Related papers: A 12-Year Activity Cycle for HD 219134
The cyclicity of 33 solar-type stars that are similar to 11-year and to the quasi-biennial variations of solar radiation have studied. Our calculation were based on new simultaneous observations of the flux variations of the photospheric…
We present a revised mass measurement for HD 119130 b (aka K2-292 b), a transiting planet ($P = 17$ days, $R_\mathrm{p} = 2.63^{+0.11}_{-0.10}$ $R_\mathrm{\oplus}$) orbiting a chromospherically inactive G dwarf, previously thought to be one…
We have measured transit times for HD 189733b passing in front of its bright (V = 7.67) chromospherically active and spotted parent star. Nearly continuous broadband optical photometry of this system was obtained with the MOST…
Using spectroscopic observations and photometric light curves of 238 nearby M dwarfs from the MEarth exoplanet transit survey, we examine the relationships between magnetic activity (quantified by H-alpha emission), rotation period, and…
Aims. Other stars are known to have magnetic cycles similar to that of the Sun. The relationship between these activity variations and the observed radial-velocity is still not satisfactorily understood. In this first paper our aim is to…
The components of the wide binary HD 219542 were recently found to differ in metallicity by about 0.1 dex (Gratton et al. A&A 377, 123). In this paper, we present the results of 2 years of high precision radial velocity monitoring of these…
The harvest of exoplanet discoveries has opened the area of exoplanet characterisation. But this cannot be achieved without a careful analysis of the host star parameters. The system of HD219134 hosts two transiting exoplanets and at least…
Context. Kepler-17 is a G2V sun-like star accompanied by a transiting planet with a mass of ~2.5 Jupiter masses and an orbital period of 1.486 d, recently discovered by the Kepler space telescope. This star is highly interesting as a young…
Earth-like planets orbiting in the habitable zone of K- to G-type stars create an RV effect in amplitude of less than 1 \si{\meter\per\second} and have orbital periods of hundreds of days. Only long-term RV surveys with sub-meter per second…
We present the discovery and characterization of a new transiting planet from Campaign 17 of the Kepler extended mission K2. HD 119130 b is a warm sub-Neptune on a 17-d orbit around a bright (V = 9.9 mag) solar-like G3 V star with a mass…
In recent years it has been claimed that the length of stellar activity cycles is determined by the stellar rotation rate. It is observed that the cycle period increases with rotation period along the so-called active and inactive…
We aim to detect activity cycles in young main-sequence stars, analogous to the 11-year solar cycle, using combined photometric survey data. This research will enhance our understanding of how cycle periods relate to rotation rates in…
The high-energy emission from low-mass stars is mediated by the magnetic dynamo. Although the mechanisms by which fully convective stars generate large-scale magnetic fields are not well understood, it is clear that, as for solar-type…
The presence of a planet around the K dwarf HD192263 was recently called into question by the detection of a periodic photometric signal with the same period as the one observed in radial velocity. In this paper, we investigate this…
Studying cool star magnetic activity gives an important insight into the stellar dynamo and its relationship with stellar properties, as well as allowing us to place the Sun's magnetism in the context of other stars. Only 61 Cyg A (K5V) and…
We report the discovery of two planets transiting the bright stars HD 89345 (EPIC 248777106, $V=9.376$, $K=7.721$) in K2 Campaign 14 and HD 286123 (EPIC 247098361, $V=9.822$, $K=8.434$) in K2 Campaign 13. Both stars are G-type stars, one of…
Context. The existence of a significant population of Ap stars with very long rotation periods (up to several hundred years) has progressively emerged over the past two decades. However, only lower limits of the periods are known for most…
We present the results of a spectroscopic and photometric analysis of HD314884, a slowly pulsating B star (SPB) in a binary system with detected soft X-ray emission. We spectrally classify the B star as a B5V-B6V star with T$_{eff}$ =…
About 30.5 days of nearly uninterrupted broadband photometry of the solar-type star Kappa1 Ceti, obtained with the MOST (Microvariability & Oscillations of STars) satellite, shows evidence for two large starspots with different rotation…
Context. The detection of chromospheric activity cycles in solar-analogue and twin stars, can be used to put in context the solar cycle. However, there is a relatively low percentage of these stars with activity cycles detected. It is well…