Related papers: A Long-Lived Accretion Disk Around a Lithium-Deple…

Classical T Tauri stars with ages of less than 10 Myr possess accretion discs. Magnetohydrodynamic processes at the boundary between the disc and the stellar magnetosphere control the accretion and ejections gas flows. We carried out a long…

Young stars and planetary systems form in molecular clouds. For classical T Tauri stars (CTTS, F-K type precursors) the accretion disk does not reach down to the central star, but it is truncated near the co-rotation radius. The inner edge…

We report on the discovery of the young, nearby, brown dwarf 2MASS J0041353$-$562112. The object has a spectral type of M7.5, it shows Li absorption and signatures of accretion, which implies that it still has a disk and suggests an age…

Following up our recent analysis devoted to the impact of non steady accretion on the location of young low-mass stars or brown dwarfs in the Herzsprung-Russell diagram, we perform a detailed analysis devoted to the effect of burst…

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 present the Spitzer Infrared Spectrograph (IRS) spectrum of SR20, a 5--10 AU binary T Tauri system in the $\rho$ Ophiuchi star forming region. The spectrum has features consistent with the presence of a disk; however, the continuum slope…

We present a spectral analysis of 30 T Tauri stars observed with the Hamilton echelle spectrograph over more than a decade. One goal is to test magnetospheric accretion model predictions. Observational evidence previously published…

Intermediate resolution (R=7000) spectroscopy is presented for 76 photometrically selected very low mass (0.04<M<0.3M_{sun}) candidate members of the Sigma Orionis cluster. More than two thirds appear to be genuine cluster members on the…

The unusual properties of transition objects (young stars with an optically thin inner disc surrounded by an optically thick outer disc) suggest that significant disc evolution has occured in these systems. We explore the nature of these…

The YY Ori stars are T Tauri stars with prominent time-variable redshifted absorption components that flank certain emission lines. One of the brightest in this class is S CrA, a visual double star. We have obtained a series of…

The young cluster NGC 2264 was observed with the Corot satellite for 23 days uninterruptedly in March 2008 with unprecedent photometric accuracy. We present here the first results of the analysis of the accreting population. We intended to…

It has been asserted that the primary star in the HD 189733 system steadily accretes evaporated exospheric gases from its ``hot Jupiter'' companion, rather like a T Tauri star accreting from a disk. We conduct statistical and periodogram…

Binary star-formation theory predicts that close binaries (a<100 AU) will experience periodic pulsed accretion events as streams of material form at the inner edge of a circumbinary disk, cross a dynamically cleared gap, and feed…

We present photometry at 3-24um for all known members of the Upper Scorpius association (~11 Myr) based on all images of these objects obtained with the Spitzer Space Telescope and the Wide-field Infrared Survey Explorer. We have used these…

The inner 0.1 AU around accreting T Tauri stars hold clues to many physical processes that characterize the early evolution of solar-type stars. The accretion-ejection connection takes place at least in part in this compact magnetized…

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…

We have analyzed nearly all images of the Taurus star-forming region at 3.6-24um that were obtained during the cryogenic mission of the Spitzer Space Telescope (46 deg^2) and have measured photometry for all known members of the region that…

We present new X-ray and Far Ultraviolet (FUV) observations of T Tauri stars covering the age range 1 to 10 Myr. Our goals are to observationally constrain the intensity of radiation fields responsible for evaporating gas from the…

The proliferation of high time-resolution and decades-long monitoring of classical T Tauri stars provides a vast opportunity to test the variability of the star-disk connections. However, most monitoring surveys use single broad-band…

We present results from a low resolution (R~300) near-infrared spectroscopic variability survey of actively accreting T Tauri stars (TTS) in the Taurus-Auriga star forming region. Paschen and Brackett series H I recombination lines were…