113 research outputs found
New transit timing observations for GJ 436 b, HAT-P-3 b, HAT-P-19 b, WASP-3 b, and XO-2 b
We present new transit observations acquired between 2014 and 2018 for the hot exoplanets GJ 436 b, HAT-P-3 b, HAT-P-19 b, WASP-3 b, and XO-2 b. New mid-transit times extend the timespan covered by observations of these exoplanets and allow us to refine their transit ephemerides. All new transits are consistent with linear ephemerides
CARMENES detection of the Ca II infrared triplet and possible evidence of He I in the atmosphere of WASP-76b
Casasayas-Barris, N., et al.Ultra-hot Jupiters are highly irradiated gas giants with equilibrium temperatures typically higher than 2000 K. Atmospheric studies of these planets have shown that their transmission spectra are rich in metal lines, with some of these metals being ionised due to the extreme temperatures. Here, we use two transit observations of WASP-76b obtained with the CARMENES spectrograph to study the atmosphere of this planet using high-resolution transmission spectroscopy. Taking advantage of the two channels and the coverage of the red and near-infrared wavelength ranges by CARMENES, we focus our analysis on the study of the Ca II infrared triplet (IRT) at 8500 Å and the He I triplet at 10 830 Å. We present the discovery of the Ca II IRT at 7¿ in the atmosphere of WASP-76b using the cross-correlation technique, which is consistent with previous detections of the Ca II H&K lines in the same planet, and with the atmospheric studies of other ultra-hot Jupiters reported to date. The low mass density of the planet, and our calculations of the XUV (X-ray and EUV) irradiation received by the exoplanet, show that this planet is a potential candidate to have a He I evaporating envelope and, therefore, we performed further investigations focussed on this aspect. The transmission spectrum around the He I triplet shows a broad and red-shifted absorption signal in both transit observations. However, due to the strong telluric contamination around the He I lines and the relatively low signal-to-noise ratio of the observations, we are not able to unambiguously conclude if the absorption is due to the presence of helium in the atmosphere of WASP-76b, and we consider the result to be only an upper limit. Finally, we revisit the transmission spectrum around other lines such as Na I, Li I, H¿, and K I. The upper limits reported here for these lines are consistent with previous studies.We acknowledge funding from the European Research Council
under the European Union’s Horizon 2020 research and innovation program
under grant agreement no. 694513, the Agencia Estatal de Investigación of
the Ministerio de Ciencia, Innovación y Universidades and the ERDF through
projects PID2019-109522GB-C5[1:4]/AEI/10.13039/501100011033, PID2019-
110689RB-I00/AEI/10.13039/501100011033, ESP2017-87143-R, and ESP2016-
80435-C2-2-R, and the Centre of Excellence “Severo Ochoa” and “María de
Maeztu” awards to the Instituto de Astrofísica de Canarias (CEX2019-000920-
S), Instituto de Astrofísica de Andalucía (SEV-2017-0709), and Centro de
Astrobiología (MDM-2017-0737), and the Generalitat de Catalunya/CERCA programme. T.H. acknowledges support by the European Research Council under
the Horizon 2020 Framework Program via the ERC Advanced Grant Origins
83 24 28. G.M. has received funding from the European Union’s Horizon 2020
research and innovation programme under the Marie Skłodowska-Curie grant
agreement No. 895525
Transmission spectroscopy and Rossiter-McLaughlin measurements of the young Neptune orbiting AU Mic
AU Mic~b is a Neptune size planet on a 8.47-day orbit around the nearest
pre-main sequence (20 Myr) star to the Sun, the bright (V=8.81) M dwarf
AU Mic. The planet was preliminary detected in Doppler radial velocity time
series and recently confirmed to be transiting with data from the TESS mission.
AU Mic~b is likely to be cooling and contracting and might be accompanied by a
second, more massive planet, in an outer orbit. Here, we present the
observations of the transit of AU Mic~b using ESPRESSO on the VLT. We obtained
a high-resolution time series of spectra to measure the Rossiter-McLaughlin
effect and constrain the spin-orbit alignment of the star and planet, and
simultaneously attempt to retrieve the planet's atmospheric transmission
spectrum. These observations allow us to study for the first time the early
phases of the dynamical evolution of young systems. We apply different
methodologies to derive the spin-orbit angle of AU Mic~b, and all of them
retrieve values consistent with the planet being aligned with the rotation
plane of the star. We determine a conservative spin-orbit angle value
of , indicative that the formation and migration of
the planets of the AU Mic system occurred within the disk. Unfortunately, and
despite the large SNR of our measurements, the degree of stellar activity
prevented us from detecting any features from the planetary atmosphere. In
fact, our results suggest that transmission spectroscopy for recently formed
planets around active young stars is going to remain very challenging, if at
all possible, for the near future.Comment: Submitted to A&A, under second revie
High-resolution transmission spectroscopic studies of hot and ultra-hot Jupiters
Stars and planetary system
High-resolution transmission spectroscopy study of ultra-hot Jupiters HAT-P-57b, KELT-17b, KELT-21b, KELT-7b, MASCARA-1b, and WASP-189b
Stars and planetary system
The atmosphere of WASP-76b seen with CARMENES: looking for CaII IRT and HeI
Stars and planetary system
Discriminating between hazy and clear hot-Jupiter atmospheres with CARMENES
Context: Relatively large radii of some hot Jupiters observed in the
ultraviolet (UV) and blue-optical are generally interpreted to be due to
Rayleigh scattering by high-altitude haze particles. However, the haze
composition and its production mechanisms are not fully understood, and
observational information is still limited. Aims: We aim to study the presence
of hazes in the atmospheres of HD 209458 b and HD 189733 b with high spectral
resolution spectra by analysing the strength of water vapour cross-correlation
signals across the red optical and near-infrared wavelength ranges. Methods: A
total of seven transits of the two planets were observed with the CARMENES
spectrograph at the 3.5 m Calar Alto telescope. Their Doppler-shifted signals
were disentangled from the telluric and stellar contributions using the
detrending algorithm SYSREM. The residual spectra were subsequently
cross-correlated with water vapour templates at 0.70-0.96 m to measure the
strength of the water vapour absorption bands. Results: The optical water
vapour bands were detected at in HD 209458 b in one transit,
whereas no evidence of them was found in four transits of HD 189733 b.
Therefore, the relative strength of the optical water bands compared to those
in the near-infrared were found to be larger in HD 209458 b than in HD 189733
b. Conclusions: We interpret the non-detection of optical water bands in the
transmission spectra of HD 189733 b, compared to the detection in HD 209458 b,
to be due to the presence of high-altitude hazes in the former planet, which
are largely absent in the latter. This is consistent with previous measurements
with the Hubble Space Telescope. We show that currently available CARMENES
observations of hot Jupiters can be used to investigate the presence of haze
extinction in their atmospheres.Comment: 13 pages; accepted for publication in A&
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