• Kirchschlager, Florian

Abstract

For the first time we observed the emission of hot exozodiacal dust in L band. We used the new instrument MATISSE at the VLTI to detect the hot dust around ? Tuc at wavelengths between 3.37 ?m and 3.85 ?m. The dust-to-star flux ratio in L band amounts to 5 to 7 % and the spectral slope is ? = 3.92. We modelled the spectral energy distribution based on the new L band data alone and in combination with H band data (VLTI/PIONIER) published previously. In all cases we find 0.58 ?m grains of amorphous carbon to fit the ? Tuc observations the best, however, also nanometre or micrometre grains and other carbons or silicates reproduce the observations well. Since the H band data revealed a temporal variability, while our L band data were taken at a different epoch, we combine them in different ways. Depending on the approach, the best fits are obtained for a narrow dust ring at a stellar distance in the 0.1 au to 0.29 au range and thus with a temperature between 940 K and 1430 K.

Topics

• impedance spectroscopy
• amorphous
• Carbon
• grain