The proper motion of the isolated neutron star RX J1605.3+3249

¹ Mullard Space Science Laboratory, Holmbury St. Mary, Dorking – Surrey, RH5 6NT, UK e-mail: [sz;rm]@mssl.ucl.ac.uk
² Istituto di Astrofisica Spaziale e Fisica Cosmica, via Bassini 15, 20133 Milan, Italy e-mail: deluca@iasf-milano.inaf.it
³ Universitá di Padova, Dipartimento di Fisica, via Marzolo 8, 35131 Padova, Italy e-mail: roberto.turolla@pd.infn.it

Received: 12 April 2006
Accepted: 29 June 2006

Abstract

Aims.We present a new optical observation of the X-ray dim isolated neutron star RX J1605.3+3249, performed in 2005 with the Wide Field Channel (WFC) of the Advanced Camera for Surveys (ACS) on board Hubble Space Telescope, aimed at measuring the neutron star proper motion.

Methods.We have compared the target position with the one measured in a previous HST image of the field obtained in 2001.

Results.We infer a proper motion of  ± 3.1 mas/yr, corresponding to a star velocity  km s^-1 at 100 pc distance. Our measurement refines the result recently reported by Motch et al. (2005, A&A, 429, 257), and confirms the optical source as the counterpart of the neutron star.