Showing papers by "James R. Graham published in 2017"
Arizona State University1, Université de Montréal2, University of California, Berkeley3, Ames Research Center4, Stanford University5, University of Victoria6, National Research Council7, Harvard University8, Space Telescope Science Institute9, Los Alamos National Laboratory10, Lawrence Livermore National Laboratory11, University of California, Los Angeles12, University of Arizona13, National Institutes of Natural Sciences, Japan14, Princeton University15, University of Toronto16, University of Georgia17, University of Grenoble18, University of California, Santa Cruz19, University of Michigan20, Search for extraterrestrial intelligence21, University of California, San Diego22, University of Western Ontario23, Stony Brook University24, California Institute of Technology25, American Museum of Natural History26, Cornell University27, The Aerospace Corporation28, Johns Hopkins University29
TL;DR: In this paper, the authors proposed a method to detect exoplanets using the ESI program for GPI related to NASA's Exoplanets Research Program (XRP) and NExSS (NExSS).
Abstract: NSF [AST1411868, AST-1518332, DGE-1311230]; NASA [NNX14AJ80G]; Fonds de Recherche du Quebec; NASA Exoplanets Research Program (XRP) [NNX16AD44G]; JPL's ESI program for GPIrelated; NASA's Science Mission Directorate; NExSS [NNX15AD95G]; U.S. Department of Energy by Lawrence Livermore National Laboratory [DE-AC52-07NA27344]
137 citations
University of Cambridge1, Harvard University2, University of California, Berkeley3, Search for extraterrestrial intelligence4, University of Grenoble5, Wesleyan University6, Massachusetts Institute of Technology7, Pennsylvania State University8, Goddard Space Flight Center9, University of California, Los Angeles10, UK Astronomy Technology Centre11, University of Leeds12, University of Arizona13
TL;DR: Matra et al. as discussed by the authors used spectrospatial filtering to detect CO J = 2-1 emission colocated with dust emission from the cometary belt in the 440 Myr old Fomalhaut system.
Abstract: Author(s): Matra, L; MacGregor, MA; Kalas, P; Wyatt, MC; Kennedy, GM; Wilner, DJ; Duchene, G; Hughes, AM; Pan, M; Shannon, A; Clampin, M; Fitzgerald, MP; Graham, JR; Holland, WS; Panic, O; Su, KYL | Abstract: Recent Atacama Large Millimeter/submillimeter Array observations present mounting evidence for the presence of exocometary gas released within Kuiper Belt analogs around nearby main-sequence stars. This represents a unique opportunity to study their ice reservoir at the younger ages when volatile delivery to planets is most likely to occur. We here present the detection of CO J = 2-1 emission colocated with dust emission from the cometary belt in the 440 Myr old Fomalhaut system. Through spectrospatial filtering, we achieve a 5.4σ detection and determine that the ring's sky-projected rotation axis matches that of the star. The CO mass derived ((0.65-42) × 10-7 M⊕) is the lowest of any circumstellar disk detected to date and must be of exocometary origin. Using a steady-state model, we estimate the CO+CO2 mass fraction of exocomets around Fomalhaut to be between 4.6% and 76%, consistent with solar system comets and the two other belts known to host exocometary gas. This is the first indication of a similarity in cometary compositions across planetary systems that may be linked to their formation scenario and is consistent with direct interstellar medium inheritance. In addition, we find tentative evidence that (49 ± 27)% of the detected flux originates from a region near the eccentric belt's pericenter. If confirmed, the latter may be explained through a recent impact event or CO pericenter glow due to exocometary release within a steady-state collisional cascade. In the latter scenario, we show how the azimuthal dependence of the CO release rate leads to asymmetries in gas observations of eccentric exocometary belts.
112 citations
TL;DR: In this paper, the authors presented spectro-photometry spanning 1-5$m of 51 Eridani b, a 2-10 M$_\text{Jup}$ planet discovered by the Gemini Planet Imager Exoplanet Survey.
