UCAC4 NEARBY STAR SURVEY: A SEARCH FOR OUR STELLAR NEIGHBORS

Abstract

We use data from the U.S. Naval Observatory fourth CCD Astrograph Catalog\n(UCAC4) in combination with photometry from the AAVSO Photometric All-Sky\nSurvey (APASS) and Two Micron All-Sky Survey (2MASS) to identify stars within\n25 pc of the Sun. A sample of nearby stars with accurate trigonometric\nparallaxes from the Research Consortium On Nearby Stars (RECONS) is used to\ngenerate a set of 16 new photometric color-$M_{K{_s}}$ relations that provide\ndistance estimates with uncertainties of 15\\%. This work expands the available\nsuites of well-calibrated photometric distance relations that can be used to\nidentify nearby stellar systems.\n The distance relations are used with quality cuts to extract an initial\nsample of stars from the UCAC4 estimated to be within 25 pc. Color, proper\nmotion and existing literature sources are then used to obtain a clean sample\nof red dwarfs, while limiting the amount of contamination from background\ngiants, resulting in a sample of 1761 candidate nearby stars within 25 pc. Of\nthese, 339 are new discoveries with no previously known published parallax or\ndistance estimate, primarily with proper motions less than 0.2 arcsec/year.\nFive stars are estimated to be within 10 pc, with the nearest, TYC 3980 1081 1\nwith V$=$ 10.50, estimated to be at 5.93 pc. That several hundred new stars\nhave been revealed so close to the Sun illustrates once again that there is\nconsiderable work yet to be done to map the solar neighborhood, and that\nadditional nearby stars are likely still to be discovered.\n