Institute of Astronomy

Approaching the origin of warm components in resolved cold debris discs

SpeakerTalk DateTalk Series
Torsten Loehne28 July 2014Across HR 2014 Posters


Observations at optical and far-infrared wavelengths reveal the presence of debris discs around at least 20 percent of stars across the main sequence. For a growing number of observed systems with debris discs, spatial resolution and densely sampled SEDs allow us to more tightly constrain their properties. Being remnants of the planet formation process, debris discs consist of (unobservable) planetesimals and collisionally replenished dust. To link observational data with potential scenarios for their formation and dynamical history, we performed in-depth collisional modeling for a handful of discs (e.g., HD 207129, HIP 17439, q1 Eri). The simulations start from a distribution of planetesimals and follow the production and loss of material in a collisional cascade, including the dynamical effects of direct radiation pressure and drag forces. One characteristic feature common to the discs is the presence of additional emission closer to the star, incompatible with a pure ring-like disc. We show that this emission can be explained, to a varying degree, by (a) drag of dust into an inner region devoid of planetesimals, (b) an extended, self-stirred and self-cleared debris disc, and/or (c) a separate inner disc. In all cases, the models suggest low dynamical excitation, i.e. discs that are quiescent rather than very active.