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

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.

Download Full-text

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

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037715 ◽

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.

Download Full-text

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

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937394 ◽

2020 ◽

Vol 639 ◽

pp. A36 ◽

Cited By ~ 3

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).

Download Full-text

A hot Jupiter spectral sequence with evidence for compositional diversity

10.21203/rs.3.rs-93825/v1 ◽

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).

Download Full-text

A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038294 ◽

2020 ◽

Vol 640 ◽

pp. L5 ◽

Cited By ~ 4

Author(s):

F. Yan ◽

E. Pallé ◽

A. Reiners ◽

K. Molaverdikhani ◽

N. Casasayas-Barris ◽

...

Keyword(s):

Thermal Emission ◽

Giant Planet ◽

Chemical Species ◽

Temperature Inversion ◽

Equilibrium Temperature ◽

Spectral Lines ◽

High Spectral Resolution ◽

Correlation Technique ◽

Hot Jupiters ◽

Solar Metallicity

Temperature inversion layers are predicted to be present in ultra-hot giant planet atmospheres. Although such inversion layers have recently been observed in several ultra-hot Jupiters, the chemical species responsible for creating the inversion remain unidentified. Here, we present observations of the thermal emission spectrum of an ultra-hot Jupiter, WASP-189b, at high spectral resolution using the HARPS-N spectrograph. Using the cross-correlation technique, we detect a strong Fe I signal. The detected Fe I spectral lines are found in emission, which is direct evidence of a temperature inversion in the planetary atmosphere. We further performed a retrieval on the observed spectrum using a forward model with an MCMC approach. When assuming a solar metallicity, the best-fit result returns a temperature of 4320−100+120 K at the top of the inversion, which is significantly hotter than the planetary equilibrium temperature (2641 K). The temperature at the bottom of the inversion is determined as 2200−800+1000 K. Such a strong temperature inversion is probably created by the absorption of atomic species like Fe I.

Download Full-text

Investigating hot-Jupiter inflated radii with hierarchical Bayesian modelling

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731454 ◽

2018 ◽

Vol 616 ◽

pp. A76 ◽

Cited By ~ 17

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.

Download Full-text

NEAR-INFRARED THERMAL EMISSION DETECTIONS OF A NUMBER OF HOT JUPITERS AND THE SYSTEMATICS OF GROUND-BASED NEAR-INFRARED PHOTOMETRY

The Astrophysical Journal ◽

10.1088/0004-637x/802/1/28 ◽

2015 ◽

Vol 802 (1) ◽

pp. 28 ◽

Cited By ~ 34

Author(s):

Bryce Croll ◽

Loic Albert ◽

Ray Jayawardhana ◽

Michael Cushing ◽

Claire Moutou ◽

...

Keyword(s):

Near Infrared ◽

Thermal Emission ◽

Infrared Photometry ◽

Hot Jupiters

Download Full-text

TOI-150b and TOI-163b: two transiting hot Jupiters, one eccentric and one inflated, revealed by TESS near and at the edge of the JWST CVZ

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2433 ◽

2019 ◽

Vol 490 (1) ◽

pp. 1094-1110 ◽

Cited By ~ 3

Author(s):

Diana Kossakowski ◽

Néstor Espinoza ◽

Rafael Brahm ◽

Andrés Jordán ◽

Thomas Henning ◽

...

Keyword(s):

High Resolution ◽

Time Scale ◽

High Resolution Spectroscopy ◽

Spin Orbit ◽

Eccentric Orbit ◽

Hot Jupiters ◽

Eclipse Observations ◽

James Webb Space Telescope ◽

Hot Jupiter

Abstract We present the discovery of TYC9191-519-1b (TOI-150b, TIC 271893367) and HD271181b (TOI-163b, TIC 179317684), two hot Jupiters initially detected using 30-min cadence Transiting Exoplanet Survey Satellite (TESS) photometry from Sector 1 and thoroughly characterized through follow-up photometry (CHAT, Hazelwood, LCO/CTIO, El Sauce, TRAPPIST-S), high-resolution spectroscopy (FEROS, CORALIE), and speckle imaging (Gemini/DSSI), confirming the planetary nature of the two signals. A simultaneous joint fit of photometry and radial velocity using a new fitting package juliet reveals that TOI-150b is a $1.254\pm 0.016\ \rm {R}_ \rm{J}$, massive ($2.61^{+0.19}_{-0.12}\ \rm {M}_ \rm{J}$) hot Jupiter in a 5.857-d orbit, while TOI-163b is an inflated ($R_ \rm{P}$ = $1.478^{+0.022}_{-0.029} \,\mathrm{ R}_ \rm{J}$, $M_ \rm{P}$ = $1.219\pm 0.11 \, \rm{M}_ \rm{J}$) hot Jupiter on a P = 4.231-d orbit; both planets orbit F-type stars. A particularly interesting result is that TOI-150b shows an eccentric orbit ($e=0.262^{+0.045}_{-0.037}$), which is quite uncommon among hot Jupiters. We estimate that this is consistent, however, with the circularization time-scale, which is slightly larger than the age of the system. These two hot Jupiters are both prime candidates for further characterization – in particular, both are excellent candidates for determining spin-orbit alignments via the Rossiter–McLaughlin (RM) effect and for characterizing atmospheric thermal structures using secondary eclipse observations considering they are both located closely to the James Webb Space Telescope (JWST) Continuous Viewing Zone (CVZ).

