To constrain the formation history of an exoplanet, we need to know its chemical composition
. With an equilibrium temperature of about 4,050 kelvin
, the exoplanet KELT-9b (also known as HD 195689b) ...is an archetype of the class of ultrahot Jupiters that straddle the transition between stars and gas-giant exoplanets and are therefore useful for studying atmospheric chemistry. At these high temperatures, iron and several other transition metals are not sequestered in molecules or cloud particles and exist solely in their atomic forms
. However, despite being the most abundant transition metal in nature, iron has not hitherto been detected directly in an exoplanet because it is highly refractory. The high temperatures of KELT-9b imply that its atmosphere is a tightly constrained chemical system that is expected to be nearly in chemical equilibrium
and cloud-free
, and it has been predicted that spectral lines of iron should be detectable in the visible range of wavelengths
. Here we report observations of neutral and singly ionized atomic iron (Fe and Fe
) and singly ionized atomic titanium (Ti
) in the atmosphere of KELT-9b. We identify these species using cross-correlation analysis
of high-resolution spectra obtained as the exoplanet passed in front of its host star. Similar detections of metals in other ultrahot Jupiters will provide constraints for planetary formation theories.
Abstract
We present high-resolution dayside thermal emission observations of the exoplanet WASP-18 b using IGRINS on Gemini South. We remove stellar and telluric signatures using standard algorithms, ...and we extract the planet signal via cross-correlation with model spectra. We detect the atmosphere of WASP-18 b at a signal-to-noise ratio (S/N) of 5.9 using a full chemistry model, measure H
2
O (S/N = 3.3), CO (S/N = 4.0), and OH (S/N = 4.8) individually, and confirm previous claims of a thermal inversion layer. The three species are confidently detected (>4
σ
) with a Bayesian inference framework, which we also use to retrieve abundance, temperature, and velocity information. For this ultrahot Jupiter (UHJ), thermal dissociation processes likely play an important role. Retrieving abundances constant with altitude and allowing the temperature–pressure profile to adjust freely results in a moderately super-stellar carbon-to-oxygen ratio (C/O =
0.75
−
0.17
+
0.14
) and metallicity (M/H =
1.03
−
1.01
+
0.65
). Accounting for undetectable oxygen produced by thermal dissociation leads to C/O =
0.45
−
0.10
+
0.08
and M/H =
1.17
−
1.01
+
0.66
. A retrieval that assumes radiative–convective–thermochemical equilibrium and naturally accounts for thermal dissociation constrains C/O < 0.34 (2
σ
) and M/H =
0.48
−
0.29
+
0.33
, in line with the chemistry of the parent star. Looking at the velocity information, we see a tantalizing signature of different Doppler shifts at the level of a few kilometers per second for different molecules, which might probe dynamics as a function of altitude and/or location on the planet disk. Our results demonstrate that ground-based, high-resolution spectroscopy at infrared wavelengths can provide meaningful constraints on the compositions and climate of highly irradiated planets. This work also elucidates potential pitfalls with commonly employed retrieval assumptions when applied to the spectra of UHJs.
Abstract
We present high-resolution dayside thermal emission observations of the exoplanet KELT-20b/MASCARA-2b using the MAROON-X spectrograph. Applying the cross-correlation method with both ...empirical and theoretical masks and a retrieval analysis, we confirm previous detections of Fe
i
emission lines and we detect Ni
i
for the first time in the planet (at 4.7
σ
confidence). We do not see evidence for additional species in the MAROON-X data, including notably predicted thermal inversion agents TiO and VO, their atomic constituents Ti
i
and V
i
, and previously claimed species Fe
ii
and Cr
i
. We also perform a joint retrieval with existing Hubble Space Telescope/WFC3 spectroscopy and Spitzer/IRAC photometry. This allows us to place bounded constraints on the abundances of Fe
i
, H
2
O, and CO, and to place a stringent upper limit on the TiO abundance. The results are consistent with KELT-20b having a solar to slightly supersolar composition atmosphere in terms of the bulk metal enrichment, and the carbon-to-oxygen and iron-to-oxygen ratios. However, the TiO volume mixing ratio upper limit (10
−7.6
at 99% confidence) is inconsistent with this picture, which, along with the nondetection of Ti
i
, points to sequestration of Ti species, possibly due to nightside condensation. The lack of TiO but the presence of a large H
2
O emission feature in the WFC3 data is challenging to reconcile within the context of 1D self-consistent, radiative-convective models.
