Discovery of near-ultraviolet counterparts to millisecond pulsars in the
  globular cluster 47 Tucanae
  We report the discovery of the likely white dwarf companions to radio
millisecond pulsars 47 Tuc Q and 47 Tuc S in the globular cluster 47 Tucanae.
These blue stars were found in near-ultraviolet images from the Hubble Space
Telescope for which we derived accurate absolute astrometry, and are located at
positions consistent with the radio coordinates to within 0.016 arcsec
(0.2sigma). We present near-ultraviolet and optical colours for the previously
identified companion to millisecond pulsar 47 Tuc U, and we unambiguously
confirm the tentative prior identifications of the optical counterparts to 47
Tuc T and 47 Tuc Y. For the latter, we present its radio-timing solution for
the first time. We find that all five near-ultraviolet counterparts have
U300-B390 colours that are consistent with He white dwarf cooling models for
masses ~0.16-0.3 Msun and cooling ages within ~0.1-6 Gyr. The Ha-R625 colours
of 47 Tuc U and 47 Tuc T indicate the presence of a strong Ha absorption line,
as expected for white dwarfs with an H envelope.
