Related papers: First Doppler image and starspot-corrected orbit f…

The (Zeeman-)Doppler imaging studies of solar-type stars very often reveal large high-latitude spots. This also includes F stars that possess relatively shallow convection zones, indicating that the dynamo operating in these stars differs…

We report extensive radial-velocity measurements of the two giant components of the detached, 104-day period binary system of Capella. Our highly accurate three-dimensional orbital solution based on all existing spectroscopic and…

Stellar activity induces apparent radial velocity (RV) variations in late-type main-sequence stars that may hamper the detection of low-mass planets and the measurement of their mass. We use simultaneous measurements of the active planet…

We derive the absolute physical and orbital parameters for a sample of 18 detached eclipsing binaries from the \emph{All Sky Automated Survey} (ASAS) database based on the available photometry and our own radial velocity measurements. The…

Frequency analysis of long-term ultra-precise photometry can lead to precise values of rotation frequencies of rotating stars with ``hump and spike'' features in their periodograms. Using these features, we computed the rotation frequencies…

Doppler Imaging produces 2D global maps of rotating objects using high-dispersion spectroscopy. When applied to brown dwarfs and extrasolar planets, this technique can constrain global atmospheric dynamics and/or magnetic effects on these…

Dark spots on the surface of active stars produce changes in the shapes of the spectral lines that mimic spurious Doppler shifts, compromising the detection of small planets by means of the radial velocity (RV) technique. Modelling the…

We present the first detailed spectroscopic and photometric analysis of an eclipsing binary in the Andromeda Galaxy (M31). This is a 19.3-mag semi-detached system with components of late-O and early-B spectral types. From the light and…

The Hyades K2V+WD system 471 Tau is a prototype post-common envelope system and a likely cataclysmic binary progenitor. We present 10 days of nearly continuous optical photometry by the MOST (Microvariability & Oscillations of STars)…

The Ch-type asteroid (130) Elektra is orbited by three moons, making it the first quadruple system in the main asteroid belt. We aim to characterise the irregular shape of Elektra and construct a complete orbital model of its unique moon…

We present the first orbital elements for the massive close binary, HD 115071, a double-lined spectroscopic binary in a circular orbit with a period of 2.73135 +/- 0.00003 days. The orbital semiamplitudes indicate a mass ratio of M_2/M_1 =…

Young, rapidly-rotating M dwarfs exhibit prominent starspots, which create quasiperiodic signals in their photometric and Doppler spectroscopic measurements. The periodic Doppler signals can mimic radial velocity (RV) changes expected from…

Rapid rotation enhances the dynamo operating in stars, and thus also introducessignificantly stronger magnetic activity than is seen in slower rotators. Many young cool stars still have the rapid, primordial rotation rates induced by the…

We study the short-term evolution of starspots on the ultrafast-rotating star HD197890 ("Speedy Mic" = BO Mic, K 0-2V, P_rot = 0.380 d) based on two Doppler images taken about 13 stellar rotations apart. Each image is based on spectra…

We present multi-epoch spectroscopy of "heartbeat stars," eccentric binaries with dynamic tidal distortions and tidally induced pulsations originally discovered with the Kepler satellite. Optical spectra of six known heartbeat stars using…

We present differential $UBV$ photoelectric photometry obtained by Williamon of the short-period A-type W~UMa binary MW~Pav. With the Wilson-Devinney analysis program we obtained a simultaneous solution of these observations with the $UBV$…

During the solar magnetic activity cycle the emergence latitudes of sunspots change, leading to the well-known butterfly diagram. This phenomenon is poorly understood for other stars as starspot latitudes are generally unknown. The related…

We present Roche tomograms of the K4V secondary star in the cataclysmic variable AE Aqr, reconstructed from two datasets taken 9 days apart, and measure the differential rotation of the stellar surface. The tomograms show many large, cool…

Among the initial results from Kepler were two striking lightcurves, for KOI 74 and KOI 81, in which the relative depths of the primary and secondary eclipses showed that the more compact, less luminous object was hotter than its stellar…

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…