(excluding H$_\epsilon$ to avoid the  H line), the lines $\lambda\lambda$ 4026 Å, 4388 Å, 4471 Å, 4921 Å and the lines $\lambda\lambda$ 4542 Å, 4686 Å for the helium-poor stars. For the helium-rich stars we also included the lines $\lambda\lambda$ 4713 Å, 5015 Å and 5044 Åin the fit. The results are given in Table \[tab-par\] for NGC 2808 and Table \[tab-paro\] for $\omega$ Cen.

[psfile=0505\_4.ps hscale=95 vscale=95 hoffset=-70 voffset=-350 angle=0]{}

As can be seen from Table \[tab-par\] W21882 shows both a much higher effective temperature (67,000 K) and surface gravity ([$\log {\rm g}$]{} = 6.99) than all other stars. These stellar parameters indicate that W21882 may be a low-mass white dwarf, just in the mass range between the most massive He white dwarfs and the least massive C/O white dwarfs (cf. Fig \[W21882\]). This suggests an absolute magnitude of $M_V \approx$, which would place W21882 at a distance of at most 4 kpc (zero reddening assumed), compared to 9.6 kpc for NGC 2808. Unfortunately, the radial velocity estimates derived from our spectra are too crude to determine cluster membership. However, as can be seen from Table \[tab-par\], the model fit to W21882 has by far the largest $\chi^2$ value 