Abstract: We present spectro-photometry spanning 1-5 $\mu$m of 51 Eridani b, a 2-10 M$_\text{Jup}$ planet discovered by the Gemini Planet Imager Exoplanet Survey. In this study, we present new $K1$ (1.90-2.19 $\mu$m) and $K2$ (2.10-2.40 $\mu$m) spectra taken with the Gemini Planet Imager as well as an updated $L_P$ (3.76 $\mu$m) and new $M_S$ (4.67 $\mu$m) photometry from the NIRC2 Narrow camera. The new data were combined with $J$ (1.13-1.35 $\mu$m) and $H$ (1.50-1.80 $\mu$m) spectra from the discovery epoch with the goal of better characterizing the planet properties. 51 Eri b photometry is redder than field brown dwarfs as well as known young T-dwarfs with similar spectral type (between T4-T8) and we propose that 51 Eri b might be in the process of undergoing the transition from L-type to T-type. We used two complementary atmosphere model grids including either deep iron/silicate clouds or sulfide/salt clouds in the photosphere, spanning a range of cloud properties, including fully cloudy, cloud free and patchy/intermediate opacity clouds. Model fits suggest that 51 Eri b has an effective temperature ranging between 605-737 K, a solar metallicity, a surface gravity of $\log$(g) = 3.5-4.0 dex, and the atmosphere requires a patchy cloud atmosphere to model the SED. From the model atmospheres, we infer a luminosity for the planet of -5.83 to -5.93 ($\log L/L_{\odot}$), leaving 51 Eri b in the unique position as being one of the only directly imaged planet consistent with having formed via cold-start scenario. Comparisons of the planet SED against warm-start models indicates that the planet luminosity is best reproduced by a planet formed via core accretion with a core mass between 15 and 127 M$_{\oplus}$.
97 citations
University of Toronto1, Space Telescope Science Institute2, University of California, Berkeley3, Stanford University4, University of Arizona5, Lawrence Livermore National Laboratory6, University of Western Ontario7, National Institutes of Natural Sciences, Japan8, Princeton University9, University of Georgia10, University of California, Santa Cruz11, Université de Montréal12, National Research Council13, University of Victoria14, University of Grenoble15, University of California, Los Angeles16, Durham University17, University of Michigan18, European Southern Observatory19, Search for extraterrestrial intelligence20, University of California, San Diego21, Ames Research Center22, California Institute of Technology23, American Museum of Natural History24, Arizona State University25, Universities Space Research Association26, Cornell University27, The Aerospace Corporation28, Johns Hopkins University29
TL;DR: Gemini Observatory, Dunlap Institute, University of Toronto, NSF Center for Adaptive Optics at UC Santa Cruz; NSF [AST-0909188], AST-1211562, AST-1405505] as mentioned in this paper.
Abstract: Gemini Observatory; Dunlap Institute, University of Toronto; NSF Center for Adaptive Optics at UC Santa Cruz; NSF [AST-0909188, AST-1211562, AST-1405505]; NASA Origins [NNX11AD21G, NNX10AH31G, NNX14AC21G, NNX15AC89G]; NASA NExSS [NNX15AD95G]; University of California Office of the President [LFRP-118057]; Science and Technology Facilities Council [ST/H002707/1]; U.S. Department of Energy by Lawrence Livermore National Laboratory [DE-AC52-07NA27344]; California Institute of Technology/Jet Propulsion Laboratory - NASA through Sagan Fellowship Program; NASA Exoplanets Research Program (XRP) [NNX16AD44G]; NASA through Hubble Fellowship - Space Telescope Science Institute [51378.01-A]; NASA [NAS5-26555]; NASAs Science Mission Directorate
97 citations
TL;DR: In this article, the authors used spectro-spatial filtering to detect CO J = 2-1 emission co-located with dust emission from the cometary belt in the 440 Myr-old Fomalhaut system.
