arXiv:astro-ph/0210325v1 15 Oct 2002 h xetdU msin(i.1) lhuhtepeitdm majo predicted the the ones, measured Although the 1b). than fainter (Fig. systematically emission are UV expected the rdce magnitudes predicted iue1. Figure rather is data c parallax their the hence of ear large, basis to very the are B on errors from subluminous parallax types the spans stars classification these spectral sig their A T entries. while the M 46 of have for Part cros value objects Main we parallax of the significant stars, in a such objects finding for with log, search positions To sources B=16.5. the UV to dominate the Hot down and 1600 Atlantis. stars objects, Ophiu shuttle blue at blue toward among of space obtained numerous image the are was UV of stars image nous a board The in on instrument detected 2002). FAUST sources al. UV et 228 (Formiggini the of parts OPHIUCHUS TOWARD SOURCES UV FAUST THE AMONG STARS SD/WD HIDDEN Number ytei htmtyo pcrldt a efre norde in performed was data spectral of photometry Synthetic owiedafo o udafsasaefuda pia coun optical as found are stars hot or dwarf white No 10 0 5 . . 0015.0 10.0 5.0 0.0 )Hsormo h acltdM calculated the of Hystogram a) colo hsc n srnm n h ieObservatory Wise The Israel and University, Astronomy Tel-Aviv and Physics of School FORMIGGINI LILIANA M V V ausa xetdfrW rsbwr tr Fg 1a), (Fig. stars subdwarf or WD for expected as values

mag predicted 10 15 20 0 5 . . 001. 20.0 15.0 10.0 5.0 0.0 V antds )FUTversus FAUST b) magnitudes; FAUST mag icn number nificant iyo h stars the of rity asfiainas lassification unreliable. yF o all For F. ly ,wt the with A, ˚ opredict to r s-identified population cocata- ycho agnitudes sublumi- chus ter- 2 populate a region inside the dotted lines. The open squares show the stars for which FAUST measured a brighter UV than the one pre- dicted on the basis of the photometric color. These uv-excess (also marked by asterisk in Fig. 1a) should belong to the subdwarf or lumi- nosity classes but one, already classified as an Am . Nine of the twelve uv-excess stars with MV ≥ 5 were observed at the 1.0 meter telescope at the Wise Observatory. For all, but one, the Balmer lines are moderately broadened. The dashed line in Fig 2 is the model profile from Wesemael et al. (1980). Two of the observed candidates can be fitted with atmospheres of log g ≥ 7, as for white dwarfs stars, and six are sdB stars.

N.65 log g=6, T=30000 N.123 log g=6, T=30000 N.148 log g=6, T=30000

N.194 log g=6, T=30000 N.206 log g=6, T=30000 N.211 log g=6, T=30000

N.214 log g=7, T=30000 N.228 log g=8, T=30000 N.220

−100 −50 0 50 100 −100 −50 0 50 100 −100 −50 0 50 100 ∆λ(Α)

Figure 2. Hβ line profile observed (line) compared with model atmospheres profile (dashed).

It is known that the PG survey is quite incomplete at bright magni- tudes. This analysis shows that combining the UV information with even poorly determined parallaxes, some new sd/wd stars are detected and that indeed more such bright stars are still unrecognized in the existing samples. Extending this analysis to the other FAUST fields previously identified at the Wise Observatory, more bright sd/wd stars, suitable for a determina- tion of the space density at the bright end of the function can be identified.

References Formiggini, L., Brosch, N., Almoznino, E., Bowyer, S. and Lampton, M., 2002, MNRAS, 332, 441. Wesemael F., Auer L.H., Van Horn H.M. and Savedoff M.P. 1980, ApJS, 43,159.