COMMISSION 45: SPECTRAL CLASSIFICATION

Extract

This report gives an update on developments since the last General Assembly in Rio de Janeiro. Classification – both photometric and spectral – continues to play a vital role in stellar astrophysics and stellar surveys. During the past three years, rapid progress has been made in the classification of brown dwarfs, with the discovery of the first Y dwarfs and the introduction of a near-IR classification system for M- and L-dwarfs. The number of known L-dwarfs now exceeds 1000, and so peculiar types are beginning to show up. For instance, there is now enough material to define a low-gravity spectral sequence for the L0 – L5 dwarfs. In addition, a number of unusally blue L-dwarfs are now known. Large-area surveys, always of interest to Commission 45, have proliferated during this period, including RAVE, SEGUE, and WISE with many more in the planning stages.