Abstract: Recent ALMA observations present mounting evidence for the presence of exocometary gas released within Kuiper belt analogues around nearby main sequence stars. This represents a unique opportunity to study their ice reservoir at the younger ages when volatile delivery to planets is most likely to occur. We here present the detection of CO J=2-1 emission co-located with dust emission from the cometary belt in the 440 Myr-old Fomalhaut system. Through spectro-spatial filtering, we achieve a 5.4$\sigma$ detection and determine that the ring's sky-projected rotation axis matches that of the star. The CO mass derived ($0.65-42 \times10^{-7}$ M$_{\oplus}$) is the lowest of any circumstellar disk detected to date, and must be of exocometary origin. Using a steady state model, we estimate the CO+CO$_2$ mass fraction of exocomets around Fomalhaut to be between 4.6-76%, consistent with Solar System comets and the two other belts known to host exocometary gas. This is the first indication of a similarity in cometary compositions across planetary systems that may be linked to their formation scenario and is consistent with direct ISM inheritance. In addition, we find tentative evidence that $(49\pm 27)$% of the detected flux originates from a region near the eccentric belt's pericentre. If confirmed, the latter may be explained through a recent impact event or CO pericentre glow due to exocometary release within a steady state collisional cascade. In the latter scenario, we show how the azimuthal dependence of the CO release rate leads to asymmetries in gas observations of eccentric exocometary belts.
95 citations
Université de Montréal1, Stanford University2, Amherst College3, Space Telescope Science Institute4, University of Victoria5, National Research Council6, California Institute of Technology7, University of California, Berkeley8, Search for extraterrestrial intelligence9, University of Toronto10, University of Arizona11, Stony Brook University12, University of Western Ontario13, Johns Hopkins University14, Lawrence Livermore National Laboratory15, Subaru16, University of Georgia17, University of Grenoble18, University of California, Los Angeles19, Durham University20, University of Michigan21, European Southern Observatory22, University of California, San Diego23, American Museum of Natural History24, Arizona State University25, Ames Research Center26, Cornell University27, The Aerospace Corporation28
TL;DR: In this paper, the authors used the Sagan Fellowship Program to train a team of researchers at the Lawrence Livermore National Laboratory (LNL) in order to conduct experiments on the Mars Curiosity rover.
Abstract: DPAC; Fonds de Recherche du Quebec; NASA through the Sagan Fellowship Program; NSF [AST-1411868, AST-141378]; NASA [NNX14AJ80G, NNX15AD95G, NNX16AD44G]; U.S. Department of Energy by the Lawrence Livermore National Laboratory [DE-AC52-07NA27344]
83 citations
University of Toronto1, Space Telescope Science Institute2, University of California, Berkeley3, Stanford University4, University of Arizona5, Lawrence Livermore National Laboratory6, University of Western Ontario7, Subaru8, Princeton University9, University of Georgia10, University of California, Santa Cruz11, Université de Montréal12, National Research Council13, University of California, Los Angeles14, University of Michigan15, European Southern Observatory16, University of California, San Diego17, Search for extraterrestrial intelligence18, Ames Research Center19, American Museum of Natural History20, Arizona State University21, Universities Space Research Association22, Cornell University23, California Institute of Technology24, The Aerospace Corporation25, Johns Hopkins University26
TL;DR: In this paper, the Gemini Planet Imager (GPI) was used to measure the near-infrared (1.0-2.4 micron) spectrum of the planetary companion to the nearby, young star Pictoris.
Abstract: Using the Gemini Planet Imager (GPI) located at Gemini South, we measured the near-infrared (1.0-2.4 micron) spectrum of the planetary companion to the nearby, young star $\beta$ Pictoris. We compare the spectrum obtained with currently published model grids and with known substellar objects and present the best matching models as well as the best matching observed objects. Comparing the empirical measurement of the bolometric luminosity to evolutionary models, we find a mass of $12.9\pm0.2$ $\mathcal{M}_\mathrm{Jup}$, an effective temperature of $1724\pm15$ K, a radius of $1.46\pm0.01$ $\mathcal{R}_\mathrm{Jup}$, and a surface gravity of $\log g = 4.18\pm0.01$ [dex] (cgs). The stated uncertainties are statistical errors only, and do not incorporate any uncertainty on the evolutionary models. Using atmospheric models, we find an effective temperature of $1700-1800$ K and a surface gravity of $\log g = 3.5$-$4.0$ [dex] depending upon model. These values agree well with other publications and with "hot-start" predictions from planetary evolution models. Further, we find that the spectrum of $\beta$ Pic b best matches a low-surface gravity L2$\pm$1 brown dwarf. Finally comparing the spectrum to field brown dwarfs we find the the spectrum best matches 2MASS J04062677-381210 and 2MASS J03552337+1133437.
