ES-03-0032

Disc Population of Free-Floating Planets in Taurus

Tommy Rodrigues, Herve Bouy, Motohide Tamura, Javier Olivares Romero, Nu?ria Miret-Roig, David Barrado, Phillip Galli, Nuria Huelamo, Emmanuel Bertin, Jean-Charles Cuillandre

Free-floating planets (FFPs) are planetary-mass objects that do not orbit a star but roam the galaxy isolated. The origin and the formation of these exotic objects is still largely an open question.

Similar to slightly more massive brown dwarfs, four main scenarios are considered to explain their existence: a) within a proto-planetary disc followed by ejection by dynamical scattering between planets; b) isolated, in a similar way to stars from the collapse and contraction of a tiny molecular clump; c) as aborted stellar embryos ejected from a stellar nursery before the hydrostatic cores could build up enough mass to become a star; d) through the photo-erosion of a pre-stellar core by stellar winds from a nearby OB star before it can accrete enough mass to become a star.

A major key diagnostic of FFP formation and evolution is the occurrence and properties of discs. The presence of discs around sub-stellar objects was initially thought to favor a star-like formation mechanism. However, the three main formation mechanisms proposed to date are expected to produce discs around sub-stellar and planetary mass objects, albeit with different disc fractions and properties. The distributions of disc size and mass are therefore fundamental to test the predictions of the various mechanisms.

In this poster, we present the gathering of a new sample of FFPs/low mass objects with disks candidates in the Taurus star-forming region. This sample corresponds to the objects that we could identify displaying an mid-IR excess (WISE and Sptizer photometry) in the spectral energy distribution. We aim to characterize the disc population (size and mass) in Taurus around FFPs in the future and thus constrain the theories.

[Poster PDF File]