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Pulsar wind nebulae (PWNe) studies with the Chandra X-ray Observatory haveopened a new window to address the physics of pulsar winds, zoom on theirinteraction with their hosting supernova remnant (SNR) and interstellar medium,and identify their powering engines. We here present a new 70 ks, plus anarchived 18 ks, Chandra ACIS observation of the SNR CTB 87 (G74.9+1.2),classified as a PWN with unusual radio properties and poorly studied in X-rays.We find that the peak of the X-ray emission is clearly offset from the peak ofthe radio emission by ~100" and located at the southeastern edge of the radionebula. We detect a point source - the putative pulsar - at the peak of theX-ray emission and study its spectrum separately from the PWN. This new pointsource, CXOU J201609.2+371110, is surrounded by a compact nebula displaying atorus-like structure and possibly a jet. A more extended diffuse nebula isoffset from the radio nebula, extending from the point source to the northwestfor ~250" The spectra of the point source, compact nebula and extended diffusenebula are all well described by a power law model with a photon index of 1.1(0.7-1.6), 1.2 (0.9-1.4) and 1.7 (1.5-1.8), respectively, for a column densityN_H = 1.38 (1.21-1.57) x 10^22 cm^-2 (90% confidence). The total X-rayluminosity of the source is ~1.6 x 10^34 erg s^-1 at an assumed distance of 6.1kpc, with ~2% and 6% contribution from the point source and compact nebula,respectively. The observed properties suggest that CTB 87 is an evolved (~5-28kyr) PWN, with the extended radio emission likely a `relic' PWN, as in Vela-Xand G327.1-1.1. To date, however, there is no evidence for thermal X-rayemission from this SNR, and the SNR shell is still missing, suggestingexpansion into a low-density medium (n_0 < 0.2 cm^-3, assuming D = 6.1 kpc),likely caused by a stellar wind bubble blown by the progenitor star.

X-ray Observations of the Supernova Remnant CTB 87 (G74.9+1.2): An Evolved Pulsar Wind Nebula