Panchromatic study of the extremely dense prestellar core on the verge of first core formation

Naomi Hirano  (ASIAA)

The prestellar core G208.68-19.02-N2 (G208-N2) in the Orion Molecular Cloud 3 (OMC3) has been studied with the ALMA in Band 4 (2 mm), 6 (1.3 mm and 1.1 mm), 7 (0.83 mm, ACA), 8 (0.75 mm), 9 (0.45 mm), and 10 (0.35 mm). The dust continuum emission revealed a filamentary structure with a length of ~5000 au and an average H2 volume density of ~6 x 10^7 cm^-3. At the tip of this filamentary structure, there is a compact  "nucleus" with a radius of ~150--200 au and a mass of ~0.1 M_sun. The nucleus does not have a counterpart at wavelength shorter than 0.35 mm. In addition, there is no sign of CO outflow localized to this nucleus. The spatial distributions of the molecular lines reveal significant chemical segregation in G208-N2. Although N2D+ and H2D+ trace the filamentary structure, they do not exhibit pronounced peak toward the nucleus. Instead, the emission peaks of DCO+, H2CO, and CH3OH appear in the vicinity of the nucleus. In this talk, we will discuss the possible evolutionary stage, i.e. prestellar of first hydrostatic core, of this enigmatic object.