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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Clear-Sky Probability for the 2023 Annular Solar Eclipse and the 2024 Total Solar Eclipse Using the NREL National Solar Radiation Database

The National Renewable Energy Laboratory (NREL) and collaborators have created a clear-sky probability analysis to help guide viewers to the 2023 annular solar eclipse and the 2024 total solar eclipse. Using cloud and solar data from the NREL National Solar Radiation Database (NSRDB), the analysis provides cloudless-sky probabilities specific to the date, time, and location of each eclipse with a 4-km resolution. Though not intended to be an eclipse weather forecast, the detailed maps can help guide eclipse enthusiasts to likely optimal viewing locations. Additionally, high-resolution data are presented for the centerline of the path of each eclipse, representing the likelihood for cloudless skies and atmospheric clarity. The NSRDB provides industry, academia, and other stakeholders with high-resolution solar irradiance data to support feasibility analyses for photovoltaic and concentrating solar power generation projects.

14 SOLAR ENERGY↗
DOE OSTI2021

Identifying Periodic Variable Stars and Eclipsing Binary Systems with Long-term Las Cumbres Observatory Photometric Monitoring of ZTF J0139+5245

We present the results of our search for variable stars using the long-term Las Cumbres Observatory (LCO) monitoring of white dwarf ZTF J0139+5245 with the two 1.0 m telescope nodes located at McDonald Observatory using the Sinistro imaging instrument. In this search, we find 38 variable sources, of which 27 are newly discovered or newly classified (71%) based on comparisons with previously published catalogs, thereby increasing the number of detections in the field of view under consideration by a factor of ≈2.5. We find that the improved photometric precision per exposure due to longer exposure time for LCO images combined with the greater time sampling of LCO photometry enables us to increase the total number of detections in this field of view. Each LCO image covers a field of view of 26' × 26' and observes a region close to the Galactic plane (b = -9.°4) abundant in stars with an average stellar density of ≈8 arcmin{sup -2}. We perform aperture photometry and Fourier analysis on over 2000 stars across 1560 LCO images spanning 537 days to find 28 candidate BY Draconis variables, three candidate eclipsing binaries of type EA, and seven candidate eclipsing binaries of type EW. In assigning preliminary classifications to our detections, we demonstrate the applicability of the Gaia color–magnitude diagram as a powerful classification tool for variable-star studies.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Observations of the Marine Atmospheric Boundary Layer’s Response to a Solar Eclipse

The atmospheric response to the solar eclipse of 8 April 2024 in North America is investigated with a specific focus on the marine atmospheric boundary layer (MABL). We leverage measurements collected during the Third Wind Forecast Improvement Project (WFIP3), including Doppler lidars, sonic anemometers, and thermodynamic profiler data to investigate the atmospheric response across sites that experienced partial eclipse conditions with nearly 90% obscuration. Using these measurements, we examine eclipse-induced changes in key meteorological parameters, such as temperature, wind speed, and turbulent fluxes. Most previous eclipse studies have been conducted over land, whereas this study provides new observations for both coastal and marine environments, offering additional insight into eclipse-driven variability in the MABL. The findings confirm a notable decrease in downwelling shortwave radiation during the eclipse, which results in rapid cooling of surface air. The temperature reduction ranges from $1.2^\circ \text {C}$ to $1.4^\circ \text {C}$ in coastal regions and from $0.3^\circ \text {C}$ to $0.5^\circ \text {C}$ over the ocean. This analysis suggests that the MABL’s higher thermal inertia compared to coastal regions moderates the temperature decrease during the eclipse. Wind speed exhibits a more complex behavior, as it is influenced by both the MABL and preexisting synoptic conditions. Although a reduction in wind speed is observable up to approximately 140 m above ground level (AGL) at more inland sites, at other locations closer to the coast, this reduction is constrained to the lowest 100 m AGL. Turbulence parameters retrieved from sonic anemometers, such as turbulence kinetic energy, turbulent heat flux, and friction velocity, decrease during the eclipse at coastal sites, accompanied by a brief transition of atmospheric stability from unstable to neutral or weakly stable conditions. For the open-ocean sites, the variability in turbulence statistics and atmospheric stability is minimal during the occurrence of the eclipse.

