Blue stragglers in open clusters*
III. NGC 7789
Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: DeSchoenberner@aip.de
2 Department of Astronomy, Odessa State University, Shevchenko Park, 65014, Odessa, Ukraine
3 Isaac Newton Institute of Chile, Odessa Branch, Chile e-mail: firstname.lastname@example.org
4 Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana 70803, USA e-mail: Drilling@baton.phys.lsu.edu
S. M. Andrievsky
Accepted: 7 November 2000
We performed for the first time a detailed LTE spectroscopic study of a sample of blue straggler stars in the moderately old open cluster NGC 7789. For eight stars the parameters and abundances of several elements were determined. The cluster members show a remarkable surface magnesium deficiency which is quite unusual for late B - early A stars. Iron and titanium abundances are in agreement with other photometric and spectroscopic estimates of the NGC 7789 metallicity. All the confirmed blue stragglers have rather low projected rotational velocities (with one exception for K88, km s-1).
Key words: stars: open clusters and associations: individual: NGC 7789 / stars: blue stragglers / stars: abundances
Based on the spectra collected at Kitt Peak National Observatory, operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation, and at the German-Spanish Astronomical Center, Calar Alto, operated by the Max-Plank Institute for Astronomy, Heidelberg, jointly with the Spanish National Commission for Astronomy.
© ESO, 2001