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 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.

scholarly journals Following the TraCS of exoplanets with Pan-Planets: Wendelstein-1b and Wendelstein-2b

2020 ◽  
Vol 639 ◽  
pp. A130
Author(s):  
C. Obermeier ◽  
J. Steuer ◽  
H. Kellermann ◽  
R. P. Saglia ◽  
Th. Henning ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Radial Velocity ◽  
Thermal Emission ◽  
Dwarf Star ◽  
Statistical Characterization ◽  
Hot Jupiters ◽  
Eclipse Observations ◽  
Short Period ◽  
Hot Jupiter

Hot Jupiters seem to get rarer with decreasing stellar mass. The goal of the Pan-Planets transit survey was the detection of such planets and a statistical characterization of their frequency. Here, we announce the discovery and validation of two planets found in that survey, Wendelstein-1b and Wendelstein-2b, which are two short-period hot Jupiters that orbit late K host stars. We validated them both by the traditional method of radial velocity measurements with the HIgh Resolution Echelle Spectrometer and the Habitable-zone Planet Finder instruments and then by their Transit Color Signature (TraCS). We observed the targets in the wavelength range of 4000−24 000 Å and performed a simultaneous multiband transit fit and additionally determined their thermal emission via secondary eclipse observations. Wendelstein-1b is a hot Jupiter with a radius of 1.0314−0.0061+0.0061 RJ and mass of 0.592−0.129+0.0165 MJ, orbiting a K7V dwarf star at a period of 2.66 d, and has an estimated surface temperature of about 1727−90+78 K. Wendelstein-2b is a hot Jupiter with a radius of 1.1592−0.0210+0.0204 RJ and a mass of 0.731−0.311+0.0541 MJ, orbiting a K6V dwarf star at a period of 1.75 d, and has an estimated surface temperature of about 1852−140+120 K. With this, we demonstrate that multiband photometry is an effective way of validating transiting exoplanets, in particular for fainter targets since radial velocity follow-up becomes more and more costly for those targets.

scholarly journals Colour–colour and colour–magnitude diagrams for hot Jupiters

2020 ◽  
Vol 494 (4) ◽  
pp. 4939-4949 ◽  
Author(s):  
G Melville ◽  
L Kedziora-Chudczer ◽  
J Bailey
Keyword(s):  
Measurement Errors ◽  
Near Infrared ◽  
Emission Spectra ◽  
Brown Dwarfs ◽  
Low Gravity ◽  
Hot Jupiters ◽  
Substellar Objects ◽  
Solar Metallicity ◽  
Ir Bands ◽  
Individual Objects

ABSTRACT We use ground-based and space-based eclipse measurements for the near-infrared (IR) bands (JHKs) and Spitzer 3.6- and 4.5-μm bands to construct colour–colour and colour–magnitude diagrams for hot Jupiters. We compare the results with previous observations of substellar objects and find that hot Jupiters, when corrected for their inflated radii, lie near the blackbody line and in the same region of the colour–magnitude diagrams as brown dwarfs, including low-gravity dwarfs that have been previously suggested as exoplanet analogues. We use theoretical emission spectra to investigate the effects of different metallicity, C/O ratios, and temperatures on the IR colours. In general, we find that while differences in C/O ratio and metallicity do correspond to different locations on these diagrams, the measurement errors are too large to use this method to put strong constraints on the composition of individual objects. However, as a class, hot Jupiters cluster around the location expected for solar metallicity and C/O ratio.

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 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.

