PandExo: A Community Tool for Transiting Exoplanet Science with<i>JWST</i>&amp;<i>HST</i>

Batalha, Natasha E.; Mandell, Avi M.; Pontoppidan, K. M.; Stevenson, Kevin B.; Lewis, N.; Kalirai, Jason; Earl, N.; Greene, Thomas P.; Li, Albert; Nielsen, L. D.

doi:10.1088/1538-3873/aa65b0

Cited by 323 publications

(256 citation statements)

References 25 publications

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“…We chose the MIRI band because of the broadness of the 6µm water feature and because, as we are not including any systematic noise floor and observing an M3 star, the noise calculations are similar if the nir-IR simulations are binned to R = 100. These calculations were performed using JWST's publicly available noise simulator, PandExo (Batalha et al 2017) for the same planet system shown in Fig.11. Assuming an observability window comparable to TRAPPIST-1 and an inner edge planet, the planet system would need to be observed through the entirety of Cycle 1 (24 transits) to reach the approximate strength of the water feature.…”

Section: Transit Transmission Spectral Featuresmentioning

confidence: 99%

Habitable Moist Atmospheres on Terrestrial Planets near the Inner Edge of the Habitable Zone around M Dwarfs

Kopparapu

Wolf

Arney

et al. 2017

ApJ

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188

269

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Terrestrial planets in the habitable zones (HZs) of low-mass stars and cool dwarfs have received significant scrutiny recently Transit spectroscopy of such planets with JWST represents our best shot at obtaining the spectrum of a habitable planet within the next decade. As these planets are likely tidal-locked, improved 3D numerical simulations of such planetary atmospheres are needed to guide target selection. Here we use a 3-D climate system model, updated with new water-vapor absorption coefficients derived from the HITRAN 2012 database, to study ocean covered planets at the inner edge of the HZ around late-M to mid-K stars (2600K ≤ T ef f ≤ 4500K). Our results indicate that these updated water-vapor coefficients result in significant warming compared to previous studies, so the inner HZ around M-dwarfs is not as close as suggested by earlier work. Assuming synchronously rotating Earth-sized and Earth-massed planets with background 1 bar N 2 atmospheres, we find that planets at the inner -2 -HZ of stars with T ef f > 3000K undergo the classical "moist-greenhouse" (H 2 O mixing ratio > 10 −3 in the stratosphere) at significantly lower surface temperature (∼ 280K) in our 3-D model compared with 1-D climate models (∼ 340K). This implies that some planets around low mass stars can simultaneously undergo water-loss and remain habitable. However, for star with T ef f ≤ 3000K, planets at the inner HZ may directly transition to a runaway state, while bypassing the moist greenhouse water-loss entirely. We analyze transmission spectra of planets in a moist greenhouse regime, and find that there are several prominent H 2 O features, including a broad feature between 5-8 microns, within JWST MIRI instrument range. Thus, relying only upon standard Earth-analog spectra with 24-hour rotation period around M-dwarfs for habitability studies will miss the strong H 2 O features that one would expect to see on synchronously rotating planets around M-dwarf stars, with JWST.

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Section: Transit Transmission Spectral Featuresmentioning

confidence: 99%

Habitable Moist Atmospheres on Terrestrial Planets near the Inner Edge of the Habitable Zone around M Dwarfs

Kopparapu

Wolf

Arney

et al. 2017

ApJ

Self Cite

188

269

View full text Add to dashboard Cite

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“…We simulated JWST data using PandExo for three transits observed with the Near Infrared Spectrograph (NIRSpec) G395H grism Bright Object Time Series and Mid-infrared Instrument (MIRI) slitless Low Resolution Spectroscopy with a noise floor of 10 ppm (Batalha et al 2017). We avoided shorter-wavelength instrument modes that may have trouble Figure 10.…”

