Ground- and Space-based Detection of the Thermal Emission Spectrum of the Transiting Hot Jupiter KELT-2Ab

Piskorz, Danielle; Buzard, Cam; Line, Michael R.; Knutson, Heather A.; Benneke, Björn; Crockett, N. R.; Lockwood, Alexandra; Blake, Geoffrey A.; Barman, Travis; Bender, Chad F.; Deming, Drake; Johnson, John Asher

doi:10.3847/1538-3881/aad781

Cited by 57 publications

(77 citation statements)

References 56 publications

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“…it is a two-dimensional cross correlation with the stellar coefficients dominating the planet coefficients by orders of magnitude. The mapping of Lockwood et al (2014) was also recently adopted in Piskorz et al (2018) to combine Keck NIRSPEC K-band data with Spitzer for the transiting hot-Jupiter Kelt-2 Ab. However, we again stress that such formalism cannot be applied to our data analysis where we make use of the change in planet radial velocity with time.…”

Section: Mappingsmentioning

confidence: 99%

Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-resolution Cross-correlation Spectroscopy

Brogi

Line

2019

Self Cite

272

392

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High-resolution spectroscopy (R ≥ 25, 000) has recently emerged as one of the leading methods for detecting atomic and molecular species in the atmospheres of exoplanets. However, it has so far been lacking a robust method to extract quantitative constraints on the temperature structure and molecular/atomic abundances. In this work, we present a novel Bayesian atmospheric retrieval framework applicable to high-resolution cross-correlation spectroscopy (HRCCS) that relies on the cross-correlation between data and models for extracting the planetary spectral signal. We successfully test the framework on simulated data and show that it can correctly determine Bayesian credibility intervals on atmospheric temperatures and abundances, allowing for a quantitative exploration of the inherent degeneracies. Furthermore, our new framework permits us to trivially combine and explore the synergies between HRCCS and low-resolution spectroscopy (LRS) to maximally leverage the information contained within each. This framework also allows us to quantitatively assess the impact of molecular line opacities at high resolution. We apply the framework to VLT CRIRES K-band spectra of HD 209458 b and HD 189733 b and retrieve abundant carbon monoxide but subsolar abundances for water, which are largely invariant under different model assumptions. This confirms previous analysis of these datasets, but is possibly at odds with detections of H 2 O at different wavelengths and spectral resolutions. The framework presented here is the first step toward a true synergy between space observatories and ground-based high-resolution observations.

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Section: Mappingsmentioning

confidence: 99%

Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-resolution Cross-correlation Spectroscopy

Brogi

Line

2019

Self Cite

272

392

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“…The median TP profile is shown in black, with 1σ and 2σ confidence intervals outlined in red. Overlaid on top of the retrieval results are radiative-convective equilibrium profiles (blue) derived using the ScCHIMERA modeling tool described in Piskorz et al (2018) and Bonnefoy et al (2018), generated using the T eff and log(g) range derived from the retrieval results. We compute the effective temperature as in Parts I and II by numerically integrating for the bolometric flux of the retrieved spectral spread for each object from 1 -20 µm.…”

Section: Vertical Temperature Structurementioning

confidence: 99%

“…Figure 5 summarizes these trends (red, yellow points) in comparison to predictions from a self-consistent grid model (black curves) and to those derived for the warmer T-dwarfs from Part II (blue points). Our chosen grid model was introduced and validated in Piskorz et al (2018) and Bonnefoy et al (2018). We produce a grid of models given T eff , log(g), metallicity, and assume radiative-convective thermochemical equilibrium.…”