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 Why is it So Hot in Here? Exploring Population Trends in Spitzer Thermal Emission Observations of Hot Jupiters Using Planet-specific, Self-consistent Atmospheric Models

2021 ◽  
Vol 923 (2) ◽  
pp. 242
Author(s):  
Jayesh M. Goyal ◽  
Nikole K. Lewis ◽  
Hannah R. Wakeford ◽  
Ryan J. MacDonald ◽  
Nathan J. Mayne
Keyword(s):  
Thermal Emission ◽  
Population Level ◽  
Equilibrium Temperature ◽  
Current Data ◽  
Population Trends ◽  
Chemical Compositions ◽  
Atmospheric Models ◽  
Hot Jupiters ◽  
Eclipse Observations ◽  
Self Consistent

Abstract Thermal emission has now been observed from dozens of exoplanet atmospheres, opening the gateway to population-level characterization. Here, we provide theoretical explanations for observed trends in Spitzer IRAC channel 1 (3.6 μm) and channel 2 (4.5 μm) photometric eclipse depths (EDs) across a population of 34 hot Jupiters. We apply planet-specific, self-consistent atmospheric models, spanning a range of recirculation factors, metallicities, and C/O ratios, to probe the information content of Spitzer secondary eclipse observations across the hot-Jupiter population. We show that most hot Jupiters are inconsistent with blackbodies from Spitzer observations alone. We demonstrate that the majority of hot Jupiters are consistent with low-energy redistribution between the dayside and nightside (hotter dayside than expected with efficient recirculation). We also see that high-equilibrium temperature planets (T eq ≥ 1800 K) favor inefficient recirculation in comparison to the low temperature planets. Our planet-specific models do not reveal any definitive population trends in metallicity and C/O ratio with current data precision, but more than 59% of our sample size is consistent with the C/O ratio ≤ 1 and 35% are consistent with whole range (0.35 ≤ C/O ≤ 1.5). We also find that for most of the planets in our sample, 3.6 and 4.5 μm model EDs lie within ±1σ of the observed EDs. Intriguingly, few hot Jupiters exhibit greater thermal emission than predicted by the hottest atmospheric models (lowest recirculation) in our grid. Future spectroscopic observations of thermal emission from hot Jupiters with the James Webb Space Telescope will be necessary to robustly identify population trends in chemical compositions with its increased spectral resolution, range, and data precision.

Fe I and Fe II in the atmosphere of Ultra-hot Jupiter MASCARA-2b

2020 ◽  
Author(s):  
Monika Stangret ◽  
Núria Casasayas-Barris ◽  
Enric Palle ◽  
Fei Yan ◽  
Alejandro Sánchez-López ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Theoretical Models ◽  
High Resolution Spectroscopy ◽  
Atmospheric Transmission ◽  
Hot Jupiters ◽  
Residual Noise ◽  
The Earth ◽  
Exoplanetary Atmospheres ◽  
Host Stars ◽  
Hot Jupiter

&lt;p&gt;Thanks to the different Doppler velocities of the Earth, the&amp;#160;host star and the planet using high-resolution spectroscopy we&amp;#160;are able to detect and characterise exoplanetary atmospheres.&amp;#160;Exoplanetary signal is buried in the residual noise, however&amp;#160;by preforming cross-correlation of atmospheric transmission&amp;#160;model and hundreds of atmospheric lines the signal can be&amp;#160;increase. Studying the atmospheres of ultra-hot Jupiters,&amp;#160;objects with the temperature higher than 2200K which orbit&amp;#160;close to their host stars, gives us great laboratory to study&amp;#160;chemistry of the exoplanets. MASCARA-2b also known as KELT-20b&amp;#160;with the temperature of 2230 K is a perfect example of ultra&amp;#160;hot Jupiter. We studied this object using three transit&amp;#160;observations obtained with HARPS-North. Using cross-correlation&amp;#160;method we detected strong absorption of Fe I and&amp;#160;FeII, which agrees with theoretical models. Additionally,&amp;#160;because of the fast rotation of the star, the crosscorrelation&amp;#160;residuals show strong Rossiter-MacLaughlin effect.&lt;/p&gt;

scholarly journals Implications of three-dimensional chemical transport in hot Jupiter atmospheres: Results from a consistently coupled chemistry-radiation-hydrodynamics model

2020 ◽  
Vol 636 ◽  
pp. A68 ◽  
Author(s):  
Benjamin Drummond ◽  
Eric Hébrard ◽  
Nathan J. Mayne ◽  
Olivia Venot ◽  
Robert J. Ridgway ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Chemical Species ◽  
Emission Spectra ◽  
Chemical Transport ◽  
Radiation Hydrodynamics ◽  
Atmospheric Flow ◽  
Hot Jupiters ◽  
Chemical Structures ◽  
Hot Jupiter

