145 research outputs found
Detection of sodium in the atmosphere of WASP-69b
Transit spectroscopy is one of the most commonly used methods to characterize
exoplanets atmospheres. From the ground, these observations are very
challenging due to the terrestrial atmosphere and its intrinsic variations, but
high-spectral resolution observations overcome this difficulty by resolving the
spectral lines and taking advantage of the different Doppler velocities of the
Earth, the host star and the exoplanet. We analyze the transmission spectrum
around the Na I doublet at 589 nm of the exoplanet WASP-69b, a hot Jupiter
orbiting a K-type star with a period of 3.868 days, and compare the analysis to
that of the well-know hot Jupiter HD 189733b. We also present the analysis of
the Rossiter-McLaughlin effect for WASP-69b. Two transits of WASP-69b were
observed with the HARPS-North spectrograph (R = 115 000) at the TNG telescope.
We perform a telluric contamination subtraction based on the comparison between
the observed spectra and a telluric water model. Then, the common steps of the
differential spectroscopy are followed to extract the transmission spectrum.
The method is tested with archival transit data of the extensively studied
exoplanet HD 189733b, obtained with the HARPS-South spectrograph at ESO 3.6m
telescope, and then applied to WASP-69b data. For HD 189733b, we spectrally
resolve the Na I doublet and measure line contrasts of (D2) and
(D1), and FWHMs of {\AA} (D2) and
{\AA} (D1), in agreement with previously published results. A net
blueshift of {\AA} is measured. For WASP-69b only the contrast of
the D2 line is measured (). Even if this corresponds to a
detection at the -level of excess absorption of in a
passband of {\AA}, more transits are needed to fully characterize the
lines profiles and retrieve accurate atmospheric properties.Comment: 15 pages, 14 figure
Let's have CHOCOLATE: an alternative technique for broadband transmission spectroscopy
Stars and planetary system
Let's have CHOCOLATE: an alternative technique for broadband transmission spectroscopy
Stars and planetary system
Retrieving the transmission spectrum of HD 209458b using CHOCOLATE: a new Chromatic Doppler Tomography technique
Stars and planetary system
Detection of Fe I and Fe II in the atmosphere of MASCARA-2b using a cross-correlation method
Ultra-hot Jupiters are gas giants planets whose dayside temperature, due to
the strong irradiation received from the host star, is greater than 2200 K.
These kind of objects are perfect laboratories to study chemistry of
exoplanetary upper atmospheres via transmission spectroscopy. Exo-atmospheric
absorption features are buried in the noise of the in-transit residual spectra.
However we can retrieve the information of hundreds of atmospheric absorption
lines by performing a cross-correlation with an atmospheric transmission model,
which allows us to greatly increase the exo-atmospheric signal. At the
high-spectral resolution of our data, the Rossiter-McLaughlin effect and
centre-to-limb variation have a strong contribution. Here, we present the first
detection of Fe I and the confirmation of absorption features of Fe II in the
atmosphere of the ultra-hot Jupiter MASCARA-2b/KELT-20b, by using three transit
observations with HARPS-N. After combining all transit observations we find a
high cross-correlation signal of Fe I and Fe II with signal-to-noise ratios of
10.5 +/- 0.4 and 8.6 +/- 0.5, respectively. The peak absorption for both
species appear to be blue-shifted with velocities of -6.3 +/- 0.8 km/s for Fe I
and -2.8 +/- 0.8 km/s for Fe II, suggesting the presence of winds from the day-
to night-side of the planet's atmosphere. These results confirm previous
studies of this planet and add a new atomic species (Fe I) to the long list of
detected species in the atmosphere of MASCARA-2b, making it, together with
KELT-9b, the most feature-rich ultra-hot Jupiter to date.Comment: 10 pages, 7 figure
A feature-rich transmission spectrum for WASP-127b
WASP-127b is one of the lowest density planets discovered to date. With a
sub-Saturn mass () and super-Jupiter radius
(), it orbits a bright G5 star, which is about to
leave the main-sequence. We aim to explore WASP-127b's atmosphere in order to
retrieve its main atmospheric components, and to find hints for its intriguing
inflation and evolutionary history. We used the ALFOSC spectrograph at the NOT
telescope to observe a low resolution (, seeing limited) long-slit
spectroscopic time series during a planetary transit, and present here the
first transmission spectrum for WASP-127b. We find the presence of a strong
Rayleigh slope at blue wavelengths and a hint of Na absorption, although the
quality of the data does not allow us to claim a detection. At redder
wavelengths the absorption features of TiO and VO are the best explanation to
fit the data. Although higher signal-to-noise ratio observations are needed to
conclusively confirm the absorption features, WASP-127b seems to posses a
cloud-free atmosphere and is one of the best targets to perform further
characterization studies in the near future.Comment: Accepted for Publication A&A Letters, May 22nd, 201
Spatial characterization of the trailing and leading limbs of WASP-76b: detection of H2O and HCN at high-resolution
Stars and planetary system
A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b
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 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 K. Such a strong temperature inversion is
probably created by the absorption of atomic species like Fe I.Comment: 9 pages, 10 figures. Accepted for publication in Astronomy &
Astrophysics, in pres
The strange case of Na I in the atmosphere of HD 209458 b: reconciling low- and high-resolution spectroscopic observations
Stars and planetary system
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