O6

O6 may refer to several concepts in science and mathematics, depending on the context.

In astronomy, O6 denotes a subclass of O-type stars, which are among the hottest and most luminous in the universe. O-type stars have surface temperatures roughly in the range of 30,000 to 50,000 kelvin. The subclass O6 places the star in the middle of the O-range, indicating specific spectral features and a temperature around the mid-30,000s kelvin. O6 stars are blue-white and typically very massive, often tens of solar masses, with short lifespans. They play a key role in ionizing surrounding nebulae and shaping their environments through strong stellar winds and radiation.

In mathematics, O(6) denotes the orthogonal group in six dimensions. It consists of all real 6×6 matrices A that satisfy A^T A = I, representing linear transformations that preserve Euclidean length. The group includes both rotations and reflections and has two connected components corresponding to determinant ±1. The dimension of O(6) as a Lie group is 15. Its orientation-preserving subgroup is SO(6), the special orthogonal group, which has determinant +1. The Lie algebra so(6) also has dimension 15 and is, in a notable fact, isomorphic to su(4). O(6) appears in geometry, linear algebra, and theoretical physics as a symmetry group in six-dimensional space.

Other uses of the term O6 are context-dependent. It can appear as a model designation or shorthand in various fields, but there is no single universal definition beyond the principal meanings in astronomy and mathematics.