Red giant brightness so common on both types of stars. Red giants are evolved from main-sequence stars with masses in the range from about to around . When a star initially forms from a collapsing molecular cloud in the interstellar medium, it contains primarily hydrogen and helium, with trace amounts of "metals" (in stellar structure, this simply refers to "any" element that is not hydrogen or helium i.e. atomic number greater than 2). These elements are all uniformly mixed throughout the star. The star reaches the main sequence when the core reaches a temperature high enough to begin fusing hydrogen (a few
Hydrogen gas porosity concentration in the gas is measured and converted into a reading of the gas concentration in the metal. This method is fast, reproducible and accurate, and can be used “on-line” on the cast shop floor. The amount of H in the gas loop of the instrument is determined by a thermal conductivity sensor, which provides high reproducibility and a broad measurement range. Hydrogen gas porosity Hydrogen gas porosity is an aluminium casting defect under the form of a porosity or void in an aluminium casting caused by a high level of hydrogen gas (H) dissolved in the aluminium at liquid