Signatures of planets and protoplanets in the Galactic center: a clue to
  understand the G2 cloud?
  Several hundred young stars lie in the innermost parsec of our Galaxy. The
super-massive black hole (SMBH) might capture planets orbiting these stars, and
bring them onto nearly radial orbits. The same fate might occur to planetary
embryos (PEs), i.e. protoplanets born from gravitational instabilities in
protoplanetary disks. In this paper, we investigate the emission properties of
rogue planets and PEs in the Galactic center. In particular, we study the
effects of photoevaporation, caused by the ultraviolet background. Rogue
planets can hardly be detected by current or forthcoming facilities, unless
they are tidally disrupted and accrete onto the SMBH. In contrast,
photoevaporation of PEs (especially if the PE is being tidally stripped) might
lead to a recombination rate as high as ~10^45 s^-1, corresponding to a
Brackett-gamma luminosity ~10^31 erg s^-1, very similar to the observed
luminosity of the dusty object G2. We critically discuss the possibility that
G2 is a rogue PE, and the major uncertainties of this model.