Abstract Ground-based high-resolution and space-based low-resolution spectroscopy are the two main avenues through which transiting exoplanet atmospheres are studied. Both methods provide unique ...strengths and shortcomings, and combining the two can be a powerful probe into an exoplanet’s atmosphere. Within a joint atmospheric retrieval framework, we combined JWST NIRSpec/G395H secondary eclipse spectra and Gemini South/IGRINS pre- and post-eclipse thermal emission observations of the hot Jupiter WASP-77A b. Our inferences from the IGRINS and NIRSpec data sets are consistent with each other, and combining the two allows us to measure the gas abundances of H 2 O and CO, as well as the vertical thermal structure, with higher precision than either data set provided individually. We confirm WASP-77A b’s subsolar metallicity ((C+O)/H = −0.61 − 0.09 + 0.10 ) and solar C/O ratio (C/O = 0.57 − 0.06 + 0.06 ) . The two types of data are complementary, and our abundance inferences are mostly driven by the IGRINS data, while inference of the thermal structure is driven by the NIRSpec data. Our ability to draw inferences from the post-eclipse IGRINS data is highly sensitive to the number of singular values removed in the detrending process, potentially due to high and variable humidity. We also search for signatures for atmospheric dynamics in the IGRINS data and find that propagated ephemeris error can manifest as either an orbital eccentricity or a strong equatorial jet. Neither are detected when using more up-to-date ephemerides. However, we find moderate evidence of thermal inhomogeneity and measure a cooler nightside that presents itself in the later phases after secondary eclipse.
Abstract
Close-in lava planets represent an extreme example of terrestrial worlds, but their high temperatures may allow us to probe a diversity of crustal compositions. The brightest and most ...well-studied of these objects is 55 Cancri e, a nearby super-Earth with a remarkably short 17 hr orbit. However, despite numerous studies, debate remains about the existence and composition of its atmosphere. We present upper limits on the atmospheric pressure of 55 Cnc e derived from high-resolution time-series spectra taken with Gemini-N/MAROON-X. Our results are consistent with current crustal evaporation models for this planet which predict a thin ∼100 mbar atmosphere. We conclude that, if a mineral atmosphere is present on 55 Cnc e, the atmospheric pressure is below 100 mbar.
Space-borne low- to medium-resolution (ℛ ~ 102–103) and ground-based high-resolution spectrographs (ℛ ~ 105) are commonly used to obtain optical and near infrared transmission spectra of exoplanetary ...atmospheres. In this wavelength range, space-borne observations detect the broadest spectral features (alkali doublets, molecular bands, scattering, etc.), while high-resolution, ground-based observations probe the sharpest features (cores of the alkali lines, molecular lines). The two techniques differ by several aspects. (1) The line spread function of ground-based observations is ~103 times narrower than for space-borne observations; (2) Space-borne transmission spectra probe up to the base of thermosphere (P ≳ 10−6 bar), while ground-based observations can reach lower pressures (down to ~10−11 bar) thanks to their high resolution; (3) Space-borne observations directly yield the transit depth of the planet, while ground-based observations can only measure differences in the apparent size of the planet at different wavelengths. These differences make it challenging to combine both techniques. Here, we develop a robust method to compare theoretical models with observations at different resolutions. We introduce πη, a line-by-line 1D radiative transfer code to compute theoretical transmission spectra over a broad wavelength range at very high resolution (ℛ ~ 106, or Δλ ~ 0.01 Å). An hybrid forward modeling/retrieval optimization scheme is devised to deal with the large computational resources required by modeling a broad wavelength range ~0.3–2 μm at high resolution. We apply our technique to HD 189733b. In this planet, HST observations reveal a flattened spectrum due to scattering by aerosols, while high-resolution ground-based HARPS observations reveal sharp features corresponding to the cores of sodium lines. We reconcile these apparent contrasting results by building models that reproduce simultaneously both data sets, from the troposphere to the thermosphere. We confirm: (1) the presence of scattering by tropospheric aerosols; (2) that the sodium core feature is of thermospheric origin. When we take into account the presence of aerosols, the large contrast of the core of the sodium lines measured by HARPS indicates a temperature of up to ~10 000K in the thermosphere, higher than what reported in the literature. We also show that the precise value of the thermospheric temperature is degenerate with the relative optical depth of sodium, controlled by its abundance, and of the aerosol deck.
Anderson-Fabry disease (AFD), a genetic disorder caused by mutations in the α-galactosidase-A (GLA) gene, disrupts lysosomal function, leading to vascular complications. The accumulation of ...globotriaosylceramide (Gb3) in arterial walls triggers upregulation of adhesion molecules, decreases endothelial nitric oxide synthesis, and induces reactive oxygen species production. This cascade results in fibrotic thickening, endothelial dysfunction, hypercontractility, vasospasm, and a pro-thrombotic phenotype. AFD patients display increased intima-media thickness (IMT) and reduced flow-mediated dilation (FMD), indicating heightened cardiovascular risk. Nailfold capillaroscopy (NFC) shows promise in diagnosing and monitoring microcirculatory disorders in AFD, though it remains underexplored. Morphological evidence of AFD as a storage disorder can be demonstrated through electron microscopy and immunodetection of Gb3. Secondary pathophysiological disturbances at cellular, tissue, and organ levels contribute to the clinical manifestations, with prominent lysosomal inclusions observed in vascular, cardiac, renal, and neuronal cells. Chronic accumulation of Gb3 represents a state of ongoing toxicity, leading to increased cell turnover, particularly in vascular endothelial cells. AFD-related vascular pathology includes increased renin-angiotensin system activation, endothelial dysfunction, and smooth muscle cell proliferation, resulting in IMT increase. Furthermore, microvascular alterations, such as atypical capillaries observed through NFC, suggest early microvascular involvement. This review aims to unravel the complex interplay between inflammation, oxidative stress, and endothelial dysfunction in AFD, highlighting the potential connections between metabolic disturbances, oxidative stress, inflammation, and fibrosis in vascular and cardiac complications. By exploring novel cardiovascular risk factors and potential diagnostic tools, we can advance our understanding of these mechanisms, which extend beyond sphingolipid accumulation to include other significant contributors to disease pathogenesis. This comprehensive approach can pave the way for innovative therapeutic strategies and improved patient outcomes.
