In the pebble accretion scenario, the pebbles that form planets drift inward from the outer disk regions, carrying water ice with them. At the water ice line, the water ice on the inward drifting ...pebbles evaporates and is released into the gas phase, resulting in water-rich gas and dry pebbles that move into the inner disk regions. Large planetary cores can block the inward drifting pebbles by forming a pressure bump outside their orbit in the protoplanetary disk. Depending on the relative position of a growing planetary core relative to the water ice line, water-rich pebbles might be blocked outside or inside the water ice line. Pebbles blocked outside the water ice line do not evaporate and thus do not release their water vapor into the gas phase, resulting in a dry inner disk, while pebbles blocked inside the water ice line release their water vapor into the gas phase, resulting in water vapor diffusing into the inner disk. As a consequence, close-in sub-Neptunes that accrete some gas from the disk should be dry or wet, respectively, if outer gas giants are outside or inside the water ice line, assuming that giant planets form fast, as has been suggested for Jupiter in our Solar System. Alternatively, a sub-Neptune could form outside the water ice line, accreting a large amount of icy pebbles and then migrating inward as a very wet sub-Neptune. We suggest that the water content of inner sub-Neptunes in systems with giant planets that can efficiently block the inward drifting pebbles could constrain the formation conditions of these systems, thus making these sub-Neptunes exciting targets for detailed characterization (e.g., with JWST, ELT, or ARIEL). In addition, the search for giant planets in systems with already characterized sub-Neptunes can be used to constrain the formation conditions of giant planets as well.
Abstract
With an equilibrium temperature above 2500 K, the recently discovered HAT-P-70b belongs to a new class of exoplanets known as ultrahot Jupiters: extremely irradiated gas giants with day-side ...temperatures that resemble those found in stars. These ultrahot Jupiters are among the most amenable targets for follow-up atmospheric characterization through transmission spectroscopy. Here, we present the first analysis of the transmission spectrum of HAT-P-70b using high-resolution data from the HARPS-N spectrograph of a single-transit event. We use a cross-correlation analysis and transmission spectroscopy to look for atomic and molecular species in the planetary atmosphere. We detect absorption by Ca
ii
, Cr
i
, Cr
ii
, Fe
i
, Fe
ii
, H
i
, Mg
i
, Na
i,
and V
i
, and we find tentative evidence of Ca
i
and Ti
ii
. Overall, these signals appear blueshifted by a few km s
−1
, suggestive of winds flowing at high velocity from the day side to the night side. We individually resolve the Ca
ii
H and K lines, the Na
i
doublet, and the H
α
, H
β
, and H
γ
Balmer lines. The cores of the Ca
ii
and H
i
lines form well above the continuum, indicating the existence of an extended envelope. We refine the obliquity of this highly misaligned planet to
107.9
−
1.7
+
2.0
degrees by examining the Doppler shadow that the planet casts on its A-type host star. These results place HAT-P-70b as one of the exoplanets with the highest number of species detected in its atmosphere.
Abstract
Extremely low-density exoplanets are tantalizing targets for atmospheric characterization because of their promisingly large signals in transmission spectroscopy. We present the first ...analysis of the atmosphere of the lowest-density gas giant currently known, HAT-P-67b. This inflated Saturn-mass exoplanet sits at the boundary between hot and ultrahot gas giants, where thermal dissociation of molecules begins to dominate atmospheric composition. We observed a transit of HAT-P-67b at high spectral resolution with CARMENES and searched for atomic and molecular species using cross-correlation and likelihood mapping. Furthermore, we explored potential atmospheric escape by targeting H
α
and the metastable helium line. We detect Ca
ii
and Na
i
with significances of 13.2
σ
and 4.6
σ
, respectively. Unlike in several ultrahot Jupiters, we do not measure a day-to-night wind. The large line depths of Ca
ii
suggest that the upper atmosphere may be more ionized than models predict. We detect strong variability in H
α
and the helium triplet during the observations. These signals suggest the possible presence of an extended planetary outflow that causes an early ingress and late egress. In the averaged transmission spectrum, we measure redshifted absorption at the ∼3.8% and ∼4.5% level in the H
α
and He
i
triplet lines, respectively. From an isothermal Parker wind model, we derive a mass-loss rate of
M
̇
∼
10
13
g
s
−
1
and an outflow temperature of
T
∼ 9900 K. However, due to the lack of a longer out-of-transit baseline in our data, additional observations are needed to rule out stellar variability as the source of the H
α
and He signals.