16 TIDAL AND WAVE POWER↗
DOE OSTI2023

Bringing 2D Eclipse Mapping out of the Shadows with Leave-one-out Cross Validation

Abstract Eclipse mapping is a technique for inferring 2D brightness maps of transiting exoplanets from the shape of an eclipse light curve. With JWST’s unmatched precision, eclipse mapping is now possible for a large number of exoplanets. However, eclipse mapping has only been applied to two planets, and the nuances of fitting eclipse maps are not yet fully understood. Here, we use Leave-one-out Cross Validation (LOO-CV) to investigate eclipse mapping, with application to a JWST NIRISS/SOSS observation of the ultrahot Jupiter WASP-18b. LOO-CV is a technique that provides insight into the out-of-sample predictive power of models on a data-point-by-data-point basis. We show that constraints on planetary brightness patterns behave as expected, with large-scale variations driven by the phase-curve variation in the light curve and smaller-scale structures constrained by the eclipse ingress and egress. For WASP-18b we show that the need for higher model complexity (smaller-scale features) is driven exclusively by the shape of the eclipse ingress and egress. We use LOO-CV to investigate the relationship between planetary brightness map components when mapping under a positive-flux constraint to better understand the need for complex models. Finally, we use LOO-CV to understand the degeneracy between the competing “hot spot” and “plateau” brightness map models of WASP-18b, showing that the plateau model is driven by the ingress shape and the hot spot model is driven by the egress shape, but preference for neither model is due to outliers or unmodeled signals. Based on this analysis, we make recommendations for the use of LOO-CV in future eclipse-mapping studies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Kepler-1661 b: A Neptune-sized Kepler Transiting Circumbinary Planet around a Grazing Eclipsing Binary

We report the discovery of a Neptune-sized (R{sub p}=3.87±0.06R{sub ⊕}) transiting circumbinary planet, Kepler-1661 b, found in the Kepler photometry. The planet has a period of ∼175 days and its orbit precesses with a period of only 35 yr. The precession causes the alignment of the orbital planes to vary, and the planet is in a transiting configuration only ∼7% of the time as seen from Earth. As with several other Kepler circumbinary planets, Kepler-1661 b orbits close to the stability radius, and is near the (hot) edge of the habitable zone. The planet orbits a single-lined, grazing eclipsing binary, containing a 0.84 M{sub ⊙} and 0.26 M{sub ⊙} pair of stars in a mildly eccentric (e = 0.11), 28.2 day orbit. The system is fairly young, with an estimated age of ∼1–3 Gyr, and exhibits significant starspot modulations. The grazing eclipse configuration means the system is very sensitive to changes in the binary inclination, which manifests itself as a change in the eclipse depth. The starspots contaminate the eclipse photometry, but not in the usual way of inducing spurious eclipse timing variations. Rather, the starspots alter the normalization of the light curve, and hence the eclipse depths. This can lead to spurious eclipse depth variations, which are then incorrectly ascribed to binary orbital precession.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Four new deeply eclipsing white dwarfs in Zwicky Transient Facility

ABSTRACT We present the results of a search for deeply eclipsing white dwarfs in the Zwicky Transient Facility (ZTF) Data Release 4 (DR4). We identify nine deeply eclipsing white dwarf candidates, four of which we followed up with high-cadence photometry and spectroscopy. Three of these systems show total eclipses in the ZTF data and our follow-up Apache Point Observatory 3.5 m telescope observations. Even though the eclipse duration is consistent with sub-stellar companions, our analysis shows that all four systems contain a white dwarf with low-mass stellar companions of ∼0.1 M⊙. We provide mass and radius constraints for both stars in each system based on our photometric and spectroscopic fitting. Finally, we present a list of 41 additional eclipsing WD+M candidates identified in a preliminary search of ZTF DR7, including 12 previously studied systems. We identify two new candidate short-period, eclipsing, white dwarf–brown dwarf binaries within our sample of 41 WD+M candidates based on Pan-STARRS colours.

