Letter to the Editor

Optical identification of the companion to PSR J1911-5958A, the pulsar binary in the outskirts of NGC 6752

¹ Astronomical Institute, Utrecht University, PO Box 80 000, 3508 TA Utrecht, The Netherlands
² Dept. of Astronomy and Astrophysics, Univ. of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada
³ Dept. of Astronomy, Univ. of Washington, Box 351580, Seattle, WA 98195-1580, USA

Corresponding author: C. G. Bassa, c.g.bassa@astro.uu.nl

Received: 17 July 2003
Accepted: 1 September 2003

Abstract

We report on the identification of the optical counterpart of the binary millisecond pulsar PSR J1911-5958A, located in the outskirts of the globular cluster NGC 6752. At the position of the pulsar we find an object with , , . The object is blue with respect to the cluster main sequence by 0.8 mag in . We argue that the object is the white dwarf companion of the pulsar. Comparison with white dwarf cooling models shows that this magnitude and colors are consistent with a low-mass white dwarf at the distance of NGC 6752. If associated with NGC 6752, the white dwarf is relatively young, Gyr, which sets constraints on the formation of the binary and its ejection from the core of the globular cluster.