| Abstract | dc.description.abstract | Astrometric measurements for 25 red dwarf systems are presented, including the Þrst deÞnitive trigonometric parallaxes
for 20 systems within 10 pc of the Sun, the horizon of the RECONS sample. The three nearest systems that
had no previous trigonometric parallaxes (other than perhaps rough preliminary efforts) are SO 0253+1652 (3:84
0:04 pc, the 23rd nearest system), SCR 1845 6357 AB (3:85 0:02 pc, 24th nearest), and LHS 1723 (5:32
0:04 pc, 56th nearest). In total, seven of the systems reported here rank among the nearest 100 stellar systems. Supporting
photometric and spectroscopic observations have been made to provide full characterization of the systems,
including complete VRIJHKs photometry and spectral types. A study of the variability of 27 targets reveals six obvious
variable stars, including GJ 1207, for which we observed a ßare event in the V band that caused it to brighten by
1.7 mag. Improved parallaxes for GJ 54 AB and GJ 1061, both important members of the 10 pc sample, are also
reported.DeÞnitive parallaxes forGJ 1001A,GJ 633, andGJ 2130 ABC, all ofwhich have been reported to bewithin
10 pc, indicate that they are beyond 10 pc. Fromthe analysis of systems with (previously) high trigonometric parallax
errors, we conclude that parallaxes with errors in excess of 10 mas are insufficiently reliable for inclusion in the
RECONS sample. The cumulative total of new additions to the 10 pc sample since 2000 is now 34 systems: 28 by the
RECONS team and six by other groups. This total represents a net increase of 16% in the number of stellar systems
reliably known to be nearer than 10 pc. | en |