Section: Chemical Trendsmentioning

confidence: 99%

A Uniform Retrieval Analysis of Ultra-cool Dwarfs. III. Properties of Y Dwarfs

Zalesky

Line

Schneider

et al. 2019

ApJ

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109

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Ultra-cool brown dwarfs offer a unique window into understanding substellar atmospheric physics and chemistry. Their strong molecular absorption bands at infrared wavelengths, Jupiter-like radii, cool temperatures, and lack of complicating stellar irradiation, make them ideal test-beds for understanding Jovian-like atmospheres. Here we report the findings of a uniform atmospheric retrieval analysis on a set of 14 Y and T-dwarfs observed with the Hubble Space Telescope Wide Field Camera 3 instrument. From our retrieval analysis, we find the temperature-structures to be largely consistent with radiative-convective equilibrium in most objects. We also determine the abundances of water, methane, and ammonia and upper limits on the alkali metals sodium and potassium. The constraints on water and methane are consistent with predictions from chemical equilibrium models, while those of ammonia may be affected by vertical disequilibrium mixing, consistent with previous works. Our key result stems from the constraints on the alkali metal abundances where we find their continued depletion with decreasing effective temperature, consistent with the trend identified in a previous retrieval analysis on a sample of slightly warmer late T-dwarfs in Line et al. (2017). These constraints show that the previously observed Y-J color trend across the T/Y transition is most likely due to the depletion of these metals in accordance with predictions from equilibrium condensate rainout chemistry. Finally, we simulate future James Webb Space Telescope observations of ultra-cool dwarfs and find that the NIRSpec PRISM offers the best chance at developing high-precision constraints on fundamental atmospheric characteristics.

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“…Previous multi-epoch detection works (e.g., Piskorz et al 2018) have reported significance by comparing the likelihood of a Gaussian fit (representing a detection) versus a linear fit (representing a non-detection) to the peak. This method has given significances of hot Jupiter detections in the range of 3-4σ.…”

Section: Planet Mass and Orbital Solutionmentioning

confidence: 99%

“…These direct detection techniques work by treating a star/planet system as a spectroscopic binary and measuring the radial velocity signature of the planet. This signature will have an opposite phase to the stellar radial velocity curve (see Figure 1), and by combining its amplitude, which we call K p , the planetary Keplerian line-of-sight velocity, with the stellar radial velocity amplitude K, we can break the mass/inclination degeneracy left by the stellar radial velocity technique and further characterize the planet's atmosphere (e.g., Brogi et al 2012Brogi et al , 2013Brogi et al , 2014Lockwood et al 2014;Piskorz et al 2016Piskorz et al , 2017Birkby et al 2017;Piskorz et al 2018). These techniques have been used to detect the presence of H 2 O (e.g., Birkby et al 2017), CO (e.g., Brogi et al 2012), TiO (Nugroho et al 2017), HCN (e.g., Hawker et al 2018), and CH 4 (Guilluy et al 2019) in planetary atmospheres, as well as winds (Snellen et al 2010) and planetary rotation rate (Brogi et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Simulating the Multi-epoch Direct Detection Technique to Isolate the Thermal Emission of the Non-transiting Hot Jupiter HD187123b

Buzard

Finnerty

Piskorz

et al. 2020

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We report the 6.5σ detection of water from the hot Jupiter HD187123b with a Keplerian orbital velocity K p of 53±13 km s −1. This high-confidence detection is made using a multi-epoch, high-resolution, crosscorrelation technique, and corresponds to a planetary mass of-+ 1.4 0.3 0.5 M J and an orbital inclination of 21°±5°. The technique works by treating the planet/star system as a spectroscopic binary and obtaining high signal-tonoise, high-resolution observations at multiple points across the planet's orbit to constrain the system's binary dynamical motion. All together, seven epochs of Keck/NIRSPEC L-band observations were obtained, with five before the instrument upgrade and two after. Using high-resolution SCARLET planetary and PHOENIX stellar spectral models, we were able to drastically increase the confidence of the detection by running simulations that could reproduce, and thus remove, the nonrandom structured noise in the final likelihood space well. The ability to predict multi-epoch results will be extremely useful for furthering the technique. Here, we use these simulations to compare three different approaches to combining the cross correlations of high-resolution spectra and find that the Zucker log(L) approach is least affected by unwanted planet/star correlation for our HD187123 data set. Furthermore, we find that the same total signal-to-noise ratio (S/N) spread across an orbit in many, lower S/N epochs rather than fewer, higher S/N epochs could provide a more efficient detection. This work provides a necessary validation of multi-epoch simulations, which can be used to guide future observations and will be key to studying the atmospheres of farther separated, non-transiting exoplanets.

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Ground- and Space-based Detection of the Thermal Emission Spectrum of the Transiting Hot Jupiter KELT-2Ab

Cited by 57 publications

References 56 publications

Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-resolution Cross-correlation Spectroscopy

Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-resolution Cross-correlation Spectroscopy

A Uniform Retrieval Analysis of Ultra-cool Dwarfs. III. Properties of Y Dwarfs

Simulating the Multi-epoch Direct Detection Technique to Isolate the Thermal Emission of the Non-transiting Hot Jupiter HD187123b

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