We present high angular resolution observations with the Keck Interferometer, high-dispersion spectroscopic observations with Keck/NIRSPEC, and near-IR photometric observations from PAIRITEL of a sample of 11 solartype T Tauri stars in nine systems.We use these observations to probe the circumstellar material within 1 AU of these young stars, measuring the circumstellar-to-stellar flux ratios a...

Aims. In order to better model massive B-type stars, we need to understand the physical processes taking place in slowly pulsating B (SPB) stars, chemically peculiar Bp stars, and non-pulsating normal B stars co-existing in the same part of the H-R diagram. Methods. We carry out a comparative study between samples of confirmed and well-studied SPB stars and a sample of well-studied Bp stars wit...

Aims. We present asteroseismological inferences on RXJ2117.1+3412, the hottest known pulsating PG1159 star. Our results are based on full PG1159 evolutionary models recently presented by Miller Bertolami & Althaus (2006). Methods. We performed extensive computations of adiabatic g-mode pulsation periods on PG1159 evolutionary models with stellar masses ranging from 0.530 to 0.741M⊙. PG1159 stel...

Aims. We present asteroseismological inferences on RXJ2117.1+3412, the hottest known pulsating PG1159 star. Our results are based on full PG1159 evolutionary models recently presented by Miller Bertolami & Althaus (2006). Methods. We performed extensive computations of adiabatic g-mode pulsation periods on PG1159 evolutionary models with stellar masses ranging from 0.530 to 0.741M⊙. PG1159 stel...

HST UV spectra were obtained to study whether the φ Leo system has one or more stellar companions, as shown for A-star dwarf, HR10, pulsation, transiting exocomets. During five partial observation sets spread over 13 months, redshifted gas with radial velocities up +245 km s−1 was observed on occasion, lower velocity infalling material seen twice. Blueshifted features high −150 three in two als...

The linear adiabatic pulsation-periods of Mira variable stars have been derived. Approximately 2701[1]models were calculated for M = 0.7 MΘ to 2 MΘ stars with radii from 180 RΘ to 340 RΘ and luminosities from 2800 LΘ to 10,000 LΘ. The chemical composition of all models is (X,Z) = (0.7,0.02). From the result of this study, linear relations on Luminosity-Period-Mass relationship and luminosity-pe...