ANGULAR DIAMETERS OF THE CARBON STARS UU-AURIGAE, Y-CANUM-VENATICORUM, AND TX-PISCIUM FROM OPTICAL LONG-BASE-LINE INTERFEROMETRY

The angular diameters of the three carbon stars UU Aur, YCVn, and TX P sc have been determined with the MkIII Optical Interferometer. Measure ments of UU Aur at lambdalambda = 712, 754, and 800 nm agree well with each other; the weighted mean for the uniform disk diameter is theta( UD) = 11.28 +/- 0.21 mas. For Y CVn, theta(UD) = 13.81 +/- 0.43 mas is obtained at 800 nm. There are indications of temporal variations of t he diameter of TX Psc; values between 9.4 and 11.1 mas were measured f or this star. Effective temperatures are calculated for these three st ars and for six other carbon stars for which diameters measured with t he lunar occultation technique have been published. These fundamentall y determined effective temperatures correlate well with, but are on av erage about 100 K cooler than, effective temperatures for the same sta rs obtained with the infrared flux method by Tsuji (1981). Color tempe ratures determined by Baumert (1972) and by Gow (1977) correlate poorl y with effective temperatures.