scholarly journals Characterizing the Atmospheres of Hot Jupiters: From Spectra to Multi-Color Maps

2008 ◽  
Vol 4 (S253) ◽  
pp. 255-261
Author(s):  
Heather A. Knutson
Keyword(s):  
Emission Spectrum ◽  
Inversion Layer ◽  
Emission Spectra ◽  
Phase Curve ◽  
Hot Jupiters ◽  
Thermal Phase ◽  
Additional Support ◽  
Temperature Inversions ◽  
The Relationship ◽  
Hot Jupiter

AbstractWe present new observations of the emission spectrum of the hot Jupiter TrES-4 designed to test the theory that the presence of temperature inversions in the atmospheres of these planets are correlated with the amount of radiation received by the planet. Our observations reveal that TrES-4 has an emission spectrum similar to that of HD 209458b, which requires the presence of an inversion layer high in the atmosphere and water emission bands in order to explain the observed features, providing additional support for that theory. We also present new observations of the thermal phase curve of HD 189733b at 24 μm, which we combine with our previous observations at 8 μm to examine how circulation in this planet's atmosphere varies as a function of depth. We discuss the relationship between the strength of the day-night circulation on both planets and their other observable properties, in particular their emission spectra.

Searching for 3D effects in the optical, high spectral resolution emission spectrum of KELT-9b

2021 ◽  
Author(s):  
Lorenzo Pino ◽  
Matteo Brogi ◽  
Jean-Michel Désert ◽  
Emily Rauscher
Keyword(s):  
Emission Spectrum ◽  
Spectral Resolution ◽  
Planet Formation ◽  
Emission Spectra ◽  
Optical Emission ◽  
High Spectral Resolution ◽  
Optical Emission Spectrum ◽  
Hot Jupiters ◽  
Atmospheric Structure ◽  
3D Effects

<p>Ultra-hot Jupiters (UHJs; T<sub>eq</sub> ≥ 2500 K) are the hottest gaseous giants known. They emerged as ideal laboratories to test theories of atmospheric structure and its link to planet formation. Indeed, because of their high temperatures, (1) they likely host atmospheres in chemical equilibrium and (2) clouds do not form in their day-side. Their continuum, which can be measured with space-facilities, can be mostly attributed to H- opacity, an indicator of metallicity. From the ground, the high spectral resolution emission spectra of UHJs contains thousands of lines of refractory (Fe, Ti, TiO, …) and volatile species (OH, CO, …), whose combined atmospheric abundances could track planet formation history in a unique way. In this talk, we take a deeper look to the optical emission spectrum of KELT-9b covering planetary phases 0.25 - 0.75 (i.e. between secondary eclipse and quadrature), and search for the effect of atmospheric dynamics and three-dimensionality of the planet atmosphere on the resolved line profiles, in the context of a consolidated statistical framework. We discuss the suitability of the traditionally adopted 1D models to interprete phase-resolved observations of ultra-hot Jupiters, and the potential of this kind of observations to probe their 3D atmospheric structure and dynamics. Ultimately, understanding which factors affect the line-shape in UHJs will also lead to more accurate and more precise abundance measurements, opening a new window on exoplanet formation and evolution.</p>

scholarly journals Temperature inversions on hot super-Earths: the case of CN in nitrogen-rich atmospheres

2020 ◽  
Vol 500 (2) ◽  
pp. 2197-2208
Author(s):  
Mantas Zilinskas ◽  
Yamila Miguel ◽  
Yipeng Lyu ◽  
Morris Bax
Keyword(s):  
Emission Spectrum ◽  
Atmospheric Chemistry ◽  
Emission Spectra ◽  
Low Resolution ◽  
Orbital Parameters ◽  
Short Period ◽  
Orbital Periods ◽  
Temperature Inversions ◽  
Absorption Features

ABSTRACT We show that in extremely irradiated atmospheres of hot super-Earths shortwave absorption of CN can cause strong temperature inversions. We base this study on previous observations of 55 Cancri e, which lead us to believe that ultrashort-period super-Earths can sustain volatile atmospheres, rich in nitrogen and/or carbon. We compute our model atmospheres in a radiative-convective equilibrium for a variety of nitrogen-rich cases and orbital parameters. We demonstrate the effects caused by thermal inversions on the chemistry and compute low-resolution synthetic emission spectra for a range of 0.5–28 $\rm{\mu m}$. Our results indicate that due to shortwave absorption of CN, atmospheres with temperatures above 2000 K and C/O ≥ 1.0 are prone to thermal inversions. CN is one of the few molecules that is extremely stable at large temperatures occurring on the dayside of short-period super-Earths. The emission spectrum of such atmospheres will differ substantially from non-inverted cases. In the case of inversions, absorption features become inverted, showing higher than expected flux. We propose that inversions in hot atmospheres should be the expected norm. Hot super-Earths are some of the most extreme natural laboratories for testing predictions of atmospheric chemistry and structure. They are frequently occurring, bright in emission and have short orbital periods. All these factors make them perfect candidates to be observed with JWST and ARIEL missions.

