No Death Star--For Now

Abstract

A star passing within ~10⁴ AU of the Sun would trigger a comet shower that would reach the inner solar system about 0.18 Myr later. We calculate an a priori probability of ~0.4% that a star has passed this close to the Sun but that the comet shower has not yet reached the Earth. We search the Hipparcos catalogue for such recent close-encounter candidates and, in agreement with García-Sánchez et al., find none. The new result reported in this Letter is an estimation of the completeness of the search. Because of the relatively bright completeness limit of the catalogue itself, V~8, the search is sensitive to only about half the stars that could have had such a near encounter. On the other hand, we show that the search is sensitive to nearly all of the past encounters that would lead to a major shower in the future and conclude that it is highly unlikely that one will occur during the next 0.5 Myr.