74 citations
TL;DR: In this paper, the H band spectroscopic and Halpha photometric observations of HD 100546 obtained with GPI and MagAO were used to detect H band emission at the location of the protoplanet HD100546b, but show that choice of data processing parameters strongly affects the morphology of this source.
Abstract: We present H band spectroscopic and Halpha photometric observations of HD 100546 obtained with GPI and MagAO. We detect H band emission at the location of the protoplanet HD 100546b, but show that choice of data processing parameters strongly affects the morphology of this source. It appears point-like in some aggressive reductions, but rejoins an extended disk structure in the majority of the others. Furthermore, we demonstrate that this emission appears stationary on a timescale of 4.6 yrs, inconsistent at the 2sigma level with a Keplerian clockwise orbit at 59 au in the disk plane. The H band spectrum of the emission is inconsistent with any type of low effective temperature object or accreting protoplanetary disk. It strongly suggests a scattered light origin, as it is consistent with the spectrum of the star and the spectra extracted at other locations in the disk. A non detection at the 5sigma level of HD 100546b in differential Halpha imaging places an upper limit, assuming the protoplanet lies in a gap free of extinction, on the accretion luminosity and accretion rate of 1.7E-4 Lsun and MMdot<6.4E-7Mjup^2/yr for 1Rjup. These limits are comparable to the accretion luminosity and rate of TTauri-stars or LkCa 15b. Taken together, these lines of evidence suggest that the H band source at the location of HD 100546b is not emitted by a planetary photosphere or an accreting circumplanetary disk but is a disk feature enhanced by the PSF subtraction process. This non-detection is consistent with the non-detection in the K band reported in an earlier study but does not exclude the possibility that HD 100546b is deeply embedded.
62 citations
TL;DR: In this article, the authors describe a super-Earth-size (2.30 +/- 0.16 R-circle plus) planet transiting an early K-type dwarf star in the Campaign 4 field observed by the K2 mission.
Abstract: We describe a 'super-Earth'-size (2.30 +/- 0.16 R-circle plus)planet transiting an early K-type dwarf star in the Campaign 4 field observed by the K2 mission. The host star, EPIC 210363145, was ide ...
58 citations
University of Victoria1, National Research Council2, University of California, Berkeley3, Stanford University4, Search for extraterrestrial intelligence5, Université de Montréal6, Brown University7, Lawrence Livermore National Laboratory8, University of Arizona9, Subaru10, University of Toronto11, University of Georgia12, University of Grenoble13, University of California, Los Angeles14, Durham University15, Johns Hopkins University16, European Southern Observatory17, University of California, San Diego18, Ames Research Center19, University of Western Ontario20, Stony Brook University21, American Museum of Natural History22, Arizona State University23, Space Telescope Science Institute24, Cornell University25, California Institute of Technology26, The Aerospace Corporation27
TL;DR: In this article, the authors proposed a method to use a two-dimensional model of the Earth's magnetic field to estimate the distance from a single point to a fixed point of interest.
Abstract: National Aeronautics and Space Administration; National Science Foundation; U.S. Department of Energy by Lawrence Livermore National Laboratory [DE-AC52-07NA27344]; NASA grants [NNX11AD21G, NNX15AD95/NEXSS, NX14AJ80G]; NSF grants [AST-0909188, AST-1313718]
24 citations
TL;DR: In this article, the low-mass companion to HD 984 B was observed with the Gemini Planet Imager as a part of the NASA Exoplanet Survey campaign, and the spectral structure at different spatial frequencies with the proper spectral noise correlation was analyzed.
