Gaia will provide accurate parallaxes, spectrophotometry and spectroscopy for hundreds of thousands of emission-line stars across the whole HR diagram. In preparation for the Gaia mission, we are developing algorithms to recognize and classify emission-line stars. A large collection of ground-based spectroscopic observations has been collected and will be used for testing and training the algorithms.
Gaia will also provide information on several millions of early-type stars. Determining accurate parameters for these stars from Gaia data only will be difficult due to the AV – Teff degeneracy.