Imaging Young Giant Planets From Ground and Space

Beichman, Charles; Krist, John; Trauger, John T.; Greene, T. P.; Oppenheimer, Ben R.; Sivaramakrishnan, Anand; Doyon, René; Boccaletti, A.; Barman, Travis; Rieke, M. J.

doi:10.1086/651057

Cited by 123 publications

(104 citation statements)

References 67 publications

(132 reference statements)

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“…The JWST will have the capability of obtaining high-contrast ( -10 7 ) images of young giant planets (Beichman et al 2010;Clampin 2011), with well-separated ones (3″-10″) being amenable to spectroscopic characterization. The Near Infrared Camera (NIRCam), Mid-Infrared Instrument (MIRI), and NearInfraRed Imager and Slitless Spectrograph (NIRISS) all have imaging modes, with MIRI and NIRCam having coronagraph options (e.g., Krist et al 2007;Boccaletti et al 2015;Debes et al 2015) and NIRISS having an Aperture Masking Interferometry (AMI) mode (Artigau et al 2014).…”

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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“…However, the predicted PSF subtraction residuals within 1 of the star will remain too high to reach the required contrast (∼10 −5 ) to detect such a cool planet in the mid-infrared. The expected 3-5 µm planet-to-star contrast ratios of the planets (∼2·10 −6 ) are also too extreme for the NIRCam coronagraph detection limits inside 0.5 (Beichman et al 2010) and for NIRISS aperture masking interferometry (Artigau et al 2014). …”

Section: Thermal Imaging Of Planets 'B' and 'C'mentioning

confidence: 99%

The mass of planet GJ 676A b from ground-based astrometry

Sahlmann

Lazorenko

Ségransan

et al. 2016

A&A

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GJ 676A is an M0 dwarf hosting both gas-giant and super-Earth-type planets discovered with radial-velocity measurements. Using FORS2/VLT, we obtained position measurements of the star in the plane of the sky that tightly constrain its astrometric reflex motion caused by the super-Jupiter planet 'b' in a 1052-day orbit. This allows us to determine the mass of this planet to M b = 6.7 +1.8 −1.5 M J , which is ∼40 % higher than the minimum mass inferred from the radial-velocity orbit. Using new HARPS radial-velocity measurements, we improve upon the orbital parameters of the inner low-mass planets 'd' and 'e' and we determine the orbital period of the outer giant planet 'c' to P c = 7340 days under the assumption of a circular orbit. The preliminary minimum mass of planet 'c' is M c sin i = 6.8 M J with an upper limit of ∼39 M J that we set using NACO/VLT high-contrast imaging. We also determine precise parallaxes and relative proper motions for both GJ 676A and its wide M3 companion GJ 676B. Despite the probably mature age of the system, the masses and projected separations (∼0 . 1 -0 . 4) of planets 'b' and 'c' make them promising targets for direct imaging with future instruments in space and on extremely large telescopes. In particular, we estimate that GJ 676A b and GJ 676A c are promising targets for directly detecting their reflected light with the WFIRST space mission. Our study demonstrates the synergy of radial-velocity and astrometric surveys that is necessary to identify the best targets for such a mission.

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“…NIRSpec's IFS and MIRI's spectrometer will be used to obtain complete spectra of more widely separated planets. Beichman et al 2010). The on-orbit performance of the coronagraphs will depend sensitively on the drift in telescope wavefront error (WFE) over the duration of a combined target and reference star sequence as well as on the ability of the telescope to hold the star carefully centered on the coronagraphic masks.…”

Section: Planet Characterizationmentioning

confidence: 99%

Observing Exoplanets with the James Webb Space Telescope

Beichman

Greene

2017

Handbook of Exoplanets

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The census of exoplanets has revealed an enormous variety of planets orbiting stars of all ages and spectral types: planets in orbits of less than a day to frigid worlds in orbits over 100 AU; planets with masses 10 times that of Jupiter to planets with masses less than that of Earth; searingly hot planets to temperate planets in the Habitable Zone. The challenge of the coming decade is to move from demography to physical characterization. The James Webb Space Telescope (JWST) is poised to open a revolutionary new phase in our understanding of exoplanets with transit spectroscopy of relatively short period planets and coronagraphic imaging of ones with wide separations from their host stars. This article discusses the wide variety of exoplanet opportunities enabled by JWST's sensitivity and stability, its high angular resolution, and its suite of powerful instruments. These capabilities will advance our understanding of planet formation, brown dwarfs, and the atmospheres of young to mature planets.

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Imaging Young Giant Planets From Ground and Space

Cited by 123 publications

References 67 publications

On the Composition of Young, Directly Imaged Giant Planets

On the Composition of Young, Directly Imaged Giant Planets

The mass of planet GJ 676A b from ground-based astrometry

Observing Exoplanets with the James Webb Space Telescope

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