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Speckle interferometry of HIPPARCOS link stars. II
A second list is presented of stars that have been tested for theirsuitability as astrometric links between the Hipparcos satellite and theSpace Telescope. A speckle interferometer and autocorrelator were used,first on the 1.9-m telescope of the Mt. Stromlo and Siding SpringObservatories, and then, after discarding 16 stars showing evidence of abinary nature, on the Anglo-Australian 3.9-m telescope. Results aregiven for 123 stars. Combining the present list with the 1984 list, itis estimated that 29 percent of the original selection of 'cleanlooking' stars (on sky survey prints) are expected to be multiple at theresolution of the 3.9-m telescope, 0.03-0.7 arcsec.
| A sample of solar-type stars of known age
A sample of field F and G dwarfs of known ages is presented. All thedwarfs are secondaries of visual binaries in which the temperature andgravity of the hotter primary has been estimated from Stromgrenphotometry, and its age derived from reference to isochrones. This ageis taken to apply to the secondary. Even in the case of F-typesecondaries, which themselves have measured Stromgren indices, it ismuch better to estimate ages from the primaries as it is demonstratedthat use of isochrones to determine age of stars not far evolved fromthe main sequence can lead to significant systematic overestimates ofages when the photometric measurements have typical random errors. Anumber of systems in which photometry is available for both componentshave primaries which appear much younger than the secondaries,suggesting a need for further investigation.
| UVBY Bet study of A-and F-type visual binaries. II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978AJ.....83.1646M&db_key=AST
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