A solution to both these problems use camera an ExAO system as...
Abstract We present new near-infrared Gemini Planet Imager (GPI) spectroscopy of HD 206893 B, a substellar companion orbiting within the debris disk its F5V star. The J , H K1 and K2 spectra from GPI demonstrate extraordinarily red colors object, confirming it as reddest object observed to date. significant flux increase throughout infrared presents challenging atmosphere model with existing grids. Best-fit values vary 1200 1800 K for effective temperature 3.0 5.0 log( g ), depending on...
We present new observations of the planet beta Pictoris b from 2018 with GPI, first GPI following conjunction. Based on these measurements, we perform a joint orbit fit to available relative astrometry ground-based imaging, Hipparcos Intermediate Astrometric Data (IAD), and Gaia DR2 position, demonstrate how incorporate IAD into direct imaging fits. find mass consistent predictions hot-start evolutionary models previous works similar methods, though larger uncertainties: 12.8 [+5.3, -3.2]...
We present a revision to the astrometric calibration of Gemini Planet Imager (GPI), an instrument designed achieve high contrast at small angular separations necessary image substellar and planetary-mass companions around nearby, young stars. identified several issues with GPI data reduction pipeline (DRP) that significantly affected determination angle north in reduced images. As well as introducing error position measurements for targets observed zenith distances, this led significant...
The Santa Cruz Extreme AO Lab (SEAL) is a new visible-wavelength testbed designed to advance the state of art in wavefront control for high contrast imaging on large, segmented, ground-based telescopes. SEAL provides multiple options simulating atmospheric turbulence, including custom spatial light modulator. A 37-segment deformable mirror simulates W. M. Keck Observatory segmented primary mirror. adaptive optics system consists woofer/tweeter DM system, and four sensor arms: 1) high-speed...
Abstract We present the first polarimetric detection of inner disk component around pre-main-sequence B9.5 star HD 141569A. Gemini Planet Imager H -band (1.65 μ m) differential imaging reveals highest signal-to-noise ratio this ring yet attained and traces structure inward to 0.″25 (28 au at a distance 111 pc). The radial polarized intensity image shows east side disk, peaking in 0.″40 (44 au) extending out 0.″9 (100 au). There is spiral arm–like enhancement south, reminiscent known...
Facility-class high-contrast exoplanet imaging systems are currently limited by non-common path quasi-static speckles. Due to these aberrations, the raw contrast saturates after a few seconds. Several active wavefront correction techniques have been developed remove this noise, with success. The NRC Canada is funding two projects, SPIDERS pathfinder at Subaru telescope (ETA 2023), and CAL2 upgrade of Gemini Planet Imager-2 2024), deploy modified self-coherent camera (based on FAST) measure...