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The analysis of exoplanetary atmospheres by means of high-resolution spectroscopy is an expanding research field which provides information on chemical composition, thermal structure, atmospheric dynamics and orbital velocity of exoplanets.…
At optical wavelengths, an exoplanet's signature is essentially reflected light from the host star - several orders of magnitude fainter. Since it is superimposed on the star spectrum its detection has been a difficult observational…
The extreme contrast ratios between stars and their planets at optical wavelengths make it challenging to isolate the light reflected by exoplanet atmospheres. Yet, these reflective properties reveal key processes occurring in the…
We consider an alternative to the cross-correlation function (CCF), that uses the autocor- relation function (ACF), to measure in spectra the reflected light of the stars by their planetary companion. The objective of this work is to assess…
The direct detection of reflected light from exoplanets is an excellent probe for the characterization of their atmospheres. The greatest challenge for this task is the low planet-to-star flux ratio, which even in the most favourable case…
In this paper we explore the possibility that the recently detected reflected light signal of 51\,Peg\,b could be caused by a ring system around the planet. We use a simple model to compare the observed signal with the expected signal from…
We present high-precision linear polarization observations of four bright hot Jupiter systems ($\tau$ Boo, HD 179949, HD 189733 and 51 Peg) and use the data to search for polarized reflected light from the planets. The data for 51 Peg are…
It is challenging to measure the starlight reflected from exoplanets because of the extreme contrast with their host stars. For hot Jupiters, this contrast is in the range of $10^{-6}$ to $10^{-4}$, depending on their albedo, radius and…
So far, the atmospheres of non-transiting exoplanets remain poorly explored, and the potential of high-resolution spectroscopy for determining key planetary parameters beyond their atmospheric properties has not been fully exploited. We…
NASA's Kepler Mission promises to detect transiting Earth-sized planets in the habitable zones of solar-like stars. In addition, it will be poised to detect the reflected light component from close-in extrasolar giant planets (CEGPs)…
Aims. We attempt to detect starlight reflected from the hot Jupiter orbiting the main-sequence star Tau Boo, in order to determine the albedo of the planetary atmosphere, the orbital inclination of the planetary system and the exact mass of…
The characterization of exoplanet atmospheres has proven to be successful using high-resolution spectroscopy. Phase curve observations of hot/ultra-hot Jupiters can reveal their compositions and thermal structures, thereby allowing the…
A space telescope capable of high-contrast imaging has been recognized as the avenue toward finding terrestrial planets around nearby Sun-like stars and characterizing their potential habitability. It is thus essential to quantify the…
Giant planets orbiting stars other than the Sun are clearly detectable through precise radial-velocity measurements of the orbital reflex motion of the parent star. In the four years since the discovery of the companion to the star 51 Peg,…
Context. Spectroscopy of exoplanet atmospheres at high resolving powers is rapidly gaining popularity to measure the presence of atomic and molecular species. While this technique is robust against contaminant absorption in the Earth's…
[Abridged] Recently, there have been a series of detections of molecules in the atmospheres of extrasolar planets using high spectral resolution (R~100,000) observations, mostly using the CRyogenic high-resolution InfraRed Echelle…
High-resolution Doppler-resolved spectroscopy has opened up a new window into the atmospheres of both transiting and non-transiting exoplanets. Here, we present VLT/UVES observations of a transit of WASP-121b, an 'ultra-hot' Jupiter…
The largest and most close-in exoplanets would reflect enough star light to enable its ground-based photometric detection under the condition of a high to moderate albedo. We present the results of an observing campaign of secondary eclipse…
We present a new method for performing atmospheric retrieval on ground-based, high-resolution data of exoplanets. Our method combines cross-correlation functions with a random forest, a supervised machine learning technique, to overcome…
Direct imaging of exoplanets will allow us to directly observe the planet in reflected light. Such a scenario may eventually allow for the possibility to scan the planetary surface for the presence of artificial structures made by alien…