Transiting planets of intermediate-mass stars
Final Report Abstract
In contrast to planets of solar-like stars, very little is known about planets of intermediate mass (1.3-2.1 Msun) stars. The interesting aspect is that the lifetime of their disks is half as long as that of lower-mass stars. Thus, if we detect close-in planets of such stars, we know that these planets must have formed and migrated inwards within a short time. This is a crucial test for theories of planet formation. The CoRoT-survey is ideal for this purpose, because (1.) 15.9% of the targets that are being observed are main-sequence A-type stars (other space-based surveys do not observe A-stars), because (2.) CoRoT monitors the fields for 150 days so that stellar spots and oscillations are not a source of false-positives and, because (3.) for all our targets light-curves in three colours have been obtained, which allowed us to discriminate efficiently against eclipsing binaries. For our study, we selected the 10 most prominent candidates to be observed with CAFE, the fibre-fed and stabilized spectrograph at the 2.2m-telescope of the Calar Alto observatory. After combing the data obtained with data taken at other telescopes, we discovered the first transiting brown dwarf that is orbiting an A-star. This discovery of a brown dwarf with an orbital period of only a few days is particularly interesting, because it shows that A-star can have brown dwarf companions with short orbital periods. Such objects do not exist, or are at least very rare for solar-like stars.
