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8 results on '"Kellen Lawson"'

1. Direct Imaging and Astrometric Detection of a Gas Giant Planet Orbiting an Accelerating Star

Author

Thayne Currie, G. Mirek Brandt, Timothy D. Brandt, Brianna Lacy, Adam Burrows, Olivier Guyon, Motohide Tamura, Ranger Y. Liu, Sabina Sagynbayeva, Taylor Tobin, Jeffrey Chilcote, Tyler Groff, Christian Marois, William Thompson, Simon J. Murphy, Masayuki Kuzuhara, Kellen Lawson, Julien Lozi, Vincent Deo, Sebastien Vievard, Nour Skaf, Taichi Uyama, Nemanja Jovanovic, Frantz Martinache, N. Jeremy Kasdin, Tomoyuki Kudo, Michael McElwain, Markus Janson, John Wisniewski, Klaus Hodapp, Jun Nishikawa, Krzysztof Hełminiak, Jungmi Kwon, and Masahiko Hayashi

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Multidisciplinary, Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics
Abstract

Direct imaging of gas giant exoplanets provides key information on planetary atmospheres and the architectures of planetary systems. However, few planets have been detected in blind surveys used to achieve imaging detections. Using Gaia and Hipparcos astrometry we identified dynamical evidence for a gas giant planet around the nearby star HIP 99770 and then confirmed this planet by direct imaging with the Subaru Coronagraphic Extreme Adaptive Optics Project. HIP 99770 b orbits 17 astronomical units from its host star, with an insolation comparable to Jupiter's and a dynamical mass of 13.9--16.1 Jupiter masses. Its planet-to-star mass ratio (7--8$\times$10$^{-3}$) is comparable to that other directly-imaged planets. The planet's atmosphere resembles an older, less-cloudy analogue of the atmospheres of previously-imaged exoplanets around HR 8799., Authors' version of revised paper, published in Science on April 14, 2023 (passed independent peer review/was recommended for publication in Science by external referees on July 5, 2022). First joint direct imaging + astrometric discovery of an exoplanet. 49 pages, 18 figures, 6 tables

Published
2022

2. Images of Embedded Jovian Planet Formation At A Wide Separation Around AB Aurigae

Author

Thayne Currie, Kellen Lawson, Glenn Schneider, Wladimir Lyra, John Wisniewski, Carol Grady, Olivier Guyon, Motohide Tamura, Takayuki Kotani, Hajime Kawahara, Timothy Brandt, Taichi Uyama, Takayuki Muto, Ruobing Dong, Tomoyuki Kudo, Jun Hashimoto, Misato Fukagawa, Kevin Wagner, Julien Lozi, Jeffrey Chilcote, Taylor Tobin, Tyler Groff, Kimberly Ward-Duong, William Januszewski, Barnaby Norris, Peter Tuthill, Nienke van der Marel, Michael Sitko, Vincent Deo, Sebastien Vievard, Nemanja Jovanovic, Frantz Martinache, and Nour Skaf

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

Direct images of protoplanets embedded in disks around infant stars provide the key to understanding the formation of gas giant planets like Jupiter. Using the Subaru Telescope and Hubble Space Telescope, we find evidence for a jovian protoplanet around AB Aurigae orbiting at a wide projected separation (93 au), likely responsible for multiple planet-induced features in the disk. Its emission is reproducible as reprocessed radiation from an embedded protoplanet. We also identify two structures located at 430-580 au that are candidate sites of planet formation. These data reveal planet formation in the embedded phase and a protoplanet discovery at wide, > 50 au separations characteristic of most imaged exoplanets. With at least one clump-like protoplanet and multiple spiral arms, the AB Aur system may also provide the evidence for a long-considered alternative to the canonical model for Jupiter's formation: disk (gravitational) instability., Author's personal version: 19 pages, 5 Figures, 1 Table; 32 Supplementary pages, 18 Supplementary Figures, 1 Supplementary Table; Accepted for Publication in Nature Astronomy. Published version: https://www.nature.com/articles/s41550-022-01634-x

