Discovery of PSR J0108-1431, the closest known neutron star
T. M. Tauris (Institute of Physics and Astronomy, Aarhus University, Denmark),
L. Nicastro (IRA - CNR, Bologna, Italy),
S. Johnston (RCfTA, University of Sydney, Australia),
M. Bailes (ATNF, CSIRO, Australia),
R. N. Manchester (ATNF, CSIRO, Australia),
A. G. Lyne (NRAL, Jodrell Bank, University of Manchester, UK),
N. D'Amico (University of Palermo and IRA - CNR, Bologna, Italy),
J. Glowacki (Parkes Observatory, ATNF, CSIRO, Australia),
J. F. Bell (MSSSO, Australian National University, Australia),
D. R. Lorimer (NRAL, Jodrell Bank, University of Manchester, UK),
P. A. Harrison (NRAL, Jodrell Bank, University of Manchester, UK)
Abstract There are about 600 known radio pulsars in our Galaxy, typically at distances of a few kpc, as indicated by the amount of dispersion of the pulses in the ionized component of the interstellar medium. Here we report the discovery of PSR J0108-1431, a pulsar which has the lowest known dispersion measure, 1.83 pc cm^-3. Reasonable models of the interstellar electron density distribution indicate that its distance is less than 100 pc, making it the closest known radio pulsar and probably the closest known neutron star. Furthermore this pulsar has the lowest radio luminosity of any known pulsar by more than an order of magnitude. Such a weak pulsar in the solar neighbourhood implies a large population of active but low-luminosity pulsars in the galactic halo. X-ray observations of PSR J0108-1431 may determine whether or not there is significant decay of the surface magnetic field in isolated neutron stars and distinguish between different cooling and heating models.