Space-borne low- to medium-resolution (ℛ ~ 10
2
–10
3
) and ground-based high-resolution spectrographs (ℛ ~ 10
5
) are commonly used to obtain optical and near infrared transmission spectra of ...exoplanetary atmospheres. In this wavelength range, space-borne observations detect the broadest spectral features (alkali doublets, molecular bands, scattering, etc.), while high-resolution, ground-based observations probe the sharpest features (cores of the alkali lines, molecular lines). The two techniques differ by several aspects. (1) The line spread function of ground-based observations is ~10
3
times narrower than for space-borne observations; (2) Space-borne transmission spectra probe up to the base of thermosphere (
P
≳ 10
−6
bar), while ground-based observations can reach lower pressures (down to ~10
−11
bar) thanks to their high resolution; (3) Space-borne observations directly yield the transit depth of the planet, while ground-based observations can only measure differences in the apparent size of the planet at different wavelengths. These differences make it challenging to combine both techniques. Here, we develop a robust method to compare theoretical models with observations at different resolutions. We introduce
π
η
, a line-by-line 1D radiative transfer code to compute theoretical transmission spectra over a broad wavelength range at very high resolution (ℛ ~ 10
6
, or Δ
λ
~ 0.01 Å). An hybrid forward modeling/retrieval optimization scheme is devised to deal with the large computational resources required by modeling a broad wavelength range ~0.3–2
μ
m at high resolution. We apply our technique to HD 189733b. In this planet, HST observations reveal a flattened spectrum due to scattering by aerosols, while high-resolution ground-based HARPS observations reveal sharp features corresponding to the cores of sodium lines. We reconcile these apparent contrasting results by building models that reproduce simultaneously both data sets, from the troposphere to the thermosphere. We confirm: (1) the presence of scattering by tropospheric aerosols; (2) that the sodium core feature is of thermospheric origin. When we take into account the presence of aerosols, the large contrast of the core of the sodium lines measured by HARPS indicates a temperature of up to ~10 000K in the thermosphere, higher than what reported in the literature. We also show that the precise value of the thermospheric temperature is degenerate with the relative optical depth of sodium, controlled by its abundance, and of the aerosol deck.
Transmission spectroscopy with ground-based, high-resolution instruments provides key insight into the composition of exoplanetary atmospheres. Molecules such as water and carbon monoxide have been ...unambiguously identified in hot gas giants through cross-correlation techniques. A maximum in the cross-correlation function (CCF) is found when the molecular absorption lines in a binary mask or model template match those contained in the planet. Here, we demonstrate how the CCF method can be used to diagnose broadband spectroscopic features such as scattering by aerosols in high-resolution transit spectra. The idea consists in exploiting the presence of multiple water bands from the optical to the near-infrared. We have produced a set of models of a typical hot Jupiter spanning various conditions of temperature and aerosol coverage. We demonstrate that comparing the CCFs of individual water bands for the models constrains the presence and the properties of the aerosol layers. The contrast difference between the CCFs of two bands can reach ~100 ppm, which could be readily detectable with current or upcoming high-resolution stabilized spectrographs spanning a wide spectral range, such as ESPRESSO, CARMENES, HARPS-N+GIANO, HARPS+NIRPS, SPIRou, or CRIRES+.
The abundance of refractory elements in giant planets can provide key insights into their formation histories
. Owing to the low temperatures of the Solar System giants, refractory elements condense ...below the cloud deck, limiting sensing capabilities to only highly volatile elements
. Recently, ultra-hot giant exoplanets have allowed for some refractory elements to be measured, showing abundances broadly consistent with the solar nebula with titanium probably condensed out of the photosphere
. Here we report precise abundance constraints of 14 major refractory elements on the ultra-hot giant planet WASP-76b that show distinct deviations from proto-solar and a sharp onset in condensation temperature. In particular, we find nickel to be enriched, a possible sign of the accretion of the core of a differentiated object during the evolution of the planet. Elements with condensation temperatures below 1,550 K otherwise closely match those of the Sun
before sharply transitioning to being strongly depleted above 1,550 K, which is well explained by nightside cold-trapping. We further unambiguously detect vanadium oxide on WASP-76b, a molecule long suggested to drive atmospheric thermal inversions
, and also observe a global east-west asymmetry
in its absorption signals. Overall, our findings indicate that giant planets have a mostly stellar-like refractory elemental content and suggest that temperature sequences of hot Jupiter spectra can show abrupt transitions wherein a mineral species is either present or completely absent if a cold trap exists below its condensation temperature
.
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