Published
2022

3. Direct Imaging Discovery and Dynamical Mass of a Substellar Companion Orbiting an Accelerating Hyades Sun-like Star with SCExAO/CHARIS

Author

Masayuki Kuzuhara, Thayne Currie, Takuya Takarada, Timothy D. Brandt, Bun’ei Sato, Taichi Uyama, Markus Janson, Jeffrey Chilcote, Taylor Tobin, Kellen Lawson, Yasunori Hori, Olivier Guyon, Tyler D. Groff, Julien Lozi, Sebastien Vievard, Ananya Sahoo, Vincent Deo, Nemanja Jovanovic, Kyohoon Ahn, Frantz Martinache, Nour Skaf, Eiji Akiyama, Barnaby R. Norris, Mickaël Bonnefoy, Krzysztof G. Hełminiak, Tomoyuki Kudo, Michael W. McElwain, Matthias Samland, Kevin Wagner, John Wisniewski, Gillian R. Knapp, Jungmi Kwon, Jun Nishikawa, Eugene Serabyn, Masahiko Hayashi, and Motohide Tamura

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics
Abstract

We present the direct-imaging discovery of a substellar companion in orbit around a Sun-like star member of the Hyades open cluster. So far, no other substellar companions have been unambiguously confirmed via direct imaging around main-sequence stars in Hyades. The star HIP 21152 is an accelerating star as identified by the astrometry from the Gaia and Hipparcos satellites. We have detected the companion, HIP 21152 B, in multi-epoch using the high-contrast imaging from SCExAO/CHARIS and Keck/NIRC2. We have also obtained the stellar radial-velocity data from the Okayama 188cm telescope. The CHARIS spectroscopy reveals that HIP 21152 B's spectrum is consistent with the L/T transition, best fit by an early T dwarf. Our orbit modeling determines the semi-major axis and the dynamical mass of HIP 21152 B to be 17.5$^{+7.2}_{-3.8}$ au and 27.8$^{+8.4}_{-5.4}$ $M_{\rm{Jup}}$, respectively. The mass ratio of HIP 21152 B relative to its host is $\approx$2\%, near the planet/brown dwarf boundary suggested from recent surveys. Mass estimates inferred from luminosity evolution models are slightly higher (33--42 $M_{\rm{Jup}}$). With a dynamical mass and a well-constrained age due to the system's Hyades membership, HIP 21152 B will become a critical benchmark in understanding the formation, evolution, and atmosphere of a substellar object as a function of mass and age. Our discovery is yet another key proof-of-concept for using precision astrometry to select direct imaging targets., Comment: 21 pages (11 pages in main body), 8 figures (4 figures in main body). Accepted for Publication in ApJL at July 9, 2022 (UT)

Published
2022
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4. The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b

