Non-grey dimming events of KIC 8462852 from GTC spectrophotometry

Abstract

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 Ångström absorption coefficient of $2.19\pm 0.45$, 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. During occultation events, these particles must be replenished on time-scales of days. If dust is indeed the source of KIC 8462852's dimming events, deeper dimming events should show more neutral colours, as is expected from optically thick absorbers.

5 pages, accepted for A&A letters

References in corpus (6)

• Families of Plausible Solutions to the Puzzle of Boyajian's Star
• The First Post-Kepler Brightness Dips of KIC 8462852
• KIC 8462852 Faded Throughout the Kepler Mission
• Modelling the KIC8462852 light curves: compatibility of the dips and secular dimming with an exocomet interpretation
• Extinction and the Dimming of KIC 8462852
• The GALEX View of "Boyajian's Star" (KIC 8462852)

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• The Breakthrough Listen Search for Intelligent Life: Searching Boyajian's Star for Laser Line Emission
• A Large Ground-Based Observing Campaign of the Disintegrating Planet K2-22b
• The KIC 8462852 Light Curve From 2015.75 to 2018.18 Shows a Variable Secular Decline
• Sudden extreme obscuration of a Sun-like main-sequence star: evolution of the circumstellar dust around ASASSN-21qj
• Non-gray, Month-long Brightening of KIC 8462852 in the Immediate Aftermath of a Deep Dip
• High-resolution spectroscopy of Boyajian's star during optical dimming events
• Extrasolar enigmas: from disintegrating exoplanets to exoasteroids