Expansion velocities and core masses of bright planetary nebulae in the Virgo Cluster

The line-of-sight velocities and [ O III] 5007 angstrom expansion velocities are measured for 11 planetary nebulae (PNs) in the Virgo Cluster core, at 15 Mpc distance, with the FLAMES spectrograph on the ESO VLT. These PNs are located about halfway between the two giant elliptical galaxies M87 and M86. From the [ O III] 5007 angstrom line profile widths, the average half-width at half-maximum expansion velocity for this sample of 11 PNs is (v) over bar (HWHM) = 16.5 km s(-1)(rms = 2.6 km s(-1)). We use the PN subsample bound to M87 to remove the distance uncertainties and the resulting [ O III] 5007 angstrom luminosities to derive the central star masses. We find these masses to be at least 0.6 M-circle dot and obtain PN observable lifetimes t(PN) < 2000 yr, which imply that the bright PNs detected in the Virgo Cluster core are compact, high-density nebulae. We finally discuss several scenarios for explaining the high central star masses in these bright M87 halo PNs.