Author

Brittany E. Miles, Beth A. Biller, Polychronis Patapis, Kadin Worthen, Emily Rickman, Kielan K. W. Hoch, Andrew Skemer, Marshall D. Perrin, Niall Whiteford, Christine H. Chen, B. Sargent, Sagnick Mukherjee, Caroline V. Morley, Sarah E. Moran, Mickael Bonnefoy, Simon Petrus, Aarynn L. Carter, Elodie Choquet, Sasha Hinkley, Kimberly Ward-Duong, Jarron M. Leisenring, Maxwell A. Millar-Blanchaer, Laurent Pueyo, Shrishmoy Ray, Steph Sallum, Karl R. Stapelfeldt, Jordan M. Stone, Jason J. Wang, Olivier Absil, William O. Balmer, Anthony Boccaletti, Mariangela Bonavita, Mark Booth, Brendan P. Bowler, Gael Chauvin, Valentin Christiaens, Thayne Currie, Camilla Danielski, Jonathan J. Fortney, Julien H. Girard, Carol A. Grady, Alexandra Z. Greenbaum, Thomas Henning, Dean C. Hines, Markus Janson, Paul Kalas, Jens Kammerer, Grant M. Kennedy, Matthew A. Kenworthy, Pierre Kervella, Pierre-Olivier Lagage, Ben W. P. Lew, Michael C. Liu, Bruce Macintosh, Sebastian Marino, Mark S. Marley, Christian Marois, Elisabeth C. Matthews, Brenda C. Matthews, Dimitri Mawet, Michael W. McElwain, Stanimir Metchev, Michael R. Meyer, Paul Molliere, Eric Pantin, Andreas Quirrenbach, Isabel Rebollido, Bin B. Ren, Glenn Schneider, Malavika Vasist, Mark C. Wyatt, Yifan Zhou, Zackery W. Briesemeister, Marta L Bryan, Per Calissendorff, Faustine Cantalloube, Gabriele Cugno, Matthew De Furio, Trent J. Dupuy, Samuel M. Factor, Jacqueline K. Faherty, Michael P. Fitzgerald, Kyle Franson, Eileen C. Gonzales, Callie E. Hood, Alex R. Howe, Adam L. Kraus, Masayuki Kuzuhara, Anne-Marie Lagrange, Kellen Lawson, Cecilia Lazzoni, Pengyu Liu, Jorge Llop-Sayson, James P. Lloyd, Raquel A. Martinez, Johan Mazoyer, Sascha P. Quanz, Jea Adams Redai, Matthias Samland, Joshua E. Schlieder, Motohide Tamura, Xianyu Tan, Taichi Uyama, Arthur Vigan, Johanna M. Vos, Kevin Wagner, Schuyler G. Wolff, Marie Ygouf, Xi Zhang, Keming Zhang, Zhoujian Zhang, University of California [Santa Cruz] (UC Santa Cruz), University of California (UC), University of Edinburgh, Departement Erdwissenschaften [ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Johns Hopkins University (JHU), Space Telescope Science Institute (STSci), University of California [San Diego] (UC San Diego), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université de Liège, Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), astro-ph.SR, Astrophysics - Solar and Stellar Astrophysics, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Space and Planetary Science, astro-ph.EP, FOS: Physical sciences, Astronomy and Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics
Abstract

We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is a $, Comment: Accepted ApJL Iterations of spectra reduced by the ERS team are hosted at this link: https://github.com/bemiles/JWST_VHS1256b_Reduction/tree/main/reduced_spectra

Published
2022
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5. Multiband Imaging of the HD 36546 Debris Disk: A Refined View from SCExAO/CHARIS*

Author

Kellen Lawson, Thayne Currie, John P. Wisniewski, Motohide Tamura, Jean-Charles Augereau, Timothy D. Brandt, Olivier Guyon, N. Jeremy Kasdin, Tyler D. Groff, Julien Lozi, Vincent Deo, Sebastien Vievard, Jeffrey Chilcote, Nemanja Jovanovic, Frantz Martinache, Nour Skaf, Thomas Henning, Gillian Knapp, Jungmi Kwon, Michael W. McElwain, Tae-Soo Pyo, Michael L. Sitko, Taichi Uyama, Kevin Wagner, Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France, National Astronomical Observatory of Japan (NAOJ), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), University of California [Santa Barbara] (UCSB), University of California, Princeton University, NASA Goddard Space Flight Center (GSFC), National Astronomical Observatory of Japan, Subaru Telescope, 650 North A‘ohoku Place, Hilo, HI 96720, United States, University of Notre Dame [Indiana] (UND), California Institute of Technology (CALTECH), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, ISAS/JAXA, and NASA

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), 010309 optics, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, FOS: Physical sciences, Astronomy and Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 01 natural sciences, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics
Abstract

