Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 2K007

Sub-stellar Companions and Stellar Multiplicity in the Taurus Star-Forming Region - A High-Contrast Survey

Daemgen, Sebastian (Department of Astronomy & Astrophysics, University of Toronto, Canada)
Bonavita, Mariangela (Department of Astronomy & Astrophysics, University of Toronto, Canada & INAF, Osservatorio Padova, Italy)
Jayawardhana, Ray (Department of Astronomy & Astrophysics, University of Toronto, Canada)

In recent years the rapid improvement of high-contrast imaging instrumentation and techniques lead to the discovery of a number of wide sub-stellar companions to nearby young stars, down to planetary mass. Some of these objects have mass ratios with respect to their parent stars of only ~1%, and due also to their extreme separation are hard to explain in any formation paradigm suggested so far, whether based on core accretion or disk instabilities. Hence, these objects may represent an extreme outcome of their underlying formation mechanisms, regardless of which it is. Previous surveys in nearby star forming regions such as Upper-Sco and Sco-Cen are consistent with the existence of a continuous population of companions, which suggests that binary formation may extend all the way down to planetary masses for wide separations, or at least that mass alone is not a clear-cut observational diagnostic for distinguishing between formation mechanisms. Moreover, the same studies suggest a higher frequency of wide companions in young star forming regions, with respect to young moving groups or in the field, implying that ejection mechanisms could be relevant already within the first few Myrs after formation. In this poster we present initial results of a large, coherent survey for sub-stellar companions and stellar multiplicity of Taurus stars of all masses. It uses high-spatial resolution NIRI/Gemini North adaptive optics imaging in K-band, allowing us to detect companions as close as 0.07\" out to 12\" (corresponding to ~10AU-1500AU at the distance of Taurus) with masses down to ~1 MJup. The findings will be compared with those of deep high-spatial resolution studies of other young associations. Such a comparison gives insight to, e.g., the interplay between the low-mass multiplicity fraction and mass ratios or primary mass and age, respectively.

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