Section: Future Prospects With Jwst For Gj 436b's Transmission Spectrummentioning

confidence: 99%

An HST/STIS Optical Transmission Spectrum of Warm Neptune GJ 436b

Lothringer

Benneke

Crossfield

et al. 2018

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GJ 436b is a prime target for understanding warm Neptune exoplanet atmospheres and a target for multiple James Webb Space Telescope (JWST) Guaranteed Time Observation programs. Here, we report the first space-based optical transmission spectrum of the planet using two Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) transit observations from 0.53 to 1.03 μm. We find no evidence for alkali absorption features, nor evidence of a scattering slope longward of 0.53 μm. The spectrum is indicative of moderate to high metallicity (∼100-1000× solar), while moderate-metallicity scenarios (∼100×solar) require aerosol opacity. The optical spectrum also rules out some highly scattering haze models. We find an increase in transit depth around 0.8 μm in the transmission spectra of three different sub-Jovian exoplanets (GJ 436b, HAT-P-26b, and GJ 1214b). While most of the data come from STIS, data from three other instruments may indicate this is not an instrumental effect. Only the transit spectrum of GJ 1214b is well fit by a model with stellar plages on the photosphere of the host star. Our photometric monitoring of the host star reveals a stellar rotation rate of 44.1 days and an activity cycle of 7.4 years. Intriguingly, GJ 436 does not become redder as it gets dimmer, which is expected if star spots were dominating the variability. These insights into the nature of the GJ 436 system help refine our expectations for future observations in the era of JWST, whose higher precision and broader wavelength coverage will shed light on the composition and structure of GJ 436b's atmosphere.

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“…2.4. JWST Simulator We use PandExo (Batalha et al 2017) 8 to simulate secondary eclipse observations of planets akin to HD 189733b, WASP-80b, and GJ 436b. We chose to simulate spectra using the Near-InfraRed Imager and Slitless Spectrograph's Single Object Slitless Spectroscopy mode (NIRISS SOSS) from 0.6 to 2.8 µm (R=700), Near InfraRed Spectrograph's Grism 395 Medium Resolution mode (NIRSpec G395M) from 2.9 to 5 µm (R=1000), and the Mid-InfraRed Instrument's Low Resolution Spectrometer (MIRI LRS) from 5 to 14 µm (R=100).…”

Section: Spectra Generatormentioning

confidence: 99%

A Comparison of Simulated JWST Observations Derived from Equilibrium and Non-equilibrium Chemistry Models of Giant Exoplanets

Blumenthal

Mandell

Hébrard

et al. 2018

ApJ

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We aim to see if the difference between equilibrium and disequilibrium chemistry is observable in the atmospheres of transiting planets by the James Webb Space Telescope (JWST). We perform a case study comparing the dayside emission spectra of three planets like HD 189733b, WASP-80b, and GJ436b, in and out of chemical equilibrium at two metallicities each. These three planets were chosen because they span a large range of planetary masses and equilibrium temperatures, from hot and Jupiter-sized to warm and Neptune-sized. We link the one-dimensional disequilibrium chemistry model from Venot et al. (2012) in which thermochemical kinetics, vertical transport, and photochemistry are taken into account, to the one-dimensional, pseudo line-by-line radiative transfer model, Pyrat Bay, developed especially for hot Jupiters, and then simulate JWST spectra using PandExo for comparing the effects of temperature, metallicity, and radius. We find the most significant differences from 4 to 5 µm due to disequilibrium from CO and CO 2 abundances, and also H 2 O for select cases. Our case study shows a certain "sweet spot" of planetary mass, temperature, and metallicity where the difference between equilibrium and disequilibrium is observable. For a planet similar to WASP-80b, JWST's NIRSpec G395M can detect differences due to disequilibrium chemistry with one eclipse event. For a planet similar to GJ 436b, the observability of differences due to disequilibrium chemistry is possible at low metallicity given five eclipse events, but not possible at the higher metallicity.

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PandExo: A Community Tool for Transiting Exoplanet Science withJWST&HST

Cited by 323 publications

References 25 publications

Habitable Moist Atmospheres on Terrestrial Planets near the Inner Edge of the Habitable Zone around M Dwarfs

Habitable Moist Atmospheres on Terrestrial Planets near the Inner Edge of the Habitable Zone around M Dwarfs

An HST/STIS Optical Transmission Spectrum of Warm Neptune GJ 436b

A Comparison of Simulated JWST Observations Derived from Equilibrium and Non-equilibrium Chemistry Models of Giant Exoplanets

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