SIMBAD references

As part of our continuing search for peculiar A-type stars, especially λ Bootis stars, in open clusters of all ages, we have obtained classification spectra of 130 late B, A, and early F-type stars in 12 intermediate-age open clusters, including NGC 1039, 2281, 2548, 6633, 7039, 7063, 7092, and 7209, IC 4665, IC 4756, Stock 2, and Praesepe. The spectra were obtained with resolutions of 1.8 and 3.6 Å on the 0.8 m telescope of Appalachian State University and were classified on the MK system. Numerous classical Ap and Am stars were found among the 130, including two new Ap stars in NGC 7092. In addition, three emission-line stars and two candidate λ Bootis stars were found. Neither of these λ Bootis candidates turned out to be members of their respective clusters. Combined with 184 stars previously classified in 10 other intermediate-age open clusters, also devoid of λ Bootis stars, a statistically significant null result is obtained. We discuss the implications of this null result for our understanding of the λ Bootis mechanism.