Abstract: We present new observations of the low-mass companion to HD 984 taken with the Gemini Planet Imager as a part of the Gemini Planet Imager Exoplanet Survey campaign. Images of HD 984 B were obtained in the J (1.12--1.3 micron) and H (1.50--1.80 micron) bands. Combined with archival epochs from 2012 and 2014, we fit the first orbit to the companion to find an 18 AU (70 year) orbit with a 68% confidence interval between 14 and 28 AU, an eccentricity of 0.18 with a 68% confidence interval between 0.05 and 0.47, and an inclination of 119 degrees with a 68% confidence interval between 114 degrees and 125 degrees. To address considerable spectral covariance in both spectra, we present a method of splitting the spectra into low and high frequencies to analyze the spectral structure at different spatial frequencies with the proper spectral noise correlation. Using the split spectra, we compare to known spectral types using field brown dwarf and low-mass star spectra and find a best fit match of a field gravity M6.5+/-1.5 spectral type with a corresponding temperature of 2730+120 K. Photometry of the companion yields a luminosity of log(L_bol/L_sun) = -2.88+/-0.07 dex, using DUSTY models. Mass estimates, again from DUSTY models, find an age-dependent mass of 34+/-1 to 95+/-4 M_Jup. These results are consistent with previous measurements of the object.
07 Sep 2017
TL;DR: The Gemini Planet Imager (GPI) as mentioned in this paper is a near-infrared high-contrast imager on the 8m Gemini South telescope, optimized for direct detection and characterization of extrasolar Jovian-mass planets and circumstellar disks.
Abstract: The Gemini Planet Imager (GPI) is a near-infrared high-contrast imager on the 8-m Gemini South telescope, optimized for the direct detection and characterization of extrasolar Jovian-mass planets and circumstellar disks. The instrument includes a dual-channel polarimetry mode designed to detect the inherently polarized light scattered off debris disks and protoplanetary disks and suppress unpolarized light from the host star. GPI has imaged over two dozen circumstellar disks {detecting some for the first time in scattered light {and carried out polarimetric measurements of brown dwarfs and exoplanets. Here, we review the current status of the debris disk component of the GPI Exoplanet Survey and report on updates to standard data reduction techniques that improve upon the achievable polarimetric contrasts.
01 Sep 2017
TL;DR: An automated and flexible data processing framework, which is term the GPIES Data Cruncher, combines multiple data reduction pipelines together to intelligently process all spectroscopic, polarimetric, and calibration data taken with GPIES.
Abstract: The Gemini Planet Imager Exoplanet Survey (GPIES) is a multi-year direct imaging survey of 600 stars to discover and characterize young Jovian exoplanets and their environments. We have developed an automated data architecture to process and index all data related to the survey uniformly. An automated and flexible data processing framework, which we term the GPIES Data Cruncher, combines multiple data reduction pipelines together to intelligently process all spectroscopic, polarimetric, and calibration data taken with GPIES. With no human intervention, fully reduced and calibrated data products are available less than an hour after the data are taken to expedite follow-up on potential objects of interest. The Data Cruncher can run on a supercomputer to reprocess all GPIES data in a single day as improvements are made to our data reduction pipelines. A backend MySQL database indexes all files, which are synced to the cloud, and a front-end web server allows for easy browsing of all files associated with GPIES. To help observers, quicklook displays show reduced data as they are processed in real-time, and chatbots on Slack post observing information as well as reduced data products. Together, the GPIES automated data processing architecture reduces our workload, provides real-time data reduction, optimizes our observing strategy, and maintains a homogeneously reduced dataset to study planet occurrence and instrument performance.
TL;DR: An updated Self-structuring Data Learning Algorithm with multiscale grid processing to improve detection classification in the algorithm shows much better target detection and tracking with the real-world data.
Abstract: Previously, we proposed and implemented a Self-structuring Data Learning Algorithm. This realized software package and the concept are still progressing. Earlier, it was tested with synthetic data and exhibited interesting results. The objectives of this paper are testing the algorithm with raw infrared and visual images and updating the algorithm as required. We first performed registration transformation and detection from the images with an existing software package. We then registered the detections with the registration transformations from both infrared and visual images. The registered detections were delivered to the algorithm for target detection and tracking without modification. Results revealed inability to handle very noisy infrared image features. To overcome this problem, we developed multiscale grid processing to improve detection classification in the algorithm. This updated algorithm shows much better target detection and tracking with the real-world data. More algorithm enhancements are in work such as incorporating pattern recognition, classification, and fusion.