Many nearby main-sequence stars have been searched for debris using the far-infrared Herschel satellite, within the DEBRIS, DUNES and Guaranteed-Time Key Projects. We discuss here 11 stars of spectral types A to M where the stellar inclination is known and can be compared to that of the spatially-resolved dust belts. The discs are found to be well aligned with the stellar equators, as in the case of the Sun's Kuiper belt, and unlike many close-in planets seen in transit surveys. The ensemble of stars here can be fitted with a star-disc tilt of ~<10 degrees. These results suggest that proposed mechanisms for tilting the star or disc in fact operate rarely. A few systems also host imaged planets, whose orbits at tens of AU are aligned with the debris discs, contrary to what might be expected in models where external perturbers induce tilts.
@article{arxiv.1310.6936,
title = {Alignment in star-debris disc systems seen by Herschel},
author = {J. S. Greaves and G. M. Kennedy and N. Thureau and C. Eiroa and J. P. Marshall and J. Maldonado and B. C. Matthews and G. Olofsson and M. J. Barlow and A. Moro-Martin and B. Sibthorpe and O. Absil and D. R. Ardila and M. Booth and H. Broekhoven-Fiene and D. J. A. Brown and A. Collier Cameron and C. del Burgo and J. Di Francesco and G. Duchene and J. Eisloffel and S. Ertel and W. S. Holland and J. Horner and P. Kalas and J. J. Kavelaars and J. -F. Lestrade and L. Vican and D. J. Wilner and S. Wolf and M. C. Wyatt},
journal= {arXiv preprint arXiv:1310.6936},
year = {2015}
}