Abstract
We present a new optical transmission spectrum of the hot Jupiter WASP-79b. We observed three transits with the STIS instrument mounted on the Hubble Space Telescope (HST), spanning 0.3–1.0
...μ
m. Combining these transits with previous observations, we construct a complete 0.3–5.0
μ
m transmission spectrum of WASP-79b. Both HST and ground-based observations show decreasing transit depths toward blue wavelengths, contrary to expectations from Rayleigh scattering or hazes. We infer atmospheric and stellar properties from the full near-UV to infrared transmission spectrum of WASP-79b using three independent retrieval codes, all of which yield consistent results. Our retrievals confirm previous detections of H
2
O (at 4.0
σ
confidence) while providing moderate evidence of H
−
bound–free opacity (3.3
σ
) and strong evidence of stellar contamination from unocculted faculae (4.7
σ
). The retrieved H
2
O abundance (∼1%) suggests a superstellar atmospheric metallicity, though stellar or substellar abundances remain consistent with present observations (O/H = 0.3–34× stellar). All three retrieval codes obtain a precise H
−
abundance constraint: log(
X
H
−
) ≈ −8.0 ± 0.7. The potential presence of H
−
suggests that James Webb Space Telescope observations may be sensitive to ionic chemistry in the atmosphere of WASP-79b. The inferred faculae are ∼500 K hotter than the stellar photosphere, covering ∼15% of the stellar surface. Our analysis underscores the importance of observing UV–optical transmission spectra in order to disentangle the influence of unocculted stellar heterogeneities from planetary transmission spectra.
Abstract
As part of the Panchromatic Exoplanet Treasury program, we have conducted a spectroscopic study of WASP-79b, an inflated hot Jupiter orbiting an F-type star in Eridanus with a period of 3.66 ...days. Building on the original WASP and TRAPPIST photometry of Smalley et al., we examine
Hubble Space Telescope
(
HST
)/Wide Field Camera 3 (WFC3) (1.125–1.650
μ
m), Magellan/Low Dispersion Survey Spectrograph (LDSS)-3C (0.6–1
μ
m) data, and
Spitzer
data (3.6 and 4.5
μ
m). Using data from all three instruments, we constrain the water abundance to be −2.20 ≤ log(H
2
O) ≤ −1.55. We present these results along with the results of an atmospheric retrieval analysis, which favor inclusion of FeH and H
−
in the atmospheric model. We also provide an updated ephemeris based on the Smalley,
HST
/WFC3, LDSS-3C,
Spitzer
, and
Transiting Exoplanet Survey Satellite
(
TESS
) transit times. With the detectable water feature and its occupation of the clear/cloudy transition region of the temperature/gravity phase space, WASP-79b is a target of interest for the approved
James Webb Space Telescope
(
JWST
) Director’s Discretionary Early Release Science (ERS) program, with ERS observations planned to be the first to execute in Cycle 1. Transiting exoplanets have been approved for 78.1 hr of data collection, and with the delay in the
JWST
launch, WASP-79b is now a target for the Panchromatic Transmission program. This program will observe WASP-79b for 42 hr in four different instrument modes, providing substantially more data by which to investigate this hot Jupiter.