We present results from a set of simulations using a fully coupled three-dimensional (3D) chemistry-radiation-hydrodynamics model and investigate the effect of transport of chemical species by the large-scale atmospheric flow in hot Jupiter atmospheres. We coupled a flexible chemical kinetics scheme to the Met Office Unified Model, which enables the study of the interaction of chemistry, radiative transfer, and fluid dynamics. We used a newly-released “reduced” chemical network, comprising 30 chemical species, that was specifically developed for its application in 3D atmosphere models. We simulated the atmospheres of the well-studied hot Jupiters HD 209458b and HD 189733b which both have dayside–nightside temperature contrasts of several hundred Kelvin and superrotating equatorial jets. We find qualitatively quite different chemical structures between the two planets, particularly for methane (CH4), when advection of chemical species is included. Our results show that consideration of 3D chemical transport is vital in understanding the chemical composition of hot Jupiter atmospheres. Three-dimensional mixing leads to significant changes in the abundances of absorbing gas-phase species compared with what would be expected by assuming local chemical equilibrium, or from models including 1D – and even 2D – chemical mixing. We find that CH4, carbon dioxide (CO2), and ammonia (NH3) are particularly interesting as 3D mixing of these species leads to prominent signatures of out-of-equilibrium chemistry in the transmission and emission spectra, which are detectable with near-future instruments.

scholarly journals Investigating hot-Jupiter inflated radii with hierarchical Bayesian modelling

2018 ◽  
Vol 616 ◽  
pp. A76 ◽  
Author(s):  
Marko Sestovic ◽  
Brice-Olivier Demory ◽  
Didier Queloz
Keyword(s):  
Large Fraction ◽  
Population Level ◽  
Mass Range ◽  
Hierarchical Bayesian ◽  
Incident Flux ◽  
Hot Jupiters ◽  
Probabilistic Relation ◽  
Relationship Of ◽  
The Relationship ◽  
Level Analysis

Context. As of today, hundreds of hot Jupiters have been found, yet the inflated radii of a large fraction of them remain unexplained. A number of mechanisms have been proposed to explain these anomalous radii, however most of these can only work under certain conditions and may not be sufficient to explain the most extreme cases. It is still unclear whether a single mechanism can sufficiently explain the entire distribution of radii, or whether a combination of these mechanisms is needed. Aims. We seek to understand the relationship of radius with stellar irradiation and mass and to find the range of masses over which hot Jupiters are inflated. We also aim to find the intrinsic physical scatter in their radii, caused by unobservable parameters, and to constrain the fraction of hot Jupiters that exhibit inflation. Methods. By constructing a hierarchical Bayesian model, we inferred the probabilistic relation between planet radius, mass, and incident flux for a sample of 286 gas giants. We separately incorporated the observational uncertainties of the data and the intrinsic physical scatter in the population. This allowed us to treat the intrinsic physical scatter in radii, due to latent parameters such as the heavy element fraction, as a parameter to be inferred. Results. We find that the planetary mass plays a key role in the inflation extent and that planets in the range ~0.37−0.98  MJ show the most inflated radii. At higher masses, the radius response to incident flux begins to decrease. Below a threshold of 0.37 ± 0.03  MJ we find that giant exoplanets as a population are unable to maintain inflated radii ≿1.4  RJ but instead exhibit smaller sizes as the incident flux is increased beyond 106 W m−2. We also find that below 1  MJ, there is a cut-off point at high incident flux beyond which we find no more inflated planets, and that this cut-off point decreases as the mass decreases. At incident fluxes higher than ~1.6 × 106 W m−2 and in a mass range 0.37−0.98  MJ, we find no evidence for a population of non-inflated hot Jupiters. Our study sheds a fresh light on one of the key questions in the field and demonstrates the importance of population-level analysis to grasp the underlying properties of exoplanets.

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