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Astron. Astrophys. 347, 69-76 (1999)

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6. Conclusions

High resolution échelle spectroscopy of 21 stars from the complete sample presented in Saffer et al. (1997) has revealed 9 objects that appear to belong to the young Population I . Unfortunately the age of these high-mass objects implies generally large values of the stellar rotational velocity, and in all but a few cases, quantitative metal abundances are difficult to measure (in contrast with the evolved stellar sample presented in Paper I). The available kinematic information indicates that all stars, with one possible exception (viz. PG 2219+094), originated in the Galactic disk and were subsequently ejected. However, the inclusion of proper motion data for PG 2219+094 makes a significant contribution to the estimated velocity of this object perpendicular to the Galactic plane; and the evidence points to a Population I disk origin for this target also. The completion of the high-resolution spectroscopic follow-up for the Saffer et al. (1997) sample, along with reliable proper motion determinations, will help to answer the outstanding questions concerning the nature and origin of the anomalous young, distant blue stars in the Galactic halo.

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© European Southern Observatory (ESO) 1999

Online publication: June 18, 1999