Kosakowski, A. (ORCID:0000000298781647)↗
DOE OSTI2020

An Asymmetric Eclipse Seen toward the Pre-main-sequence Binary System V928 Tau

K2 observations of the weak-lined T Tauri binary V928 Tau A and B show the detection of a single, asymmetric eclipse, which may be due to a previously unknown substellar companion eclipsing one component of the binary with an orbital period >66 days. Over an interval of about 9 hr, one component of the binary dims by around 60%, returning to its normal brightness about 5 hr later. From modeling of the eclipse shape, we find evidence that the eclipsing companion may be surrounded by a disk or a vast ring system. The modeled disk has a radius of 0.9923 ± 0.0005 R∗, with an inclination of 56.°78 ± 0.°03, a tilt of 41.°22 ± 0.°05, an impact parameter of -0.2506 ± 0.0002 R∗, and an opacity of 1.00. The occulting disk must also move at a transverse velocity of 6.637 ± 0.002 R∗ day -1 , which, depending on whether it orbits V928 Tau A or B, corresponds to approximately 73.53 or 69.26 km s -1 . A search in ground-based archival data reveals additional dimming events, some of which suggest periodicity, but no unambiguous period associated with the eclipse observed by K2. We present a new epoch of astrometry that is used to further refine the orbit of the binary, presenting a new lower bound of 67 yr, and constraints on the possible orbital periods of the eclipsing companion. The binary is also separated by 18' (~2250 au) from the lower-mass CFHT-BD-Tau 7, which is likely associated with V928 Tau A and B. We also present new high-dispersion optical spectroscopy that we use to characterize the unresolved stellar binary.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

TIC 168789840: A Sextuply Eclipsing Sextuple Star System

We report the discovery of a sextuply eclipsing sextuple star system from TESS data, TIC 168789840, also known as TYC 7037-89-1, the first known sextuple system consisting of three eclipsing binaries. The target was observed in Sectors 4 and 5 during Cycle 1, with lightcurves extracted from TESS Full Frame Image data. It was also previously observed by the WASP survey and ASAS-SN. The system consists of three gravitationally bound eclipsing binaries in a hierarchical structure of an inner quadruple system with an outer binary subsystem. Follow-up observations from several different observatories were conducted as a means of determining additional parameters. The system was resolved by speckle interferometry with a 0.″42 separation between the inner quadruple and outer binary, inferring an estimated outer period of ∼2 kyr. It was determined that the fainter of the two resolved components is an 8.217 day eclipsing binary, which orbits the inner quadruple that contains two eclipsing binaries with periods of 1.570 days and 1.306 days. Markov Chain Monte Carlo (MCMC) analysis of the stellar parameters has shown that the three binaries of TIC 168789840 are “triplets,” as each binary is quite similar to the others in terms of mass, radius, and T {sub eff}. As a consequence of its rare composition, structure, and orientation, this object can provide important new insight into the formation, dynamics, and evolution of multiple star systems. Future observations could reveal if the intermediate and outer orbital planes are all aligned with the planes of the three inner eclipsing binaries.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Neutron star mass estimates from gamma-ray eclipses in spider millisecond pulsar binaries

Reliable neutron star mass measurements are key to determining the equation of state of cold nuclear matter, but such measurements are rare. Black widows and redbacks are compact binaries consisting of millisecond pulsars and semi-degenerate companion stars. Spectroscopy of the optically bright companions can determine their radial velocities, providing inclination-dependent pulsar mass estimates. Although inclinations can be inferred from subtle features in optical light curves, such estimates may be systematically biased due to incomplete heating models and poorly understood variability. Using data from the Fermi Large Area Telescope, we have searched for gamma-ray eclipses from 49 spider systems, discovering significant eclipses in 7 systems, including the prototypical black widow PSR B1957+20. Gamma-ray eclipses require direct occultation of the pulsar by the companion, and so the detection, or significant exclusion, of a gamma-ray eclipse strictly limits the binary inclination angle, providing new robust, model-independent pulsar mass constraints. For PSR B1957+20, the eclipse implies a much lighter pulsar (1.81 ± 0.07 solar masses) than inferred from optical light curve modelling.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