Characterising Two Ultra-Hot Jupiters with the Hubble Space Telescope

2020 ◽  
Author(s):  
Billy Edwards ◽  
Quentin Changeat ◽  
William Pluriel ◽  
Niall Whiteford ◽  
Kai Hou Yip ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Hubble Space Telescope ◽  
Cloud Model ◽  
Thermal Structure ◽  
Emission Spectra ◽  
Pressure Profile ◽  
Wide Field ◽  
Space Telescope ◽  
Thermal Inversion ◽  
Hot Jupiters

<p>The Hubble Space Telescope’s Wide Field Camera 3 (WFC3) has been widely used for transmission and emission spectroscopy of exoplanet atmospheres, identifying the main molecular constituents, detecting the presence of clouds and probing their thermal structure. Hubble observations of the emission spectra of a number of ultra-hot Jupiters have led to somewhat surprising results. Initially, these very hot planets were predicted to have inverted temperature pressure profiles due to strong optical absorption by TiO/VO in the upper atmospheres. However, observations of their emission spectra have been inconclusive on their thermal structure and composition. While some datasets show rich spectral features, others can be fit with simple blackbody models.</p> <p>We will present the analysis of Hubble WFC3 transmission and emission spectra for two ultra-hot Jupiters: WASP-76 b and KELT-7 b. In each case, the data was reduced and fitted using the open-source codes Iraclis and Taurex3. Previous studies of the WFC3 transmission spectra of WASP-76 b found hints of TiO and VO or non-grey clouds. Accounting for a fainter stellar companion to WASP-76, we reanalyse this data and show that removing the effects of this background star changes the slope of the spectrum, resulting in these visible absorbers no longer being detected, removing the need for a non-grey cloud model to adequately fit the data but maintaining the strong water feature previously seen. However, our analysis of the emission spectrum suggests the presence of titanium oxide (TiO) and an atmospheric thermal inversion. Meanwhile, our study of KELT-7 b uncovers a rich transmission spectrum which suggests the presence of water and H-. In contrast, the extracted emission spectrum does not contain strong absorption features and, although it is not consistent with a simple blackbody, it can be explained by a varying temperature-pressure profile, collision induced absorption (CIA) and H-. </p> <p>These finding bring new insights into the nature of this intriguing class of planets but more data is required to fully understand them and thus we will also present the anticipated results of further characterisation.</p>

scholarly journals A transition between the hot and the ultra-hot Jupiter atmospheres

2020 ◽  
Vol 639 ◽  
pp. A36 ◽  
Author(s):  
Claire Baxter ◽  
Jean-Michel Désert ◽  
Vivien Parmentier ◽  
Mike Line ◽  
Jonathan Fortney ◽  
...  
Keyword(s):  
Near Infrared ◽  
Thermal Structure ◽  
Emission Spectra ◽  
Equilibrium Temperature ◽  
Hot Jupiters ◽  
Brightness Temperatures ◽  
Eclipse Observations ◽  
Theoretical Predictions ◽  
The Difference ◽  
Hot Jupiter

A key hypothesis in the field of exoplanet atmospheres is the trend of atmospheric thermal structure with planetary equilibrium temperature. We explore this trend and report here the first statistical detection of a transition in the near-infrared atmospheric emission between hot and ultra-hot Jupiters. We measure this transition using secondary eclipse observations and interpret this phenomenon as changes in atmospheric properties, and more specifically in terms of transition from non-inverted to inverted thermal profiles. We examine a sample of 78 hot Jupiters with secondary eclipse measurements at 3.6 and 4.5 μm measured with Spitzer Infrared Array Camera. We calculate the planetary brightness temperatures using PHOENIX models to correct for the stellar flux. We measure the deviation of the data from the blackbody, which we define as the difference between the observed 4.5 μm eclipse depth and that expected at this wavelength based on the brightness temperature measured at 3.6 μm. We study how the deviation between 3.6 and 4.5 μm changes with theoretical predictions with equilibrium temperature and incoming stellar irradiation. We reveal a clear transition in the observed emission spectra of the hot Jupiter population at 1660 ± 100 K in the zero albedo, full redistribution equilibrium temperature. We find the hotter exoplanets have even hotter daysides at 4.5 μm compared to 3.6 μm, which manifests as an exponential increase in the emitted power of the planets with stellar insolation. We propose that the measured transition is a result of seeing carbon monoxide in emission due to the formation of temperature inversions in the atmospheres of the hottest planets. These thermal inversions could be caused by the presence of atomic and molecular species with high opacities in the optical and/or the lack of cooling species. Our findings are in remarkable agreement with a new grid of 1D radiative and convective models varying metallicity, carbon to oxygen ratio (C/O), surface gravity, and stellar effective temperature. We find that the population of hot Jupiters statistically disfavors high C/O planets (C/O ≥ 0.85).

