Spectroscopic distances of 28 nearby star candidates

TL;DR

This study spectroscopically analyzed 28 candidate nearby stars to verify their classifications and improve distance estimates, identifying 11 within 25 parsecs and clarifying the nature of some common proper motion pairs.

Contribution

The paper provides improved spectroscopic distance estimates for neglected nearby star candidates, refining their classification and confirming some as within 25 parsecs.

Findings

11 stars confirmed within 25 parsecs

Reclassification of LDS 1365's components as unrelated

Good agreement with Hipparcos distances for some pairs

Abstract

28 hitherto neglected candidates for the Catalogue of Nearby Stars (CNS) were investigated to verify their classification and to improve their distance estimates. All targets had at least a preliminary status of being nearby dwarf stars based on their large proper motions and relatively faint magnitudes. Better photometric and/or spectroscopic distances were required for selecting stars which are worth the effort of trigonometric parallax measurements. Low-resolution spectra were obtained with NASPEC at the Tautenburg 2m telescope and with CAFOS at the Calar Alto 2.2m telescope. The spectral types of M-type stars were determined by direct comparison of the target's spectra with those of comparison stars of known spectral types observed with the same instrument. The classification of earlier types was done based on comparison with published spectral libraries. The majority were classified as M dwarfs including 11 stars within 25 pc. The fainter component of LDS 1365, previously thought to form a nearby common proper motion pair, is according to our results an unrelated high-velocity background star. For several other nearby common proper motion pairs our distance estimates of the fainter components are in good agreement with Hipparcos distances of the brighter components. (abridged)