β Cephei Pulsations in the High-mass Eclipsing System CW Cephei

CW Cep is an early B-type eclipsing binary with mass measurement precisions better than 1%. We report the discovery of pulsation signatures in the Transiting Exoplanet Survey Satellite time-series data of the system observed during Sectors 17 and 18. Our binary modeling indicates that the target star is a partially eclipsing detached system with masses of 12.95 M {sub ⊙} and 11.88 M {sub ⊙} and radii of 5.52 R {sub ⊙} and 5.09 R {sub ⊙} in an eccentric orbit of e = 0.0305. The distance to the eclipsing system, 928 ± 36 pc, is much more precise than the Gaia distance of 962 ± 453 pc. Applying multifrequency analyses to the residual light curve in the outside-eclipse part, we detected 13 significant signals in two frequency regions. Six frequencies below 1 day{sup −1} appeared to be mostly orbital harmonic and combination terms, or sidelobes due to insufficient removal of the binary effects. In contrast, seven frequencies clustered around 2.73 day{sup −1} and 5.34 day{sup −1} could be considered β Cep–type pulsations. Our results represent the second discovery of β Cep pulsations present in double-lined eclipsing binaries with precise masses and, hence, CW Cep serves as an important test bed for the asteroseismic modeling of high-mass stars.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Tidally Excited Modes and δ Scuti Pulsations in the Eclipsing Triple Star IM Persei

IM Per is a triple star system whose eclipsing pair masses and radii are accurate to within 1%. The Transiting Exoplanet Survey Satellite (TESS) light curve of the program target exhibits partial eclipses and multiple oscillations with millimagnitude-level amplitudes. It is found that the oscillations affect eclipse timing measurements. Binary modeling of the high-quality TESS data indicates that the eclipsing components of the triple system are twin dwarfs with parameters of M {sub 2}/M {sub 1} = 0.995, R {sub 2}/R {sub 1} = 0.901, and Δ(T{sub eff,1}–T{sub eff,2}) = 12 K in an eccentric (e = 0.049), detached configuration. The third light of l {sub 3} = 0.054 may mostly come from a G-type tertiary companion. Our predicted parallax of 1.52 ± 0.09 mas is concurrent with the Gaia measurement of 1.52 ± 0.05 mas. Multifrequency analysis of the outside-eclipse residuals reveals 22 significant pulsation signals: 4 in the gravity-mode region (0.03−2.22 day{sup −1}) and 18 in the pressure-mode region (9.19−25.12 day{sup −1}). Of the low frequencies, f {sub 11} and f {sub 14} are orbital harmonics that can be identified as tidally excited modes. The pulsation periods and constants for the high frequencies, and the position in the Cepheid instability strip demonstrate that the pulsating component of IM Per is a δ Sct variable.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Discovery and characterization of five new eclipsing AM CVn systems

ABSTRACT AM CVn systems are ultra-compact, hydrogen-depleted, and helium-rich, accreting binaries with degenerate or semidegenerate donors. We report the discovery of five new eclipsing AM CVn systems with orbital periods of 61.5, 55.5, 53.3, 37.4, and 35.4 min. These systems were discovered by searching for deep eclipses in the Zwicky Transient Facility (ZTF) light curves of white dwarfs selected using Gaia parallaxes. We obtained phase-resolved spectroscopy to confirm that all systems are AM CVn binaries, and we obtained high-speed photometry to confirm the eclipse and characterize the systems. The spectra show double-peaked H e lines but also show metals, including K and Zn, elements that have never been detected in AM CVn systems before. By modelling the high-speed photometry, we measured the mass and radius of the donor star, potentially constraining the evolutionary channel that formed these AM CVn systems. We determined that the average mass of the accreting white dwarf is ≈0.8 M⊙, and that the white dwarfs in long-period systems are hotter than predicted by recently updated theoretical models. The donors have a high entropy and are a factor of ≈2 more massive compared to zero-entropy donors at the same orbital period. The large donor radius is most consistent with H e-star progenitors, although the observed spectral features seem to contradict this. The discovery of five new eclipsing AM CVn systems is consistent with the known observed AM CVn space density and estimated ZTF recovery efficiency.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Fundamental effective temperature measurements for eclipsing binary stars – IV. Selection of new benchmark stars and first results for HD 22064

