Science yield estimate with the Wide-Field Infrared Survey Telescope coronagraph

Traub, Wesley A.; Breckinridge, James B.; Greene, Thomas P.; Guyon, Olivier; Kasdin, N. Jeremy; Macintosh, Bruce

doi:10.1117/1.jatis.2.1.011020

Cited by 24 publications

(26 citation statements)

References 13 publications

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“…In the next decade, NASA's Wide Field Infrared Survey Telescope (WFIRST), equipped with an optical (0.4-0.95 μm) Coronagraphic Instrument (CGI), will obtain photometry and spectra for extrasolar planets with contrasts as low as 10 −10 and angular separations between 0 1 and 0 5 (Traub et al 2016). The WFIRST CGI prime survey will target a number of planets detected via radial velocity both photometrically (0.4-0.95 μm) and spectroscopically (0.6-0.95 μm).…”

Section: Implications For Jwst and Wfirstmentioning

confidence: 99%

On the Composition of Young, Directly Imaged Giant Planets

Moses

Marley

Zahnle

et al. 2016

ApJ

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The past decade has seen significant progress on the direct detection and characterization of young, self-luminous giant planets at wide orbital separations from their host stars. Some of these planets show evidence for disequilibrium processes like transport-induced quenching in their atmospheres; photochemistry may also be important, despite the large orbital distances. These disequilibrium chemical processes can alter the expected composition, spectral behavior, thermal structure, and cooling history of the planets, and can potentially confuse determinations of bulk elemental ratios, which provide important insights into planet-formation mechanisms. Using a thermo/photochemical kinetics and transport model, we investigate the extent to which disequilibrium chemistry affects the composition and spectra of directly imaged giant exoplanets. Results for specific "young Jupiters" such as HR 8799 b and 51 Eri b are presented, as are general trends as a function of planetary effective temperature, surface gravity, incident ultraviolet flux, and strength of deep atmospheric convection. We find that quenching is very important on young Jupiters, leading to CO/CH 4 and N 2 /NH 3 ratios much greater than, and H 2 O mixing ratios a factor of a few less than, chemical-equilibrium predictions. Photochemistry can also be important on such planets, with CO 2 and HCN being key photochemical products. Carbon dioxide becomes a major constituent when stratospheric temperatures are low and recycling of water via the H 2 + OH reaction becomes kinetically stifled. Young Jupiters with effective temperatures 700 K are in a particularly interesting photochemical regime that differs from both transiting hot Jupiters and our own solar-system giant planets.

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Section: Implications For Jwst and Wfirstmentioning

confidence: 99%

On the Composition of Young, Directly Imaged Giant Planets

Moses

Marley

Zahnle

et al. 2016

ApJ

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“…Much work has gone into estimating the yield of the imaging portion of the mission. Greco & Burrows (2015) performed Monte Carlo simulations to quantify the detectability of giant planets under various conditions in the context of WFIRST, (see also Savransky & Garrett 2016;Traub et al 2016;Garrett et al 2017). Many quantitative predictions of yields in these studies depend upon assumptions of instrument performance and extrapolations of underlying exoplanet populations into regimes for which we do not yet have sufficient data.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Exoplanet Atmospheres with the Optical Coronagraph on WFIRST

Lacy

Shlivko

Burrows

2019

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Wide-Field Infrared Survey Telescope (WFIRST)-CGI is a NASA technology demonstration mission that is charged with demonstrating key technologies for future exo-Earth imaging missions in space. In the process, it will obtain images and low-resolution spectra of a handful to a dozen extrasolar planets and possibly protoplanetary disks. Its unprecedented contrast levels in the optical will provide astronomers' with their first direct look at mature, Jupiter-sized planets at moderate separations. This paper addresses the question: what science can be done with such data? An analytic noise model, which is informed by the ongoing engineering developments, is used to compute maximum achievable signal-to-noise ratios and scientifically viable integration times for hypothetical star-planet systems, as well as to investigate the constraining power of various combinations of WFIRST-CGI photometric and spectral observations. This work introduces two simple models for planetary geometric albedos, which are inspired largely by the solar system's gas giants. The first planet model is a hybrid Jupiter-Neptune model, which separately treats the short and long wavelengths where chromophores and methane dominate absorption, respectively. The second planet model fixes cloud and haze properties in CoolTLusty to match Jupiter's albedo spectrum, it then perturbs only the metallicity. MCMC retrievals performed on simulated observations are used to assess the precision with which planet model parameters can be measured subject to different exposure times and observing cases. Planet radius is recovered within±15% for all observing cases with both the hybrid model and the CoolTLusty metallicity grid. Fit results for both models' parameterizations of geometric albedo spectra demonstrate that a rough indication of the metallicity or methane content should be possible for some WFIRST-CGI targets. We conclude that real observations will likely be able to differentiate between extreme cases using these models, but will lack the precision necessary to uncover subtle trends.

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“…From the current AFTA CGI science yield estimates, 24 it is evident that the brightest 15 of these RV exoplanets can all be detected with a total integration time of 3 days. We anticipate that there are yet unseen exoplanet systems that will be revealed in ongoing RV searches from the ground and in discovery-mode observations with the AFTA coronagraph.…”

Section: Hybrid Lyot Coronagraph Science Performancementioning

confidence: 99%

Hybrid Lyot coronagraph for WFIRST-AFTA: coronagraph design and performance metrics

Trauger

Moody

Krist

et al. 2016

J. Astron. Telesc. Instrum. Syst

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Abstract. The prospect of extreme high-contrast astronomical imaging from space has inspired developments of new coronagraph methods for exoplanet imaging and spectroscopy. However, the requisite imaging contrast, at levels of 1 billion to one or better for the direct imaging of cool mature exoplanets in reflected visible starlight, leads to challenging new requirements on the stability and control of the optical wavefront, at levels currently beyond the reach of ground-based telescopes. We review the design, performance, and science prospects for the hybrid Lyot coronagraph (HLC) on the WFIRST-AFTA telescope. Together with a pair of deformable mirrors for active wavefront control, the HLC creates a full 360-deg high-contrast dark field of view at 10 −9 contrast levels or better, extending to within angular separations of 3 λ 0 ∕D from the central star, over spectral bandwidths of 10% or more.

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Science yield estimate with the Wide-Field Infrared Survey Telescope coronagraph

Cited by 24 publications

References 13 publications

On the Composition of Young, Directly Imaged Giant Planets

On the Composition of Young, Directly Imaged Giant Planets

Characterization of Exoplanet Atmospheres with the Optical Coronagraph on WFIRST

Hybrid Lyot coronagraph for WFIRST-AFTA: coronagraph design and performance metrics

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