Starless Cores as Fundamental Physics Labs

Abstract

We present high resolution observations in the starless dense molecular core L1512 performed with the Medicina 32m radio telescope. The resolved hfs components of HC3N and NH3 show no kinematic sub-structure and consist of an apparently symmetric peak profile without broadened line wings or self-absorption features suggesting that they sample the same material. The velocity dispersion is 101( ± 1) m s − 1for NH3 and 85( ± 2) m s − 1 for HC3N. The kinetic temperature of the cloud is estimated at 9.2 ( ± 1.2) K and the turbulence is of 76 m s − 1in a subsonic regime. This places L1512 among the most quiescent dark cores and makes it an ideal laboratory to study variations of the electron-to-proton mass ratio, $\mu = {m}_{\mathrm{e}}/{m}_{\mathrm{p}}$ by means of observations of inversion lines of NH3 combined with rotational lines of other molecular species.