plural of helium

(uncountable) The second lightest chemical element (symbol He) with an atomic number of 2 and atomic weight of 4.002602, a colorless, odorless and inert noble gas.

plural of helium variable

plural of helium star

(physics) nuclear fusion involving helium nuclei.

(physics, astronomy) the nucleosynthesis process, in stars with temperatures over 10⁸K, in which helium is converted to carbon and then to oxygen, neon and magnesium

(astronomy) The sudden beginning of the burning of helium in the core of stars of intermediate mass or on the surface of an accreting white dwarf.

Speech whose timbre (but not pitch) has been affected by the inhalation of helium, due to the difference in the speed of sound in that gas, compared with air.

(archaeology) a method of determining the age of rock that depends on the production of helium during the decay of various radioactive isotopes of uranium and thorium.

(physics) The liquified form of helium that does not solidify even at absolute zero; it shows unusual properties, such as superfluidity, due to quantum effects.