Mr. Zhexing Li Profile

Zhexing Li

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Publications (4)

Proceedings Article | 23 August 2024 Presentation + Paper

The Nancy Grace Roman Space Telescope coronagraph community participation program

Dmitry Savransky, Vanessa Bailey, Schuyler Wolff, Maxwell Millar-Blanchaer, Jason Wang, Lisa Altinier, Ramya Anche, Pierre Baudoz, Beth Biller, Sarah Blunt, Wolfgang Brandner, Marah Brinjikji, Oscar Carrión-González, Amanda Chavez, Elodie Choquet, David Doelman, Julien Girard, Alexandra Greenbaum, Samantha Hasler, Justin Hom, James Ingalls, Stephen Kane, N. Jeremy Kasdin, Oliver Krause, Masayuki Kuzuhara, Alexis Lau, Zhexing Li, John Livingston, Patrick Lowrance, Kevin Ludwick, Bruce Macintosh, Eric Mamajek, Mark Marley, Johan Mazoyer, Bertrand Mennesson, Toshiyuki Mizuki, Sarah Moran, Naoshi Murakami, Jun Nishikawa, Malachi Noel, Laurent Pueyo, Sergi Hildebrandt Rafels, Jason Rhodes, Tyler Robinson, Robert De Rosa, Matthias Samland, Nicholas Schragal, Jürgen Schreiber, Jennifer Sobeck, Karl Stapelfeldt, Motohide Tamura, Taichi Uyajma, Arthur Vigan, Michele Woodland, Marie Ygouf, Kenta Yoneta, Robert Zellem, Neil Zimmerman

Proceedings Volume 13092, 130921I (2024) https://doi.org/10.1117/12.3020514

KEYWORDS: Coronagraphy, Stars, Observatories, Space telescopes, Wavefronts, Telescopes, Planets, Observational astronomy, Exoplanets

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Proceedings Article | 23 August 2024 Poster + Paper

The Roman coronagraph community participation program: observation planning

Schuyler Wolff, Jason Wang, Karl Stapelfeldt, Vanessa Bailey, Dmitry Savransky, Justin Hom, Beth Biller, Wolfgang Brandner, Ramye Anche, Sarah Blunt, Marah Brinjikji, Julien Girard, Oliver Krause, Zhexing Li, John Livingston, Maxwell Millar-Blanchaer, Malachi Noel, Laurent Pueyo, Robert De Rosa, Matthias Samland, Nicholas Schragal

Proceedings Volume 13092, 1309255 (2024) https://doi.org/10.1117/12.3020205

KEYWORDS: Stars, Coronagraphy, Exoplanets, Databases, Imaging spectroscopy, Observatories

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SPIE Journal Paper | 28 May 2021 Open Access

Community exoplanet imaging data challenge for Roman CGI and starshade rendezvous

Margaret Turnbull, Neil Zimmerman, Julien Girard, Sergi R. Hildebrandt, Zhexing Li, Ell Bogat, Junellie Gonzalez-Quiles, Christopher Stark, Avi Mandell, Tiffany Meshkat, Stephen Kane

JATIS, Vol. 7, Issue 02, 021218, (May 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.2.021218

KEYWORDS: Planets, Exoplanets, Imaging systems, Signal to noise ratio, Stars, Coronagraphy, Telescopes, Data modeling, Point spread functions, Sensors

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Operating in an unprecedented contrast regime (10 − 7 to 10 − 9), the Roman Coronagraph Instrument (CGI) will serve as a pathfinder for key technologies needed for future Earth-finding missions such as HabEx and LUVOIR. The Roman Exoplanet Imaging Data Challenge (Roman EIDC) was a community engagement effort that tasked participants with extracting exoplanets and their orbits for a 47-UMa-like target star given: (1) 15 years of simulated precursor radial velocity (RV) data and (2) six epochs of simulated imaging taken over the course of the Roman mission. Led by the Turnbull CGI Science Investigation Team, the Roman EIDC was preceded by four tutorial “hack-a-thon” events in Baltimore, Pasadena, New York City, and Tokyo. The Roman EIDC officially launched in October 2019 and ran for 8 months, offering a unique opportunity for exoplanet scientists of all experience levels to get acquainted with realistic near-future imaging data. The Roman EIDC simulated images include four epochs with CGI’s Hybrid Lyot Coronagraph (HLC) plus two epochs with a starshade (SS) assumed to arrive as part of a Starshade Rendezvous later in the mission. We focus on our in-house analysis of the outermost planet “d,” for which the SS’s higher throughput and lower noise floor present a factor of ∼4 improvement in the signal-to-noise ratio over the narrow-field HLC. We find that, although the RV detection was marginal for planet d, the precursor RV data enabled the mass and orbit to be constrained with only two epochs of SS imaging. Including the HLC images in the analysis results in improved measurements over RV + SS alone, with the greatest gains resulting from images taken at epochs near maximum elongation. Combining the two epochs of SS imaging with the RV + HLC data resulted in a factor of ∼2 better orbit and mass determinations over RV + HLC alone. In summary, the Roman CGI, combined with precursor RV data and latermission SS imaging, forms a powerful trifecta in detecting exoplanets and determining their masses, albedos, and system configurations. While the Roman CGI will break new scientific and technological ground with direct imaging of giant exoplanets within ∼5 AU of V ˜ 5 and brighter stars, a Roman Starshade Rendezvous mission would additionally enable the detection of planets out to ∼8 AU in those systems.

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Proceedings Article | 15 December 2020 Poster + Presentation + Paper

The Roman exoplanet imaging data challenge: a major community engagement effort

Julien Girard, Ell Bogat, Junellie Gonzalez-Quiles, Sergi Hildebrandt, Stephen Kane, Zhexing Li, Margaret Turnbull, Christopher Stark, Avi Mandell, Tiffany Meshkat, Neil Zimmerman

Proceedings Volume 11443, 1144337 (2020) https://doi.org/10.1117/12.2561736

KEYWORDS: Exoplanets, Coronagraphy, Planets, Imaging systems, Stars, Point spread functions, Astrophysics, Contamination, Light, Wavefronts

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