scholarly journals A hot Jupiter spectral sequence with evidence for compositional diversity

2020 ◽  
Author(s):  
Megan Mansfield ◽  
Michael Line ◽  
Jacob Bean ◽  
Jonathan Fortney ◽  
Vivien Parmentier ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Emission Spectra ◽  
Brown Dwarfs ◽  
Population Level ◽  
Theoretical Models ◽  
Elemental Abundance ◽  
Hot Jupiters ◽  
Irradiation Level ◽  
Compositional Diversity ◽  
Hot Jupiter

Abstract The emergent spectra of close-in, giant exoplanets ("hot Jupiters") are believed to be distinct from those of young gas giants and brown dwarfs with similar effective temperatures because these objects are primarily heated from above by their host stars rather than internally from the release of energy from their formation (Showman et al. 2020). Theoretical models predict a continuum of dayside spectra for hot Jupiters as a function of irradiation level, with the coolest planets having absorption features in their spectra, intermediate-temperature planets having emission features due to thermal inversions, and the hottest planets having blackbody-like spectra due to molecular dissociation and continuum opacity from the H- ion (Fortney et al. 2008, Parmentier et al. 2018, Arcangeli et al. 2018). Absorption and emission features have been detected in the spectra of a number of individual hot Jupiters (Kreidberg et al. 2014, Mikal-Evans et al. 2020), and population-level trends have been observed in photometric measurements (Keating et al. 2019, Baxter et al. 2020, Garhart et al. 2020, Dransfield et al. 2020). However, there has been no unified, population-level study of the thermal emission spectra of hot Jupiters such as has been done for brown dwarfs (Manjavacas et al. 2019) and transmission spectra of hot Jupiters (Sing et al. 2016). Here we show that hot Jupiter secondary eclipse spectra centered around a water absorption band at 1.4 microns follow a common trend in water feature strength with temperature. The observed trend is broadly consistent with the predictions of self-consistent one-dimensional models for how the thermal structures of solar composition planets vary with irradiation level. Nevertheless, the ensemble of planets exhibits significant scatter around the mean trend. The spread can be accounted for if the planets have modest variations in metallicity and/or elemental abundance ratios, which is expected from planet formation models (Mordasini et al. 2016, Ali-Dib et al. 2017, Madhusudhan et al. 2017, Cridland et al. 2019).

scholarly journals Understanding the atmospheric properties and chemical composition of the ultra-hot Jupiter HAT-P-7b

2019 ◽  
Vol 631 ◽  
pp. A79 ◽  
Author(s):  
Ch. Helling ◽  
N. Iro ◽  
L. Corrales ◽  
D. Samra ◽  
K. Ohno ◽  
...  
Keyword(s):  
Gas Phase ◽  
Local Equilibrium ◽  
Theoretical Models ◽  
Cloud Formation ◽  
Phase Curve ◽  
Large Temperature ◽  
Global Changes ◽  
Hot Jupiters ◽  
Dependent Observations ◽  
Hot Jupiter

