Non-grey dimming events of KIC 8462852 from GTC spectrophotometry

Understand

We report ground-based spectrophotometry of KIC 8462852, during its first dimming events since the end of the Kepler mission.

• The dimmings show a clear colour-signature, and are deeper in visual blue wavelengths than in red ones.
• The flux loss' wavelength dependency can be described with an \AA ngstr\"om absorption coefficient of $2.19\pm0.45$, which is compatible with absorption by optically thin dust with particle sizes on the order of 0.0015 to 0.15 $\mu$m.
• These particles would be smaller than is required to be resistant against blow-out by radiation pressure when close to the star.