Abstract. From a sample of 50 T Tauri stars, mostly from the Taurus-Auriga complex, Paβ line profiles were obtained for 49 of the stars and Brγ profiles for 37 of the stars. Emission at Paβ was observed for 42 stars and emission at Brγ was found for 30 stars. The most conspicuous features in the line profiles is the almost complete absence of blueshifted absorption components and the relatively high frequency of inverse P Cygni profiles (IPC). At Paβ, 34% of the profiles are IPC while at Brγ 20% are IPC. The redshifted absorption features indicate infall at velocities of about 200 km s −1 , compatible with free fall from a few radii out. In general, line profiles are broad centrally peaked with slightly blueshifted line peaks. Existing wind and accretion models fail, in quantitative terms, to explain the shape of the observed profiles. Magnetospheric accretion models, being the currently preferred ones, produce lines too narrow (by ∼ 100 km s −1 FWHM), wings extending to velocities too low (by at least ∼ 100 km s −1 ) and with maximum normalized intensities too high by factors of a few. A qualitative agreement between some of the accretion model predicted profiles and some observations hint that emission in these lines might, at least partially, arise from infalling material. Definite claims regarding the origin of the emission in these lines cannot be made until models match observations much better than they currently do.

Abstract. We present the results of multisite observations spanning two years on the pre-main-sequence (PMS) star V351 Ori. A total of around 180 hours of observations over 29 nights have been collected, allowing us to measure five different periodicities, most likely related to the δ Scuti variability of V351 Ori. Comparison with the predictions of linear nonadiabatic radial pulsation models put stringent constraints on the stellar parameters and indicate that the distance to V351 Ori is intermediate between the lower limit measured by Hipparcos (210 pc) and that of the Orion Nebula (450 pc). However, radial pulsation models are unable to reproduce all of the observed frequencies with a single choice of (M * , L * , and T eff ), suggesting the presence of additional nonradial modes.

We study the formation of the calcium II infrared triplet lines 8498 Å, 8542 Å and 8662 Å, in the accreting magnetospheric flows of Classical T Tauri stars (CTTS), and present a grid of models for a large range of magnetospheric conditions. We apply our models to the interpretation of multi epoch observations of the CTTS DI Cep. We find that these lines form in the magnetospheric infall and that the variability of the CaII triplet lines in DI Cep can be explained in the context of changes in the mass accretion rate/temperature of the accretion column gas.

Abstract.We report the discovery of periodicities in the light curve of the Pre-Main Sequence (PMS) Herbig Ae star V346 Ori. We interpret variations in the light curve of the star as the superposition of at least two periodic signals that result from δ Scuti-type stellar oscillations. The computation of linear non-adiabatic radial pulsation models for PMS stars reproduces these periods for a 1.55 M star with T eff = 7410 K and log L/L = 0.74 pulsating in the fundamental and in the second overtone. If our assumption of radial oscillations is indeed correct, the star's location on the HR diagram places it at a distance significantly smaller than that of the Orion star forming region, hence raising questions regarding the evolutionary status of V346 Ori. Observations with better time sampling and spanning a longer period of time are needed if the latter question is to be addressed fully.

No abstract