Extrasolar Kuiper and asteroid belts Modelling far-infrared dust emission

Licentiatavhandling, 2014

The first detections of circumstellar dust emission were announced in the mid 1980s. Direct observations of the edge-on disc of beta Pictoris provided evidence that the dust was part of possible planetary systems. About a decade later, in 1995, the first confirmed extrasolar planet around a main sequence star (51 Pegasi b) was announced. The aims here are to study the dynamics and evolution of planetary systems, in which both dust and planets are connected. The aim is also to put the solar system, with its combination of small and large planets, and rings of planetesimals, into a wider context by comparing it with other systems. To do this we must map out planetary systems around solar-like stars in the solar neighbourhood, through observations and precise modelling. The nearest solar-like neighbour is alpha Centauri. This is a binary star with possibilities for planets. We have been able to set upper limits on circumstellar dust emission for these stars to fractional luminosities of a few 10^−5. We have also used the primary star, alpha Centauri A, as a template to better understand how the far-infrared spectrum of solar-like stars behaves. In particular we look at how the chromospheric temperature inversion in the stellar atmosphere will affect dust emission estimates of other stars. We found with the spectrum of alpha Cen A, that a lack of detection of a temperature minimum in other stars could in reality account for dust emission with a fractional luminosity of 2*10^−7. We are continuing the work on three additional nearby solar-like stars, where one is a binary star with a giant planet. All of these stars already have confirmed dust emission, but may require additional modelling. This is an ongoing project and the results are pending.