Related papers: Stellar activity of planetary host star HD 189733

We present results of radial-velocity follow-up observations for the two Kepler evolved stars Kepler-91 (KOI-2133) and KOI-1894, which had been announced as candidates to host transiting giant planets, with the Subaru 8.2m telescope and the…

[Abridged] After many attempts over more than a decade, high-resolution spectroscopy has recently delivered its first detections of molecular absorption in exoplanet atmospheres, both in transmission and thermal emission spectra. Targeting…

We observed stars with variable radial velocities to determine their spectroscopic orbits. Velocities of 132 targets taken over a time span reaching 30 years are presented. They were measured with the correlation radial velocity…

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…

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 present Spitzer Space Telescope observations of the extrasolar planet HD189733b primary transit, obtained simultaneously at 3.6 and 5.8 microns with the Infrared Array Camera. The system parameters, including planetary radius, stellar…

Accurately modeling effects from stellar activity is a key step in detecting radial velocity signals of low-mass and long-period exoplanets. Radial velocities from stellar activity are dominated by magnetic active regions that move in and…

We present a new primary transit observation of the hot-jupiter HD189733b, obtained at 3.6 microns with the Infrared Array Camera (IRAC) onboard the Spitzer Space Telescope. Previous measurements at 3.6 microns suffered from strong…

We present precision radial velocity (RV) data sets from Keck-HIRES and from Lick Observatory's new Automated Planet Finder Telescope and Levy Spectrometer on Mt. Hamilton that reveal a multiple-planet system orbiting the nearby, slightly…

We report the detection of a Jupiter-mass planet in a 6.838 day orbit around the 1.28 solar mass subgiant HD 185269. The eccentricity of HD 185269b (e = 0.30) is unusually large compared to other planets within 0.1 AU of their stars.…

There is a small group of peculiar early-type stars on the main sequence that show different rotation velocities from different spectral lines. This inconsistency might be due to the binary nature of these objects. We aim to verify this…

We investigate the effect of planetary rotation on the transit spectrum of an extrasolar giant planet. During ingress and egress, absorption features arising from the planet's atmosphere are Doppler shifted by of order the planet's…

From a long-term Doppler monitoring campaign of 373 giant stars, we have identified ten giants with periodic radial velocity variations that are challenging to associate with planets. Similar cases in the literature are attributed to poorly…

The magnetic fields, activity and dynamos of young solar-type stars can be empirically studied using time-series of spectropolarimetric observations and tomographic imaging techniques such as Doppler imaging and Zeeman Doppler imaging. In…

The young active G-dwarf star V889 Herculis (HD 171488) shows pronounced spots in Doppler images as well as large variations in photometry and radial velocity (RV) measurements. However, the lifetime and evolution of its active regions are…

We have analysed oscillations of the red giant star HD 186355 observed by the NASA Kepler satellite. The data consist of the first five quarters of science operations of Kepler, which cover about 13 months. The high-precision time-series…

Future generations of precise radial velocity (RV) surveys aim to achieve sensitivity sufficient to detect Earth mass planets orbiting in their stars' habitable zones. A major obstacle to this goal is astrophysical radial velocity noise…

Detailed models are compared to recent infrared observations of the nearby extrasolar planet, HD 189733b. It is demonstrated that atmospheric water is present and that the planet's day side has a non-isothermal structure down to gas…

We present the results of time-resolved photometry, abundance analysis and Doppler imaging of an Ap star, HD 100357. The {\it TESS} photometry revealed rotational modulation with a period of 1.6279247 days. Upon inspecting the residuals…

We present high-precision radial velocity (RV) observations of four solar-type (F7-G5) stars - HD 79498, HD 155358, HD 197037, and HD 220773 - taken as part of the McDonald Observatory Planet Search Program. For each of these stars, we see…