Related papers: The transiting exoplanet host star GJ 436: a test …
Neptune-sized extrasolar planets that orbit relatively close to their host stars -- often called "hot Neptunes" -- are common within the known population of exoplanets and planetary candidates. Similar to our own Uranus and Neptune,…
The atmospheres of close-in planets are strongly influenced by mass loss driven by the high-energy (X-ray and extreme ultraviolet, EUV) irradiation of the host star, particularly during the early stages of evolution. We recently developed a…
Exoplanet Doppler surveys are currently the most efficient means to detect low-mass companions to nearby stars. Among these stars, the light M dwarfs provide the highest sensitivity to detect low-mass exoplanet candidates. Evidence is…
The super-Earth GJ1214b transits a nearby M dwarf that exhibits 1% intrinsic variability in the near-infrared. Here, we analyze new observations to refine the physical properties of both the star and planet. We present three years of…
We use near-infrared interferometric data coupled with trigonometric parallax values and spectral energy distribution fitting to directly determine stellar radii, effective temperatures, and luminosities for the exoplanet host stars 61 Vir,…
Although the number of exoplanets reported in the literature exceeds 5000 so far, only a few dozen of them are young planets ($\le$900 Myr). However, a complete characterization of these young planets is key to understanding the current…
Context. Low mass stars are currently the best targets for searches for rocky planets in the habitable zone of their host star. Over the last 13 years, precise radial velocities measured with the HARPS spectrograph have identified over a…
The detection of transits is an efficient technique to uncover faint companions around stars. The full characterisation of the companions (M-type stars, brown dwarfs or exoplanets) requires high-resolution spectroscopy to measure properly…
The Galactic halo preserves a record of the Milky Way's earliest assembly and contains both in-situ stars and stars accreted from dwarf galaxies. Possible planets around these stars, therefore, probe formation in ancient, metal-poor…
Context: To date, more than 30 planets have been discovered around giant stars, but only one of them has been found to be orbiting within 0.6 AU from the host star, in direct contrast to what is observed for FGK dwarfs. This result suggests…
Lyman-alpha (Lya) emission of neutral hydrogen (1215.67 Angstr\"om) is the main contributor to the ultraviolet flux of low-mass stars such as M dwarfs. It is also the main light source used in studies of the evaporating upper atmospheres of…
Planets orbiting M-dwarf stars are prime targets in the search for rocky exoplanet atmospheres. The small size of M dwarfs renders their planets exceptional targets for transmission spectroscopy, facilitating atmospheric characterization.…
Recent discoveries of transiting giant exoplanets around M-dwarf stars (GEMS), aided by the all-sky coverage of TESS, are starting to stretch theories of planet formation through the core-accretion scenario. Recent upper limits on their…
Of the nearby transiting exoplanets that are amenable to detailed study, TrES-2 is both the most massive and has the largest impact parameter. We present z-band photometry of three transits of TrES-2. We improve upon the estimates of the…
Statistical analyses of large surveys for transiting planets such as the Kepler mission must account for systematic errors and biases. Transit detection depends not only on the planet's radius and orbital period, but also on host star…
The Kepler Spacecraft has discovered a large number of planets up to one-year periods and down to terrestrial sizes. While the majority of the target stars are main-sequence dwarfs of spectral type F, G, and K, Kepler covers stars with…
Surveys for exoplanets indicate that the occurrence rate of gas giant planets orbiting late-type stars in orbits with periods shorter than 1000 days is lower than in the case of Sun-like stars. This is in agreement with planet formation…
GJ 581 is an M dwarf host of a multiplanet system. We use long-baseline interferometric measurements from the CHARA Array, coupled with trigonometric parallax information, to directly determine its physical radius to be $0.299 \pm 0.010…
The recent announcement of a Neptune-sized exomoon candidate around the transiting Jupiter-sized object Kepler-1625 b could indicate the presence of a hitherto unknown kind of gas giant moons, if confirmed. Three transits have been…
For more than two years, we monitored with the HARPS-N spectrograph the 400 Myr-old star HD\,63433, which hosts two close-in (orbital periods $P_b\sim7.1$ and $P_c\sim20.5$ days) sub-Neptunes detected by the TESS space telescope, and it was…