Related papers: Multi-Site observations of SU Aurigae
Radio bursts of magnetically active stars reveal the intensity and activity of the stellar magnetic field. They may also be related to the planets around the stars. We monitored a radio-active star, AD Leonis, 3000 seconds per day for 17…
We present a detailed temperature and magnetic investigation of the T Tauri star V410 Tau by means of a simultaneous Doppler- and Zeeman-Doppler Imaging. Moreover we introduce a new line profile reconstruction method based on a singular…
From a long time series of high resolution (R=115,000) HARPS spectra and simultaneous broad-band photometry, we report new evidence for magnetospheric accretion as well as ejection processes in the nearly edge-on classical T Tauri star AA…
A new time series of high-resolution Stokes I and V spectra of the magnetic B2V star HD 184927 has been obtained in the context of the Magnetism in Massive Stars (MiMeS) Large Program with the ESPaDOnS spectropolarimeter at the…
We present CCD photometric observations of the slow irregular type variable KU Her. We have also used observations from the ASAS Database and the AAVSO International Database. The V-band observations span eight years from August of 2002 to…
We present new optical and infrared photometric observations and high resolution H$\alpha$ spectra of the periodic radio star \lsi. The optical photometric data set covers the time interval 1985-1993 and amounts to about a hundred nights. A…
We present here the first results of UVES observations of RR Tel. The exceptional performances of the instrument have allowed the detection of new spectral features and have led to an improvement in the identifications of several emission…
Our knowledge of the presence and the role of magnetic fields in intermediate-mass pre-main-sequence stars remains very poor. We present the magnetic properties of four Herbig Ae/Be stars that have not been previously studied in detail. Our…
We present an analysis of high-resolution ($R \sim 50,000$) infrared K-band echelle spectra of 14 T Tauri stars in the Orion Nebula Cluster. We model Zeeman broadening in three magnetically sensitive \ion{Ti}{1} lines near $2.2\ \mu$m and…
We present the discovery of two extended $\sim$0.12 mag dimming events of the weak-lined T-Tauri star V1334. The start of the first event was missed but came to an end in late 2003, and the second began in February 2009, and continues as of…
Long-term, uniform series of UBVR observations of T Tauri and Herbig Ae stars obtained over 20 yr at the Maidanak Observatory as part of the ROTOR program are analyzed. We find a linear relationship between the characteristic variability…
The more massive counterparts of T Tauri stars, Herbig Ae/Be stars, are known to vary in a complex way with no variability mechanism clearly identified. We attempt to characterize the optical variability of HD~37806 (MWC 120) on time scales…
Classical T Tauri stars (CTTS) are young, late-type objects, that still accrete matter from a circumstellar disk. Analytical treatments and numerical simulations predict instabilities of the accretion shock on the stellar surface. We search…
We present photometric observations of RW Aurigae, a Classical T Tauri system, that reveal two remarkable dimming events. These events are similar to that which we observed in 2010-2011, which was the first such deep dimming observed in RW…
Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the…
T Tauri stars are low-mass pre-main sequence stars that are intrinsically variable. Due to the intense magnetic fields they possess, they develop dark spots on their surface that, because of rotation, introduce a periodic variation of…
Stellar radio emission can measure a star's magnetic field strength and structure, plasma density and dynamics, and the stellar wind pressure impinging on exoplanet atmospheres. However, properly interpreting the radio data often requires…
We present time-series Doppler images of the rapidly-rotating active binary star EI Eri from spectroscopic observations collected during the MUSICOS multi-site campaign in 1998, since the critical rotation period of 1.947 days makes it…
Context. The first magnetic fields in O- and B-type stars that do not belong to the Bp-star class, have been discovered. The cyclic UV wind-line variability, which has been observed in a significant fraction of early-type stars, is likely…
We present first results of a survey for companions among X-ray selected pre-main sequence stars, most of them being weak-line T Tauri stars (WTTS). These T Tauri stars have been identified in the course of optical follow-up observations of…