On the post-T-Tauri nature of late-type visual companions to B-type stars

Martin, E. L.; Magazzu, A.; Rebolo, R.
Referencia bibliográfica

Astronomy and Astrophysics (ISSN 0004-6361), vol. 257, no. 1, p. 186-198.

Fecha de publicación:
Número de autores
Número de autores del IAC
Número de citas
Número de citas referidas
We report on intermediate-to-high resolution spectroscopy and standard broadband photometry of late-type visual companions to early-type stars. Our program stars are drawn from the sample of post-T-Tauri candidates studied by Lindroos (1986). Measurement of radial velocities and derivation of the surface abundances of lithium and heavier elements (Ca, Fe, Si, and Ti) allow us to identify genuine post-T Tauris (PTTS) with a high degree of confidence. Only 5 out of the 14 stars studied by us can be unambiguously classified as premain-sequence objects. On the Hertzsprung-Russell diagram all five lie closer to the ZAMS than classical T Tauris do. The PTTS are located on the radiative part of premain-sequence evolution tracks of stars with mass around 1 solar mass, overlapping with some stars of the so-called naked T Tauri population. We discuss the general properties of PTTS, which are similar to those of NTTS. The metallicity of PTTS is close to solar, as expected for Population I stars. The abundance of lithium in PTTS with masses higher than 1 solar mass is found to be cosmic, while in PTTS with masses 0.9-0.8 solar mass lithium is depleted by about one order of magnitude.