We present the first multi-wavelength (near-infrared; $1.1 - 2.4$ $\mu m$) imaging of HD 36546's debris disk, using the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system coupled with the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS). As a 3-10 Myr old star, HD 36546 presents a rare opportunity to study a debris disk at very early stages. SCExAO/CHARIS imagery resolves the disk over angular separations of $\rho \sim 0.25" - 1.0"$ (projected separations of $\rm{r_{proj}} \sim 25 - 101$ $\rm{au}$) and enables the first spectrophotometric analysis of the disk. The disk's brightness appears symmetric between its eastern and western extents and it exhibits slightly blue near-infrared colors on average (e.g. $J-K =-0.4\pm0.1$) $-$ suggesting copious sub-micron sized or highly porous grains. Through detailed modeling adopting a Hong scattering phase function (SPF), instead of the more common Henyey-Greenstein function, and using the differential evolution optimization algorithm, we provide an updated schematic of HD 36546's disk. The disk has a shallow radial dust density profile ($\alpha_{in} \approx 1.0$ and $\alpha_{out} \approx -1.5$), a fiducial radius of $r_0 \approx 82.7$ au, an inclination of $i \approx 79.1^\circ$, and a position angle of $\rm PA \approx 80.1^\circ$. Through spine tracing, we find a spine that is consistent with our modeling, but also with a "swept-back wing" geometry. Finally, we provide constraints on companions, including limiting a companion responsible for a marginal Hipparcos-Gaia acceleration to a projected separation of $\lesssim 0.2''$ and to a minimum mass of $\lesssim 11$ $\rm M_{Jup}$., Comment: 23 pages, 19 figures; corrected an error in the abstract, added a reference in Section 2

Published
2021
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6. A Spatially-resolved Large Cavity of the J0337 Protoplanetary Disk in Perseus

Author

Taichi Uyama, Garreth Ruane, Kellen Lawson, Takayuki Muto, Charles Beichman, and Nienke van der Marel

Subjects
Protoplanetary disks, Planet formation, Earth and Planetary Astrophysics (astro-ph.EP), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics
Abstract

We present Keck/NIRC2 $K_{\rm p}L_{\rm p}$ high-contrast imaging observations of a J0337 protoplanetary disk. The data discover the spatially-resolved large cavity, which is the second report among protoplanetary disks in the Perseus star forming region after the LkH$\alpha$~330 system. Our data and forward modeling using RADMC-3D suggests $\sim80$~au for the cavity radius. There is discrepancy between J0337's SED and the modeled SED at $\sim10\micron$ and this suggests an unseen inner disk. We also searched for companions around J0337 but did not detect any companion candidates at separations between $0\farcs1$ and $2\farcs5$. The $L_{\rm p}$-band detection limit corresponds to $\sim20 M_{\rm Jup}$ at 60~au, $\sim9-10 M_{\rm Jup}$ at 90~au, and $\sim3 M_{\rm Jup}$ at $>120$~au. Compared with other young systems with large cavities such as PDS~70 and RX~J1604, multiple Jovian planets, a single eccentric Jovian planet, or a massive brown-dwarf at an inner separation could exist within the cavity., Comment: 10 pages, 11 figures, accepted for publication in AJ

Published
2022
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7. SCExAO/CHARIS Direct Imaging Discovery of a 20 au Separation, Low-mass Ratio Brown Dwarf Companion to an Accelerating Sun-like Star *

