Related papers: Rotation Effects in Classical T Tauri Stars

FU Tau A is a young very low mass object in the Taurus star forming region which was previously found to have strong X-ray emission and to be anomalously bright for its spectral type. In this study we discuss these characteristics using new…

We analyze the variability in accretion-related emission lines for 40 Classical T Tauri stars to probe the extent of accretion variations in young stellar objects. Our analysis is based on multi-epoch high-resolution spectra for young stars…

We report the results of a spectroscopic survey of 20 close T Tauri binaries in the Taurus-Auriga dark cloud where the separations between primaries and their secondaries are less than the typical size of a circumstellar disk around a young…

We present results from a Near Infrared multi-epoch spectroscopic campaign to detect a young low-mass companion to a T Tauri star. AS 205A is a late-type dwarf (~K5) of ~1 Msun that belongs to a triple system. Independent photometric…

We present numerical solutions of the collapse of prestellar cores that lead to the formation and evolution of circumstellar disks. The disk evolution is then followed for up to three million years. A variety of models of different initial…

We have discovered T Tauri stars which show startling spectral variability between observations seperated by 20 years. In spectra published by Bouvier & Appenzeller (1992) these objects showed very weak H-alpha emission, broad CaII…

Using the UVES echelle spectrograph at the ESO VLT we obtained two-dimensional high-resolution (R = 50 000) spectra of the edge-on disk objects HH30*, HK Tau B, and HV Tau C. For comparison purposes we also observed with the same equipment…

This article summarizes the processes of high-energy emission in young stellar objects. Stars of spectral type A and B are called Herbig Ae/Be (HAeBe) stars in this stage, all later spectral types are termed classical T Tauri stars (CTTS).…

The classical T Tauri star RW Aur A is an irregular variable with a large amplitude in all photometric bands. In an extended series of photometric data we found small-amplitude periodic variations in the blue colours of the star, with a…

We investigate the rotational equilibrium state of a disk accreting magnetized stars using axisymmetric magnetohydrodynamic (MHD) simulations. In this ``locked'' state, the spin-up torque balances the spin-down torque so that the net…

Rapidly rotating stars have been recently recognized as having a major role in the interpretation of colour-magnitude diagrams of young and intermediate-age star clusters in the Magellanic Clouds and in the Milky Way. In this work, we…

High-precision space-based photometry obtained by the \emph{Kepler} and \emph{TESS} missions has revealed evidence of rotational modulation associated with main sequence (MS) A and late-B type stars. Generally, such variability in these…

We investigate the photometric modulation induced by magnetic activity cycles and study the relationship between rotation period and activity cycle(s) in late-type (FGKM) stars. We analyse light-curves spanning up to 9 years of 125 nearby…

As part of the Young Exoplanets Spectroscopic Survey (YESS), this study explores the spot variability of 13 T Tauri Stars (TTSs) in the near-infrared $H$ band, using spectra from the Immersion GRating INfrared Spectrometer (IGRINS). By…

The 76 frequencies determined from Kepler measurements of the A-type star KIC 9700322 can be understood in a rather simple way as the radial fundamental and first overtone radial modes, a nonradial \ell = 2 quintuplet, stellar rotation and…

We argue that classical T Tauri stars (cTTs) possess significant non- photospheric excess in the J and H bands. We first show that normalizing the spectral energy distributions (SEDs) of cTTs to the J-band leads to a poor fit of the optical…

We have derived new orbits for zeta Aur, 32 Cyg, and 31 Cyg with observations from the TSU Automatic Spectroscopic Telescope and used them to identify non-orbital velocities of the cool supergiant components of these systems. We measure…

We report initial results from a quasi-simultaneous X-ray/optical observing campaign targeting V4046 Sgr, a close, synchronous-rotating classical T Tauri star (CTTS) binary in which both components are actively accreting. V4046 Sgr is a…

We employ a Monte Carlo radiation transfer code to investigate the multi- wavelength photopolarimetric variability arising from a spotted T Tauri star surrounded by a dusty circumstellar disk. Our aim is to assess the ability of the…

We present rotation periods for thousands of active stars in the Kepler field derived from Q3 data. In most cases a second period close to the rotation period was detected, which we interpreted as surface differential rotation (DR). Active…