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 $0.72\pm0.05\%$ (D2) and $0.51\pm0.05\%$ (D1), and FWHMs of $0.64\pm0.04${\AA} (D2) and $0.60\pm0.06${\AA} (D1), in agreement with previously published results. A net blueshift of ${\sim}0.04${\AA} is measured. For WASP-69b only the contrast of the D2 line is measured ($5.8\pm0.3\%$). Even if this corresponds to a detection at the $5\sigma$-level of excess absorption of $0.5\pm0.1\%$ in a passband of $1.5${\AA}, more transits are needed to fully characterize the lines profiles and retrieve accurate atmospheric properties.Comment: 15 pages, 14 figure

Narrow band transmission spectroscopy

Stars and planetary system

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 ($M_{\rm p}=0.18 \pm 0.02 M_J$) and super-Jupiter radius ($R_{\rm p}= 1.37 \pm 0.04 R_J$), 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 ($R\sim330$, 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 $4320_{-100}^{+120}$ 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 $2200_{-800}^{+1000}$ 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