2003ApJ...596L.211F

We have used deep high-resolution multiband images taken at the ESO Very Large Telescope to identify the optical binary companion to the millisecond pulsar (PSR J1911-5958A) located in the halo of the Galactic globular cluster NGC 6752. The object turns out to be a blue star whose position in the color-magnitude diagram is consistent with the cooling sequence of a low-mass (M∼0.17-0.20 M_☉), low-metallicity helium white dwarf (He WD) at the cluster distance. This is the second He WD, with this mass, that has been found to orbit a millisecond pulsar in Galactic globular clusters. The anomalous position of PSR J1911-5958A with respect to the globular cluster center (∼6') suggested that this system has recently (≲1 Gyr) been ejected from the cluster core as the result of a strong dynamical interaction. The data presented here allow us to constrain the cooling age of the companion within a fairly narrow range (∼1.2-2.8 Gyr), therefore suggesting that such a dynamical encounter must have acted on an already recycled millisecond pulsar.