Context. Of the presently known ≈3900 exoplanets, sparse spectral observations are available for ≈100. Ultra-hot Jupiters have recently attracted interest from observers and theoreticians alike, as they provide observationally accessible test cases. Confronting detailed theoretical models with observations is of preeminent importance in preparation for upcoming space-based telescopes. Aims. We aim to study cloud formation on the ultra-hot Jupiter HAT-P-7b, the resulting composition of the local gas phase, and how their global changes affect wavelength-dependent observations utilised to derive fundamental properties of the planet. Methods. We apply a hierarchical modelling approach as a virtual laboratory to study cloud formation and gas-phase chemistry. We utilise 97 vertical 1D profiles of a 3D GCM for HAT-P-7b to evaluate our kinetic cloud formation model consistently with the local equilibrium gas-phase composition. We use maps and slice views to provide a global understanding of the cloud and gas chemistry. Results. The day/night temperature difference on HAT-P-7b (ΔT ≈ 2500 K) causes clouds to form on the nightside (dominated by H2/He) while the dayside (dominated by H/He) retains cloud-free equatorial regions. The cloud particles vary in composition and size throughout the vertical extension of the cloud, but also globally. TiO2[s]/Al2O3[s]/CaTiO3[s]-particles of cm-sized radii occur in the higher dayside-latitudes, resulting in a dayside dominated by gas-phase opacity. The opacity on the nightside, however, is dominated by 0.01…0.1μm particles made of a material mix dominated by silicates. The gas pressure at which the atmosphere becomes optically thick is ~10−4 bar in cloudy regions, and ~0.1 bar in cloud-free regions. Conclusions. HAT-P-7b features strong morning/evening terminator asymmetries, providing an example of patchy clouds and azimuthally-inhomogeneous chemistry. Variable terminator properties may be accessible by ingress/egress transmission photometry (e.g., CHEOPS and PLATO) or spectroscopy. The large temperature differences of ≈2500 K result in an increasing geometrical extension from the night- to the dayside. The H2O abundance at the terminator changes by <1 dex with altitude and ≲0.3 dex (a factor of 2) across the terminator for a given pressure, indicating that H2O abundances derived from transmission spectra can be representative of the well-mixed metallicity at P ≳ 10 bar. We suggest the atmospheric C/O as an important tool to trace the presence and location of clouds in exoplanet atmospheres. The atmospheric C/O can be sub- and supersolar due to cloud formation. Phase curve variability of HAT-P-7b is unlikely to be caused by dayside clouds.

Longitudinally Resolved Phase-curve Retrievals of WASP-43b

2021 ◽  
Author(s):  
Patricio E. Cubillos ◽  
Dylan Keating ◽  
Nicolas Cowan ◽  
Johanna Vos ◽  
Ben Burningham ◽  
...  
Keyword(s):  
Emission Spectra ◽  
Phase Curve ◽  
Night Temperature ◽  
Vertical Temperature ◽  
Linear Combinations ◽  
Phase Measurements ◽  
Thermal Phase ◽  
Longitudinal Variations ◽  
Phase Variations ◽  
The Impact

&lt;p&gt;Thermal phase variations of exoplanets are a patent testimony of their multidimensional nature: day-to-night temperature contrasts range from hundreds to thousands of degrees. &amp;#160;Nonetheless, the spectra of these planets have typically been fit using 1D retrieval codes that only account for vertical temperature gradients. &amp;#160;Recent multi-dimensional retrieval schemes are generally based on linear combinations of 1D models, which are more liable to degeneracies and more computationally demanding. &amp;#160;Here we present an alternative: phase-dependent spectral observations are inverted to produce longitudinally resolved spectra that can then be fitted using standard 1D spectral retrieval codes. We test this scheme on the phase-resolved spectra of WASP-43b and on simulated JWST observations using the open-source Pyrat Bay retrieval framework. &amp;#160;We show that 1D spectral retrievals on longitudinally resolved spectra are more accurate than applying 1D spectral retrieval codes to disk-integrated emission spectra, highlighting the impact of longitudinal variations in composition in addition to temperature. &amp;#160;In particular, we find that JWST phase measurements of WASP-43b should be treated with longitudinally resolved spectral retrieval.&lt;/p&gt;

scholarly journals Mapping the Pressure-dependent Day–Night Temperature Contrast of a Strongly Irradiated Atmosphere with HST Spectroscopic Phase Curve

2021 ◽  
Vol 163 (1) ◽  
pp. 8
Author(s):  
Ben W. P. Lew ◽  
Dániel Apai ◽  
Yifan Zhou ◽  
Mark Marley ◽  
L. C. Mayorga ◽  
...  
Keyword(s):  
White Dwarf ◽  
Near Infrared ◽  
Brown Dwarfs ◽  
Phase Curve ◽  
Brown Dwarf ◽  
Night Temperature ◽  
Flux Variation ◽  
Hot Jupiters ◽  
Temperature Contrast ◽  
Hot Jupiter