Author

Trent J. Dupuy, John P. Wisniewski, Carol A. Grady, Vincent Deo, Gillian R. Knapp, Michael W. McElwain, Jungmi Kwon, Matthew Wahl, Daniel Michalik, Kevin Wagner, Masayuki Kuzuhara, Yunlin Zeng, Markus Janson, Sébastien Vievard, Kellen Lawson, Nemanja Jovanovic, Olivier Guyon, Yiting Li, Julien Lozi, Michael Letawsky, Taichi Uyama, Tyler D. Groff, Timothy D. Brandt, Ananya Sahoo, Jeffery Chilcote, Frantz Martinache, Thayne Currie, G. Mirek Brandt, Motohide Tamura, Christian Marois, Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France, National Astronomical Observatory of Japan (NAOJ), Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, University of Victoria [Canada] (UVIC), NASA, National Astronomical Observatory of Japan, Subaru Telescope, 650 North A‘ohoku Place, Hilo, HI 96720, United States, California Institute of Technology (CALTECH), Institute for Astronomy [Edinburgh] (IfA), University of Edinburgh, Institut de Mathématiques de Marseille (I2M), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Brown dwarf, FOS: Physical sciences, Astrophysics, 01 natural sciences, 7. Clean energy, Spectral line, Photometry (optics), Observatory, 0103 physical sciences, direct imaging (387), 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), astronomical instrumentation (799), Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Physics, Earth and Planetary Astrophysics (astro-ph.EP), astronomical techniques (1684), Astronomy and Astrophysics, brown dwarfs (185), Astrometry, Mass ratio, exoplanet detection methods (489), Exoplanet, coronagraphic imaging (313), astronomical optics (88), Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, exoplanets (498), Low Mass, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract

We present the direct imaging discovery of a substellar companion to the nearby Sun-like star, HD 33632 Aa, at a projected separation of $\sim$ 20 au, obtained with SCExAO/CHARIS integral field spectroscopy complemented by Keck/NIRC2 thermal infrared imaging. The companion, HD 33632 Ab, induces a 10.5$\sigma$ astrometric acceleration on the star as detected with the $Gaia$ and $Hipparcos$ satellites. SCExAO/CHARIS $JHK$ (1.1--2.4 $\mu$m) spectra and Keck/NIRC2 $L_{\rm p}$ (3.78 $\mu$m) photometry are best matched by a field L/T transition object: an older, higher gravity, and less dusty counterpart to HR 8799 cde. Combining our astrometry with $Gaia/Hipparcos$ data and archival Lick Observatory radial-velocities, we measure a dynamical mass of 46.4 $\pm$ 8 $M_{\rm J}$ and an eccentricity of $e$ $, Comment: 11 pages, 3 figures, 2 tables; ApJ Letters in press. First discovery from SCExAO/CHARIS; first substellar companion discovered through direct imaging using Gaia for target selection

Published
2020
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8. Identification of Stellar Flares Using Differential Evolution Template Optimization

Author

Kellen Lawson, Eric C. Bellm, John P. Wisniewski, David L. Shupe, and Adam F. Kowalski

Subjects
010504 meteorology & atmospheric sciences, Population, FOS: Physical sciences, Astrophysics, Stellar classification, 01 natural sciences, law.invention, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Time domain, education, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, education.field_of_study, Astronomy and Astrophysics, Light curve, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Differential evolution, Variable star, Astrophysics - Instrumentation and Methods for Astrophysics, Flare
Abstract

We explore methods for the identification of stellar flare events in irregularly sampled data of ground-based time domain surveys. In particular, we describe a new technique for identifying flaring stars, which we have implemented in a publicly available Python module called "PyVAN". The approach uses the Differential Evolution algorithm to optimize parameters of empirically derived light-curve templates for different types of stars to fit a candidate light-curve. The difference of the likelihoods that these best-fit templates produced the observed data is then used to delineate targets that are well explained by a flare template but simultaneously poorly explained by templates of common contaminants. By testing on light-curves of known identity and morphology, we show that our technique is capable of recovering flaring status in $69\%$ of all light-curves containing a flare event above thresholds drawn to include $\lt1\%$ of any contaminant population. By applying to Palomar Transient Factory data, we show consistency with prior samples of flaring stars, and identify a small selection of candidate flaring G-type stars for possible follow-up., 15 figures, 24 pages

Published
2019
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