ABSTRACT
We present an optical transmission spectrum of the hot Jupiter WASP-101b. We observed three primary transits with Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph, covering ...a wavelength range from 0.3 to 1 $\mu$m. The observations suffer from significant systematics that we model using Gaussian Processes. Kernel selection for the Gaussian Processes is performed in a data-driven approach through Bayesian model comparison. We find a flat and featureless transmission spectrum, corroborating a previous measurement obtained with HST/Wide-Field Camera 3 in the 1–1.7 $\mu$m range. The spectrum is consistent with high-altitude clouds located at less than 100 $\mu$bar. This cloud layer completely blocks our view into deeper parts of the atmosphere and makes WASP-101b the cloudiest gas giant observed so far. We compute a series of temperature-pressure profiles for WASP-101b and compare these to condensation curves for cloud particles, which match clouds composed of silicates. We also include 13 transits observed with Transiting Exoplanet Survey Satellite and use these to refine system parameters.
Abstract
Exoplanets with cloud-free, haze-free atmospheres at the pressures probed by transmission spectroscopy represent a valuable opportunity for detailed atmospheric characterization and precise ...chemical abundance constraints. We present the first optical to infrared (0.3−5
μ
m) transmission spectrum of the hot Jupiter WASP-62b, measured with Hubble/STIS and Spitzer/IRAC. The spectrum is characterized by a 5.1
σ
detection of Na
i
absorption at 0.59
μ
m, in which the pressure-broadened wings of the Na D-lines are observed from space for the first time. A spectral feature at 0.4
μ
m is tentatively attributed to SiH at 2.1
σ
confidence. Our retrieval analyses are consistent with a cloud-free atmosphere without significant contamination from stellar heterogeneities. We simulate James Webb Space Telescope (JWST) observations, for a combination of instrument modes, to assess the atmospheric characterization potential of WASP-62b. We demonstrate that JWST can conclusively detect Na, H
2
O, FeH, NH
3
, CO, CO
2
, CH
4
, and SiH within the scope of its Early Release Science (ERS) program. As the only transiting giant planet currently known in the JWST Continuous Viewing Zone, WASP-62b could prove a benchmark giant exoplanet for detailed atmospheric characterization in the James Webb era.
As part of the Panchromatic Exoplanet Treasury program, we have conducted a spectroscopic study of WASP-79b, an inflated hot Jupiter orbiting an F-type star in Eridanus with a period of 3.66 days. ...Building on the original WASP and TRAPPIST photometry of Smalley et al., we examine Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) (1.125-1.650 m), Magellan/Low Dispersion Survey Spectrograph (LDSS)-3C (0.6-1 m) data, and Spitzer data (3.6 and 4.5 m). Using data from all three instruments, we constrain the water abundance to be −2.20 ≤ log(H2O) ≤ −1.55. We present these results along with the results of an atmospheric retrieval analysis, which favor inclusion of FeH and H− in the atmospheric model. We also provide an updated ephemeris based on the Smalley, HST/WFC3, LDSS-3C, Spitzer, and Transiting Exoplanet Survey Satellite (TESS) transit times. With the detectable water feature and its occupation of the clear/cloudy transition region of the temperature/gravity phase space, WASP-79b is a target of interest for the approved James Webb Space Telescope (JWST) Director's Discretionary Early Release Science (ERS) program, with ERS observations planned to be the first to execute in Cycle 1. Transiting exoplanets have been approved for 78.1 hr of data collection, and with the delay in the JWST launch, WASP-79b is now a target for the Panchromatic Transmission program. This program will observe WASP-79b for 42 hr in four different instrument modes, providing substantially more data by which to investigate this hot Jupiter.
The absorption of light by molecules in the atmosphere of Earth is a complication for ground-based observations of astrophysical objects. Comprehensive information on various molecular species is ...required to correct for this so called telluric absorption. We present a neural network autoencoder approach for extracting a telluric transmission spectrum from a large set of high-precision observed solar spectra from the HARPS-N radial velocity spectrograph. We accomplish this by reducing the data into a compressed representation, which allows us to unveil the underlying solar spectrum and simultaneously uncover the different modes of variation in the observed spectra relating to the absorption of \(\mathrm{H_2O}\) and \(\mathrm{O_2}\) in the atmosphere of Earth. We demonstrate how the extracted components can be used to remove \(\mathrm{H_2O}\) and \(\mathrm{O_2}\) tellurics in a validation observation with similar accuracy and at less computational expense than a synthetic approach with molecfit.
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