Astrophys. J 797, 119 (2014)

Imagine trying to study Saturn while the sun is shining. Such is the problem facing researchers who are actively looking for exoplanets around distant stars, as those stars always outshine any orbiting planets or surrounding dust. Instead, sophisticated interferometry techniques must null out the light from the star. Bertrand Mennesson and his team used exactly this technique to analyse forty-seven stars, about half with cool dust and half without.

And not all dust is the same. Most of the known exoplanets lie in cool dust well away from their host stars, thus making them easier to find. The challenge now lies in finding smaller Earth-like exoplanets in the warm 'habitable' zone nearer to the central star, but this warm (room temperature) dust makes such planets more difficult to resolve. The study using the twin Keck telescopes is the first to show that many stars with cool dust also have an inner region of obscuring warm dust. Those with too much dust are to be avoided when trying to find new exoplanets. However, these are the very systems most likely to have Earth-like planets. It's a fine balance.