I describe the selection and initial characterization of 20 eclipsing binary stars that are suitable for calibration and testing of stellar models and data analysis algorithms used by the PLATO mission and spectroscopic surveys. The binary stars selected are F-/G-type dwarf stars with M-type dwarf companions that contribute less than 2 per cent of the flux at optical wavelengths. The light curves typically show well-defined total eclipses with very little variability between the eclipses. I have used near-infrared spectra obtained by the APOGEE survey to measure the spectroscopic orbit for both stars in HD 22064. Combined with an analysis of the TESS light curve, I derive the following masses and radii: M 1 = 1.35 ± 0.03M ⊙ , M 2 = 0.58 ± 0.01M ⊙ , R 1 = 1.554 ± 0.014R ⊙ , R 2 = 0.595 ± 0.008R ⊙ . Using R 1 and the parallax from Gaia EDR3, I find that the primary star’s angular diameter is θ = 0.1035 ± 0.0009 mas. The apparent bolometric flux of the primary star is ${\mathcal {F}}_{{\oplus },0} = (7.51\pm 0.09)\times 10^{-9}$ erg cm -2 s -1 . Hence, this F2V star has an effective temperature $T_{\rm eff,1} = 6763{\rm \, K} \pm 39{\rm \, K}$. HD 22064 is an ideal benchmark star that can be used for ‘end-to-end’ tests of the stellar parameters measured by large-scale spectroscopic surveys or stellar parameters derived from asteroseismology with PLATO. The techniques described here for HD 22064 can be applied to the other eclipsing binaries in the sample in order to create an all-sky network of such benchmark stars.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Trends in Spitzer Secondary Eclipses

It is well established that the magnitude of the incident stellar flux is the single most important factor in determining the day–night temperature gradients and atmospheric chemistries of short-period gas giant planets. However, it is likely that other factors, such as planet-to-planet variations in atmospheric metallicity, C/O ratio, and cloud properties, also contribute to the observed diversity of infrared spectra for this population of planets. In this study, we present new 3.6 and 4.5 μm secondary eclipse measurements for five transiting gas giant planets: HAT-P-5b, HAT-P-38b, WASP-7b, WASP-72b, and WASP-127b. We detect eclipses in at least one bandpass for all five planets and confirm circular orbits for all planets except WASP-7b, which shows evidence for a nonzero eccentricity. Building on the work of Garhart et al., we place these new planets into a broader context by comparing them with the sample of all planets with measured Spitzer secondary eclipses. We find that incident flux is the single most important factor for determining the atmospheric chemistry and circulation patterns of short-period gas giant planets. Although we might also expect surface gravity and host star metallicity to play a secondary role, we find no evidence for correlations with either of these two variables.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

The Hubble PanCET Program: Transit and Eclipse Spectroscopy of the Strongly Irradiated Giant Exoplanet WASP-76b

Ultra-hot Jupiters with equilibrium temperatures greater than 2000 K are uniquely interesting targets as they provide us crucial insights into how atmospheres behave under extreme conditions. This class of giant planets receives intense radiation from their host star and usually has strongly irradiated and highly inflated atmospheres. At such a high temperature, cloud formation is expected to be suppressed and thermal dissociation of water vapor could occur. We observed the ultra-hot Jupiter WASP-76b with seven transits and five eclipses using the Hubble Space Telescope and the Spitzer Space Telescope (Spitzer) for a comprehensive study of its atmospheric chemical and physical processes. We detected TiO and H{sub 2}O absorption in the optical and near-infrared transit spectrum. Additional absorption by a number of neutral and ionized heavy metals like Fe, Ni, Ti, and SiO help explain the short-wavelength transit spectrum. The secondary eclipse spectrum shows muted water feature but a strong CO emission feature in Spitzer’s 4.5 μm band indicating an inverted temperature pressure profile. We analyzed both the transit and eclipse spectra with a combination of self-consistent PHOENIX models and atmospheric retrieval. Both spectra were well fitted by the self-consistent PHOENIX forward atmosphere model in chemical and radiative equilibrium at solar metallicity, adding to the growing evidence that both TiO/VO and NUV heavy metals opacity are prominent NUV-optical opacity sources in the stratospheres of ultra-hot Jupiters.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

High resolution X-ray spectroscopy of Supergiant HMXB 4U1700-37 during the compact object eclipse.

