Abstract

Trigonometric parallaxes, proper motions and V J(RI) KC photometry are given for 25 stars (of which one is a zeroparallax control field) targeted by the Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI), a widely scoped program aimed at discovering and characterizing nearby stars. The trigonometric parallaxes and proper motions presented are the last that were obtained with the CTIO 1.5 m telescope, which targeted the fainter subset of the CTIOPI input list. First trigonometric parallaxes are given for 22 systems, of which one is within 10 pc (DENIS 0255-4700), and 10 of which are between 10 and 25 pc. At a distance of 4.97±0.10 pc, and with a spectral type of L7.5 V, DENIS 0255-4700 is now the closest known L dwarf. In addition, with M V = 24.44, it is the faintest dwarf with a measured absolute visual magnitude. We present preliminary trigonometric parallaxes for five additional systems worthy of follow-up, and VRIJHK S photometry and photometric distance estimates for four of them. We also give photometry and distance estimates for 21 other promising targets in our input list for which definitive trigonometric parallaxes were not possible; 13 are likely to be closer than 25 pc. We also present color-magnitude and color-color diagrams, which, in combination with theoretical isochrones from the literature, tangential velocities, and M R and M J, have aided to identify the general nature of each of our targets. We have in this way discovered one new (spectroscopically confirmed) subdwarf and two suspected extreme subdwarfs that could be among the most extreme cases of these objects. We have also identified several very low mass stars, a few of which could be brown dwarfs. This concludes the CTIOPI 1.5 m program, from which we have derived a total of 69 trigonometric parallaxes (55 definitive, 6 preliminary, and 8 calibration). © 2006. The American Astronomical Society. All rights reserved.