We report high-resolution spectroscopic observations for a sample of 38 T Tauri stars (TTS), complemented by UBVRI photometry of 13 TTS, and CCD VRI photometry for 2 visual binaries. Based on these observations and data taken from the literature, we derive lithium abundances in 53 TTS, concentrating on weak-line TTS (WTTS). The sample spans the

We present results from five nights of pseudo-simulations JHK infrared monitoring of the blazar OJ 287 taken with the Carlos Sanchez Telescope during March 1991 with a time resolution of approximately 20 min. The monitoring shows small amplitude variations in time scales of a few tens of minutes, which are largest in J. Considerable variations are

IAUC 5929 available at Central Bureau for Astronomical Telegrams. IAUC 5929 available at Central Bureau for Astronomical Telegrams.

The back-reaction of an incompressible two-dimensional flow of constant strain to the accelerated motion of a straight cylinder is calculated in the general case that the flow is inhomogeneous, nonstationary, and with nonvanishing (although constant) vorticity. The resulting enhanced inertia of the cylinder is basically given by its relative

The subject of this study is the pre-main sequence (PMS) evolution of stars less massive than ~1.2 solar mass, using lithium as the main tool for confronting model predictions with observations. In addition, it is proposed to use Li as a test of the possible substellar nature of brown dwarf candidates. The main results of this work are: 1.) The

By integrating the differential equation system of the single-body meteor theory which describes meteor flight in the atmosphere, we show that the population index r depends on the radiant zenithal distance zR. When zR is large, r diminishes, requiring correction in order to obtain reliable number density profiles. A new method is proposed to