In this work, we present an analysis of the first observation of the iconic High Mass X-ray Binary 4U 1700-37 with the Chandra High Energy Transmission Gratings during an X-ray eclipse. The goal of the observation was to study the structure/physical conditions in the clumpy stellar wind through high resolution spectroscopy. We find that: a) emission line brightness from K shell transitions, corresponding to near neutral species, directly correlates with continuum illumination. However, these lines do not greatly diminish during eclipse. This is readily explained if fluorescence Kα emission comes from the bulk of the wind. b) The highly ionised Fe xxv and Fe xxvi Lyα diminish during eclipse. Thus, they must be produced in the vicinity of the compact object where log ξ > 3. c) to describe the emission line spectrum, the sum of two self consistent photo ionisation models with low ionisation (log ξ ~ -1) and high ionisation (log ξ ~2.4) is required. From their emission measures, the clump-to-interclump density ratio can be estimated to be nc/ni ~ 300. To fit the complex He-like Si xiii profile, the plasma requires a broadening with vbulk ~ 840 km s-1. Reproducing the observed r ≈ f line fluxes requires the addition of a third collisionally ionised plasma. d) Emission lines widths appear unresolved at the hetg gratings resolution with exception of Silicon. There is no clear radial segregation between (quasi)neutral and ionised species, consistent with cold wind clumps interspersed in a hot rarefied interclump medium.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

WD1032 + 011, an inflated brown dwarf in an old eclipsing binary with a white dwarf

We present the discovery of only the third brown dwarf known to eclipse a non-accreting white dwarf. Gaia parallax information and multicolour photometry confirm that the white dwarf is cool (9950 ± 150 K) and has a low mass (0.45 ± 0.05 M ⊙ ), and spectra and light curves suggest the brown dwarf has a mass of 0.067 ± 0.006 M ⊙ (70M Jup ) and a spectral type of L5 ± 1. The kinematics of the system show that the binary is likely to be a member of the thick disc and therefore at least 5-Gyr old. In conclusion, the high-cadence light curves show that the brown dwarf is inflated, making it the first brown dwarf in an eclipsing white dwarf-brown dwarf binary to be so.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Statistical Characterization of Hot Jupiter Atmospheres Using Spitzer’s Secondary Eclipses

We report 78 secondary eclipse depths for a sample of 36 transiting hot Jupiters observed at 3.6 and 4.5 μm using the Spitzer Space Telescope. Our eclipse results for 27 of these planets are new, and include highly irradiated worlds such as KELT-7b, WASP-87b, WASP-76b, and WASP-64b, and important targets for James Webb Space Telescope such as WASP-62b. We find that WASP-62b has a slightly eccentric orbit (ecos ω=0.00614±0.00064), and we confirm the eccentricity of HAT-P-13b and WASP-14b. The remainder are individually consistent with circular orbits, but we find statistical evidence for eccentricity increasing with orbital period in our range from 1 to 5 days. Our day-side brightness temperatures for the planets yield information on albedo and heat redistribution, following Cowan & Agol (2011). Planets having maximum day-side temperatures exceeding ~2200 K are consistent with having zero albedo and a distribution of stellar irradiance uniformly over the day-side hemisphere. Our most intriguing result is that we detect a systematic difference between the emergent spectra of these hot Jupiters as compared to blackbodies. The ratio of observed brightness temperatures, Tb(4.5)/Tb(3.6), increases with equilibrium temperature by 100 ± 24 parts-per-million per Kelvin, over the entire temperature range in our sample (800–2500 K). No existing model predicts this trend over such a large range of temperature. We suggest that this may be due to a structural difference in the atmospheric temperature profiles of real planetary atmospheres as compared to models.

79 ASTRONOMY AND ASTROPHYSICS↗