THE VELA PULSAR AND ITS LIKELY COUNTER-JET IN THE Ks BAND

We report the first high spatial resolution near-infrared (near-IR) imaging of the Vela pulsar in the Ks band obtained with the new adaptive optics system recently mounted on the Gemini-South telescope. For the first time, we have firmly detected the pulsar in this band with Ks 21.8 mag, and have resolved in detail an extended feature barely detected previously in the immediate vicinity of the pulsar in the JsH bands. The pulsar Ks flux is fully consistent with the extension of the flat optical spectrum of the pulsar toward the IR and does not confirm the strong IR flux excess in the pulsar emission suggested earlier by the low spatial resolution data. The extended feature is about two times brighter than the pulsar and is likely associated with its X-ray counter-jet. It extends ~2'' southward of the pulsar along the X-ray counter-jet and shows knot-like structures and a red spectrum.