SIMBAD references

We have collected 51 high resolution echelle spectra of the classical T Tauri star BP Tauri during two observing periods. The spectra were sampled on time intervals ranging from 30 minutes to several days. Simultaneous UBV photometric observations were made during some of the observations. The Balmer lines from Hα to Hε, He I λ5876A, the Na I D doublet and Ca II λ3933, λ3968, λ8542, λ8662A were covered within the spectral orders. From the analyses of the line variability we have found that the Hα and Hβ emission show significant variations in both line strength and profile shape on time scales from about 2 hours to days. Also the lines of Ca II, Na I and He I are variable both between and during single nights in equivalent widths and/or in line profiles. The profiles of the Ca II emission lines show centrally peaked emission superimposed on a broader, slightly blue asymmetric, emission component that appeared on different occasions. The appearance of this feature coincided with the appearance of a red displaced feature in the Hα line. The absorption components of the Na I D doublet showed a change in their central positions from +40 to +140km/s within a few days. From the analysis of the time scales of the variations in different parts of the emission lines and of the correlation of the variability between different lines we conclude that the bulk of the line emission is produced in infalling gas. The night-to-night behaviour of the profiles strongly support the hypothesis that the accretion flow is channeled by an inclined magnetosphere. This scenario is also supported by the simultaneous photometric observations carried out. In addition, the symmetry of the extended Hα line wings, the blue asymmetry of the higher Balmer lines and the longer characteristic time scales of variability for the extended wings of the Hα and Hβ lines indicate that line emission from a stellar wind is present as well.