Abstract Many brown dwarfs are on ultrashort-period and tidally locked orbits around white dwarf hosts. Because of these small orbital separations, the brown dwarfs are irradiated at levels similar to hot Jupiters. Yet, they are easier to observe than hot Jupiters because white dwarfs are fainter than main-sequence stars at near-infrared wavelengths. Irradiated brown dwarfs are, therefore, ideal hot Jupiter analogs for studying the atmospheric response under strong irradiation and fast rotation. We present the 1.1–1.67 μm spectroscopic phase curve of the irradiated brown dwarf (SDSS1411-B) in the SDSS J141126.20 + 200911.1 brown dwarf–white dwarf binary with the near-infrared G141 grism of the Hubble Space Telescope Wide Field Camera 3. SDSS1411-B is a 50M Jup brown dwarf with an irradiation temperature of 1300 K and has an orbital period of 2.02864 hr. Our best-fit model suggests a phase-curve amplitude of 1.4% and places an upper limit of 11° for the phase offset from the secondary eclipse. After fitting the white dwarf spectrum, we extract the phase-resolved brown dwarf emission spectra. We report a highly wavelength-dependent day–night spectral variation, with a water-band flux variation of about 360% ± 70% and a comparatively small J-band flux variation of 37% ± 2%. By combining the atmospheric modeling results and the day–night brightness temperature variations, we derive a pressure-dependent temperature contrast. We discuss the difference in the spectral features of SDSS1411-B and hot Jupiter WASP-43b, as well as the lower-than-predicted day–night temperature contrast of J4111-BD. Our study provides the high-precision observational constraints on the atmospheric structures of an irradiated brown dwarf at different orbital phases.

scholarly journals Detection of the phase curve and occultation of WASP-100b with TESS

2020 ◽  
Vol 494 (3) ◽  
pp. 4077-4089 ◽  
Author(s):  
Tiffany Jansen ◽  
David Kipping
Keyword(s):  
Phase Shift ◽  
Low Frequency ◽  
Notch Filter ◽  
Null Model ◽  
Phase Curve ◽  
Hot Jupiters ◽  
Thermal Phase ◽  
Orbital Phase ◽  
Occultation Data ◽  
Geometric Albedo

ABSTRACT We report the detection of the full orbital phase curve and occultation of the hot-Jupiter WASP-100b using TESS photometry. The phase curve is isolated by suppressing low-frequency stellar and instrumental modes using both a non-parametric harmonic notch filter (phasma) and semi-sector long polynomials. This yields a phase-curve signal of (73 ± 9) ppm amplitude, preferred over a null-model by ΔBIC = 25, indicating very strong evidence for an observed effect. We recover the occultation event with a suite of five temporally localized tools, including Gaussian processes and cosine filtering. This allows us to infer an occultation depth of (100 ± 14) ppm, with an additional ±16 ppm systematic error from the differences between methods. We regress a model including atmospheric reflection, emission, ellipsoidal variations, and Doppler beaming to the combined phase-curve and occultation data. This allows us to infer that WASP-100b has a geometric albedo of $A_g = 0.16^{+0.04}_{-0.03}$ in the TESS bandpass, with a maximum dayside brightness temperature of (2710 ± 100) K and a warm nightside temperature of $(2380^{+170}_{-200})$ K. Additionally, we find evidence that WASP-100b has a high thermal redistribution efficiency, manifesting as a substantial eastward hotspot offset of $(71^{+2}_{-4})^{\circ }$. These results present the first measurement of a thermal phase shift among the phase curves observed by TESS so far, and challenge the predicted efficiency of heat transport in the atmospheres of ultra-hot-Jupiters.

scholarly journals Optical phase curve of the ultra-hot Jupiter WASP-121b

2020 ◽  
Vol 637 ◽  
pp. A36 ◽  
Author(s):  
V. Bourrier ◽  
D. Kitzmann ◽  
T. Kuntzer ◽  
V. Nascimbeni ◽  
M. Lendl ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Heat Transport ◽  
Temperature Inversion ◽  
Phase Curve ◽  
Optical Photometry ◽  
Optical Phase ◽  
Strong Deviation ◽  
Hot Jupiter

We present the analysis of TESS optical photometry of WASP-121b, which reveals the phase curve of this transiting ultra-hot Jupiter. Its hotspot is located at the sub-stellar point, showing inefficient heat transport from the dayside (2870 ± 50 K) to the nightside (<2500 K at 3σ) at the altitudes probed by TESS. The TESS eclipse depth, measured at the shortest wavelength to date for WASP-121b, confirms the strong deviation from blackbody planetary emission. Our atmospheric retrieval on the complete emission spectrum supports the presence of a temperature inversion, which can be explained by the presence of VO and possibly TiO and FeH. The strong planetary emission at short wavelengths could arise from an H− continuum.

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