Related papers: Spectral Line Depth Variability in Radial Velocity…
Diagnostic potential of the spectral signatures of Raman scattering imprinted in planetary albedo spectra at short optical wavelengths has been demonstrated in research on Solar System planets and has recently been proposed as a probe of…
We cross-match the GALEX and Kepler surveys to create a unique dataset with both ultraviolet (UV) measurements and highly precise photometric variability measurements in the visible light spectrum. As stellar activity is driven by magnetic…
Stellar activity patterns are responsible for jitter effects that are observed at different timescales and amplitudes. These effects are currently in the focus of many exoplanet search projects, since the lack of a well-defined…
An extensive spectroscopic study on \xi Boo A (chromospherically active solar-type star) was conducted based on the spectra obtained in 2008 December though 2010 May, with an aim to detect any spectrum variability and to understand its…
Magnetic fields and stellar spots can alter the equivalent widths of absorption lines in stellar spectra, varying during the activity cycle. This also influences the information that we derive through spectroscopic analysis. In this study…
Spectroscopic measurements of Mira variable stars, as a function of phase, probe the stellar atmospheres and underlying pulsation mechanisms. For example, measuring variations in TiO, VO, and ZrO with phase can be used to help determine…
This work reports the discovery of cycle-to-cycle modulated spectral line and atmospheric velocity gradient variability in long-period Cepheids based on 925 high-resolution optical spectra of $\ell$ Carinae (P $\sim$ 35.5 d) recorded during…
Aims: We investigate whether bisectors derived from cross-correlation functions (CCF) of single-exposure spectra can be used to provide information on stellar atmospheres, and whether they can be used to discriminate between radial velocity…
Previous simulations predicted the activity-induced radial-velocity (RV) variations of M dwarfs to range from $\sim1$ cm/s to $\sim1$ km/s, depending on various stellar and activity parameters. We investigate the observed relations between…
The measurement of exoplanet masses using the radial velocity (RV) technique is currently limited by stellar activity, which introduces quasiperiodic variability signals that must be modeled and removed to enhance the sensitivity of the RV…
For the 451 stars of the HARPS high precision program, we study correlations between the radial-velocity (RV) variation and other parameters of the Cross Correlated Function (CCF). After a careful target selection, we found a very good…
Phase curves, or the change in observed illumination of the planet as it orbits around its host star, help us to characterize their atmospheres. However, the variability of the host star can make their detection challenging: the presence of…
The discovery and characterization of exoplanets around nearby stars is driven by profound scientific questions about the uniqueness of Earth and our Solar System, and the conditions under which life could exist elsewhere in our Galaxy.…
Given their strong stellar winds, Wolf-Rayet (WR) stars exhibit emission line spectra that are predominantly formed in expanding atmospheric layers. The description of the wind velocity field $v(r)$ is therefore a crucial ingredient in the…
The planet-star interaction is manifested in many ways. It was found out that a close-in exoplanet causes small but measurable variability in the cores of a few lines in the spectra of several stars which corresponds to the orbital period…
The UV/optical variation, likely driven by accretion disc turbulence, is a defining characteristic of type 1 active galactic nuclei (AGNs) and quasars. In this work we investigate an interesting consequence of such turbulence using quasars…
The effect of stellar activity on RV appears to be a limiting factor in detecting Earth-mass planets in the habitable zone of a star similar to the Sun in spectral type and activity level. It is crucial to estimate if this conclusion remain…
In our former paper I, we showed on the Sun that different active regions possess unique intensity profiles on the Ca II H & K lines. We now extend the analysis by showing how those properties can be used on real stellar observations,…
Stellar activity variability is one of the main obstacles to the detection of Earth-like planets using the RV method. The aim of this work is to measure the effect of activity in the spectra of M dwarfs and detect activity-sensitive lines…
We conducted speckle imaging observations of 53 stellar systems that were members of long-term radial velocity (RV) monitoring campaigns and exhibited substantial accelerations indicative of planetary or stellar companions in wide orbits.…