We examine the implications of a beat frequency modulatedmodel of T Tauri accretion. In particular we show that measurements of the variability of accretion generated lines can be used in conjunction with existing photometry to obtain a measurement of the underlying photospheric and disc ux. This provides an independent way of checking spectral energy distribution modelling. In addition, we sho...

Recent analysis of high resolution Chandra X-ray spectra has shown that the Ne/O abundance ratio is remarkably constant in stellar coronae. Based on this result, we point out the utility of the Ne/O ratio as a discriminant for accretionrelated X-rays from T Tauri stars, and for probing the measure of grain-depletion of the accreting material in the inner disk. We apply the Ne/O diagnostic to th...

We have studied numerically the evolution of protostellar disks around intermediate and upper mass T Tauri stars (0.25 M⊙ < M∗ < 3.0 M⊙) that have formed self-consistently from the collapse of molecular cloud cores. In the T Tauri phase, disks settle into a self-regulated state, with low-amplitude nonaxisymmetric density perturbations persisting for at least several million years. Our main find...

We present mid-infrared spectra of T Tauri stars in the Taurus star-forming region obtained with the Spitzer Infrared Spectrograph (IRS). For the first time, the 5–36 μm spectra of a large sample of T Tauri stars belonging to the same star-forming region is studied, revealing details of the midinfrared excess due to dust in circumstellar disks. We analyze common features and differences in the ...

Discovery of seven T Tauri stars and a brown dwarf candidate in the nearby TW Hydrae Association. Abstract We report the discovery of five T Tauri star systems , two of which are resolved binaries, in the vicinity of the nearest known region of recent star formation , the TW Hydrae Association. The newly discovered systems display the same signatures of youth (namely high X-ray flux, large Li a...

Background: Casein Kinase 1 (CK1) is one of few proteins known to affect cellular timekeeping across metazoans, and the naturally occurring CK1 mutation shortens circadian period in mammals. Functional conservation of a timekeeping function for CK1 in the green lineage was recently identified in the green marine unicell Ostreococcus tauri, in spite of the absence of CK1's transcriptional target...

We present the ROSAT PSPC pointed and ROSAT All-Sky Survey (RASS) observations and the results of our low and high spectral resolution optical follow-up observations of the T Tauri stars (TTS) and X-ray selected T Tauri star candidates in the region of the high galactic latitude dark cloud MBM12 (L1453-L1454, L1457, L1458). Previous observations have revealed 3 “classical” T Tauri stars and 1 “...