Abstract It is uncertain whether or not low-mass Population III stars ever existed. While limits on the number density of with M * ≈ 0.8 ⊙ have been derived, using Sloan Digital Sky Survey (SDSS) data, little known about occurrence at lower masses. In absence reliable parallaxes, spectra metal-poor main-sequence (MPMS) ≲ can easily be confused those cool white dwarfs. To resolve this ambiguity,...

We report trigonometric parallaxes for the sources NGC 7538 and Cep A, corresponding to distances of 2.65 −0.11 kpc and 0.70 +0.04 −0.04 kpc, respectively. The distance to NGC 7538 is considerably smaller than its kinematic distance and places it in the Perseus spiral arm. The distance to Cep A is also smaller than its kinematic distance and places it in the “Local” arm or spur. Combining the d...

We analyze twenty five nearby metal-rich G and late-F dwarfs in order to verify whether the spectroscopic equilibrium (LTE) of iron lines satisfy the observational constraints imposed by the Infrared Flux Method (angular diameters) and Hipparcos parallaxes. The atmospheric parameters derived from iron lines (assuming LTE and employing 1D Kurucz model atmospheres) do not satisfy simultaneously b...