alpha element

An alpha element (or alpha species) is any of the elements that can be created by the alpha process, the combination of a nucleus and an alpha particle (alpha capture), which are several elements with even atomic numbers, 10 and larger. Some of the same elements are often created by other processes, e.g., carbon burning. Commonly, alpha elements are taken as a separate group from iron peak elements, those with atomic numbers near that of iron; though even-numbered iron peak elements can be generated by the alpha process, they are commonly not termed alpha elements. Elements generally termed alpha elements:

The term is often used regarding the metallicity within a region of space (e.g., in a galaxy's stars and interstellar medium): the ratio of alpha elements to iron peak elements suggests the general type of supernova that produced and spread the elements, which reveals something of the star formation history of the region. The term alpha-enhanced is often used to describe something with such a ratio indicating a greater amount of alpha elements than usual.