Download Full-text

Secondary eclipse of the hot Jupiter WASP-121b at 2 μm

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834325 ◽

2019 ◽

Vol 625 ◽

pp. A80 ◽

Cited By ~ 8

Author(s):

Géza Kovács ◽

Tamás Kovács

Keyword(s):

Near Infrared ◽

Infrared Emission ◽

Current Data ◽

Emission Analysis ◽

Hot Jupiters ◽

Occultation Data ◽

The One ◽

Near Infrared Emission ◽

Absorption Features ◽

Hot Jupiter

Ground-based observations of the secondary eclipse in the 2MASS K band are presented for the hot Jupiter WASP-121b. These are the first occultation observations of an extrasolar planet that were carried out with an instrument attached to a 1 m class telescope (the SMARTS 1.3 m). We find a highly significant eclipse depth of (0.228 ± 0.023)%. Together with other planet atmosphere measurements, including the Hubble Space Telescope near-infrared emission spectrum, current data support more involved atmosphere models with species producing emission and absorption features, rather than simple smooth blackbody emission. Analysis of the time difference between the primary and secondary eclipses and the durations of these events yields an eccentricity of e = 0.0207 ± 0.0153, which is consistent with the earlier estimates of low or zero eccentricity, but with a smaller error. Comparing the observed occultation depth in the K band with the one derived under the assumption of zero Bond albedo and full heat redistribution, we find that WASP-121b has a deeper observed occultation depth than predicted. Together with the sample of 31 systems with K-band occultation data, this observation lends further support to the idea of inefficient heat transport between the day and night sides for most of the hot Jupiters.

Download Full-text

The Application of the Study of Galaxies Associated With Quasars to Observational Cosmology

Symposium - International Astronomical Union ◽

10.1017/s0074180900159777 ◽

1987 ◽

Vol 124 ◽

pp. 685-689

Author(s):

H.K.C. Yee

Keyword(s):

Galaxy Clusters ◽

Count Data ◽

Luminosity Function ◽

Current Data ◽

Observational Cosmology ◽

Direct Imaging ◽

Large Uncertainty ◽

Self Consistent ◽

Galaxy Count

CCD direct imaging of fields around quasars is used as a method for locating galaxy clusters and groups associated with quasars. Average galaxy counts in the sky obtained from control fields are used to correct for background galaxies in the quasar fields. This correction allows one to derive the luminosity function (LF) of the associated galaxies at the redshifts of the quasars. It is demonstrated that using the derived LF and average galaxy count data, self-consistent models of the evolution of the LF and galaxy counts can be obtained. Current data are best fitted, with a large uncertainty, by a qo between 0.0 and 0.5 and an evolution in M* of −0.9±0.5 mag. It is found that the average environment of radio-loud quasars at z∼0.6 is about three times richer in galaxies than that of quasars at z∼0.4.

Download Full-text

NEUTRINO EMISSION FROM DARK MATTER ANNIHILATION/DECAY IN LIGHT OF COSMIC e± AND $\bar{p}$ DATA

International Journal of Modern Physics A ◽

10.1142/s0217751x12500248 ◽

2012 ◽

Vol 27 (06) ◽

pp. 1250024 ◽

Cited By ~ 2

Author(s):

JIE LIU ◽

QIANG YUAN ◽

XIAOJUN BI ◽

HONG LI ◽

XINMIN ZHANG

Keyword(s):

Dark Matter ◽

Branching Ratio ◽

Cosmic Ray ◽

Current Data ◽

Neutrino Emission ◽

Dark Matter Annihilation ◽

Text Data ◽

Self Consistent ◽

Γ Rays ◽

Global Fitting

A self-consistent global fitting method based on the Markov Chain Monte Carlo technique to study the dark matter (DM) property associated with the cosmic ray electron/positron excesses was developed in our previous work. In this work we further improve the previous study to include the hadronic branching ratio of DM annihilation/decay. The PAMELA [Formula: see text] data are employed to constrain the hadronic branching ratio. We find that the 95% (2σ) upper limits of the quark branching ratio allowed by the PAMELA [Formula: see text] data is ~0.032 for DM annihilation and ~0.044 for DM decay, respectively. This result shows that the DM coupling to pure leptons is indeed favored by the current data. Based on the global fitting results, we further study the neutrino emission from DM in the galactic center. Our predicted neutrino flux is some smaller than previous works since the constraint from γ-rays is involved. However, it is still capable to be detected by the forthcoming neutrino detector such as IceCube. The improved points of the present study compared with previous works include: (1) the DM parameters, both the particle physical ones and astrophysical ones, are derived in a global fitting way, (2) constraints from various species of data sets, including γ-rays and antiprotons are included, and (3) the expectation of neutrino emission is fully self-consistent.

Download Full-text