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Up: A spectroscopic survey

1. Introduction

For many years the nature of the tex2html_wrap_inline1148Bootis stars has been controversial. About 20% of all PopulationI A-type stars show abundance peculiarities. Most of these CP stars are characterized by strong overabundances of iron peak elements (Jaschek & Jaschek 1995). In contrast, the tex2html_wrap_inline1148Bootis stars are metal poor, Populaton I, A and early F-type stars. Unfortunately, these astrophysically interesting stars are quite rare; the most recent list of confirmed members (Gray & Corbally 1993) had only 20 members. A recent paper (Paunzen et al. 1997) attempted to expand this number by a critical assessment of the literature resulting in a total of 45 members and candidate members. This small sample of stars still makes a sound statistical analysis difficult. Therefore we have started a spectroscopic survey for new members in the galactic field, open clusters and associations. The discovery of tex2html_wrap_inline1148Bootis stars in open clusters and associations is especially important because of the possibility of age determination, thus providing the means to distinguish between the two proposed theories - the diffusion/mass loss theory (Michaud & Charland 1986) and the accretion theory (Venn & Lambert 1990). Candidate tex2html_wrap_inline1148Bootis stars were discovered in the Orion OB1 association (three new tex2html_wrap_inline1148Bootis stars found), NGC2264 (two candidates) and the galactic field (five new tex2html_wrap_inline1148Bootis stars). Additional observations in NGC2232 (age tex2html_wrap_inline1200; Mermilliod 1981) and NGC2301 (agetex2html_wrap_inline1202108yr; Mermilliod 1981) yielded a null result. We have been able to confirm a number of the candidate members proposed in Paunzen et al. (1997).



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