Related papers: Revisiting K2-233 spectroscopic time-series with m…
Theoretical predictions suggest that the distribution of planets in very young stars could be very different to that typically observed in Gyr old systems that are the current focus of radial velocity surveys. However, the detection of…
We revisit the analysis of the bright multiplanet system K2-93, discovered with data taken by the K2 mission. This system contains five identified planets ranging in size from sub-Neptune to Jupiter size. The K2 data available at the…
We present the results of radial velocity measurements of two samples of active stars. The first sample contains field G and K giants across the Red Giant Branch, whereas the second sample consists of nearby young stars (d < 150 pc) with…
Discovering exoplanets orbiting young Suns can provide insight into the formation and early evolution of our own solar system, but the extreme magnetic activity of young stars obfuscates exoplanet detection. Here we monitor the long-term…
We explore the feasibility of detecting Earth analogs around Sun-like stars using the radial velocity method by investigating one of the largest radial velocities datasets for the one of the most stable radial-velocity stars HD20794. We…
The radial velocity method is one of the most successful techniques for the discovery and characterization of exoplanets. Modern spectrographs promise measurement precision of ~0.2-0.5 m/s for an ideal target star. However, the intrinsic…
To date, only 18 exoplanets with radial velocity (RV) semi-amplitudes $<2$ m/s have had their masses directly constrained. The biggest obstacle to RV detection of such exoplanets is variability intrinsic to stars themselves, e.g. nuisance…
Stellar photospheric activity is known to limit the detection and characterisation of extra-solar planets. In particular, the study of Earth-like planets around Sun-like stars requires data analysis methods that can accurately model the…
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 four-planet system around GJ 581 has received attention because it has been claimed that there are possibly two additional low-mass companions as well - one of them being a planet in the middle of the stellar habitable zone. We…
Detecting and characterising exoworlds around very young stars (age$<$10 Myr) are key aspects of exoplanet demographic studies, especially for understanding the mechanisms and timescales of planet formation and migration. However, detection…
Stellar active regions like spots and faculae can distort the shapes of spectral lines, inducing variations in the radial velocities that are often orders of magnitude larger than the signals from Earth-like planets. Efforts to mitigate…
The meter-per-second precision achieved by today velocimeters enables the search for 1-10 M_Earth planets in the habitable zone of cool stars. This paper reports on the detection of 3 planets orbiting GJ163 (HIP19394), a M3 dwarf monitored…
Accounting for stellar activity is a crucial component of the search for ever-smaller planets orbiting stars of all spectral types. We use Doppler imaging methods to demonstrate that starspot induced radial velocity variability can be…
We re-analyse the recently published HARPS and PFS velocities of the nearby K dwarf GJ 221 that have been reported to contain the signatures of two planets orbiting the star. Our goal is to see whether the earlier studies discussing the…
Context. Searching for extrasolar planets through radial velocity measurements relies on the stability of stellar photospheres. Aims. We aim at characterizing the statistical properties of magnetic activity cycles, and studying their impact…
In an effort to measure the masses of planets discovered by the NASA {\it K2} mission, we have conducted precise Doppler observations of five stars with transiting planets. We present the results of a joint analysis of these new data and…
We performed a radial velocity (RV) monitoring of the 40 Myr old star DS Tuc A with HARPS at the ESO-3.6m to determine the planetary mass of its 8.14-days planet, first revealed by TESS. We also observed two planetary transits with HARPS…
Exoplanets of a few Earth masses can be now detected around nearby low-mass stars using Doppler spectroscopy. In this paper, we investigate the radial velocity variations of Kapteyn's star, which is both a sub-dwarf M-star and the nearest…
Due to their higher planet-star mass-ratios, M dwarfs are the easiest targets for detection of low-mass planets orbiting nearby stars using Doppler spectroscopy. Furthermore, because of their low masses and luminosities, Doppler…