DETECTION OF X-RAY EMISSION FROM THE VERY OLD PULSAR J0108-1431

PSR J0108-1431 is a nearby, 170 Myr old, very faint radio pulsar near the pulsar death line in the P-(P)over dot diagram. We observed the pulsar field with the Chandra X-ray Observatory and detected a point source (53 counts in a 30 ks exposure; energy flux (9 +/- 2) x 10(-15) erg cm(-2) s(-1) in the 0.3-8 keV band) close to the radio pulsar position. Based on the large X-ray/optical flux ratio at the X-ray source position, we conclude that the source is the X-ray counterpart of PSR J0108-1431. The pulsar spectrum can be described by a power-law model with photon index Gamma approximate to 2.2 and luminosity L0.3-8 keV approximate to 2 x 10(28)d(130)(2) erg s(-1), or by a blackbody model with temperature kT approximate to 0.28 keV and bolometric luminosity L-bol approximate to 1.3 x 10(28)d(130)(2) erg s(-1), for a plausible hydrogen column density N-H = 7.3 x 10(19) cm(-2) (d(130) = d/130 pc). The pulsar converts similar to 0.4% of its spin-down power into X-ray luminosity, i.e., its X-ray efficiency is higher than for most younger pulsars. From the comparison of the X-ray position with the previously measured radio positions, we estimated the pulsar proper motion of 0.2 arcsec yr(-1) (V-perpendicular to approximate to 130d(130) km s(-1)), in the south-southeast direction.