EDP Sciences
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Volume 488, Number 3, September IV 2008
Page(s) 1027 - 1030
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:200810212
Published online 30 July 2008

A&A 488, 1027-1030 (2008)
DOI: 10.1051/0004-6361:200810212

A possible optical counterpart to the old nearby pulsar J0108-1431

R. P. Mignani1, G. G. Pavlov2, and O. Kargaltsev2, 3

1  Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
    e-mail: rm2@mssl.ucl.ac.uk
2  Department of Astronomy and Astrophysics, Pennsylvania State University, PA 16802, USA
    e-mail: pavlov@astro.psu.edu
3  Department of Astronomy, University of Florida, 32611, USA
    e-mail: oyk100@astro.ufl.edu

Received 16 May 2008 / Accepted 1 July 2008

Context. The multi-wavelength study of old (>100 Myr) radio pulsars holds the key to understanding the long-term evolution of neutron stars, including the advanced stages of neutron star cooling and the evolution of the magnetosphere. Optical/UV observations are particularly useful for such studies because they allow one to explore both thermal and non-thermal emission processes. In particular, studying the optical/UV emission constrains the temperature of the bulk of the neutron star surface, too cold to be measured in X-ray observations.
Aims. Aim of this work is to identify the optical counterpart of the very old (166 Myr) radio pulsar J0108-1431.
Methods. We have re-analyzed our original Very Large Telescope  (VLT) observations, where a very faint object was tentatively detected close to the radio position, near the edge of a field galaxy.
Results. We found that the backward extrapolation of the PSR J0108-1431 proper motion recently measured by Chandra  fits the position of this object. Based on that, we propose it as a viable candidate for the optical counterpart to PSR J0108-1431. The object fluxes ( $U =26.4 \pm0.3$; $B \approx
27.9$; $V \ge 27.8$) are consistent with a thermal spectrum with a brightness temperature of $\sim $ $9\times 10^4$ K (for R = 13 km at a distance of 130 pc), emitted from the bulk of the neutron star surface.
Conclusions. New optical observations are required to confirm the optical identification of PSR J0108-1431 and measure its spectrum.

Key words: astrometry -- stars: pulsars: individual: PSR J0108-1431

© ESO 2008