Hydrostatic Instability in Very High Temperature Stars

Can very massive stars avoid Pair-instability Supernovae ?

Very massive primordial stars (140 M < M < 260 M ) are supposed to end their lives as pair-instability supernovae. Such an event can be traced by a typical chemical signature in low metallicity stars, but at the present time, this signature is lacking in the extremely metal-poor stars we are able to observe. Does it mean that those very massive objects did not form, contrarily to the primordial...

Effects of hydrostatic pressure and temperature on the AlGaN/GaN High electron mobility transistors

In this paper, drain-source current, transconductance and cutoff frequency in AlGaN/GaN high electron mobility transistors have been investigated. In order to obtain parameters of exact AlGaN/GaN high electron mobility transistors such as electron density, the wave function, band gap, polarization charge, effective mass and dielectric constant, the hydrostatic pressure and temperature effects a...

High-resolution Spectra of Very Low-Mass Stars

We present the results of high-resolution (1-0.4 Å) optical spectroscopy of a sample of very low-mass stars. These data are used to examine the kinematics of the stars at the bottom of the hydrogen-burning main sequence. No evidence is found for a significant difference between the kinematics of the stars in our sample with I–K > 3.5 (MBol ∼ 12.8) and those of more massive M-dwarfs (MBol ≈ 7 − ...

Bias-Temperature Instability in the High-k/Metal Gate Stacks

Besides the negative-bias temperature (NBTI) effect that is seen in the conventional polysilicon on SiO 2 or SiON gate stack, the high-k/metal gate stack also exhibits positive-bias temperature instability (PBTI) which has an adverse impact on the operation of the n-MOSFET. Significant threshold-voltage V t shift but negligible transconductance g m degradation was observed after PBTI stress. On...

Tritium transport in very high temperature reactors for hydrogen production