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We present images from five observations of the quasar 3C 273 with the Chandra X-Ray Observatory. The jet has at least four distinct features that are not resolved in previous observations. The first knot in the jet (A1) is very bright in X-rays. Its X-ray spectrum is well fitted with a power law with (where a p 0.60 ‫ע‬ 0.05 ). Combining this measurement with lower frequency data shows that a pure synchrotron model can fit Ϫa S ∝ n n the spectrum of this knot from 1.647 GHz to 5 keV (over nine decades in energy) with , similar a p 0.76 ‫ע‬ 0.02 to the X-ray spectral slope. Thus, we place a lower limit on the total power radiated by this knot of 1.5 # ergs s Ϫ1 ; substantially more power may be emitted in the hard X-ray and g-ray bands. Knot A2 is also 43 10 detected and is somewhat blended with knot B1. Synchrotron emission may also explain the X-ray emission, but a spectral bend is required near the optical band. For knots A1 and B1, the X-ray flux dominates the emitted energy. For the remaining optical knots (C through H), localized X-ray enhancements that might correspond to the optical features are not clearly resolved. The position angle of the jet ridge line follows the optical shape with distinct, aperiodic excursions of ‫1ע‬Њ from a median value of Ϫ138Њ .0. Finally, we find X-ray emission from the "inner jet" between 5Љ and 10Љ from the core.

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We report the detection of well-resolved, extended X-ray emission from the young planetary nebula BD ϩ30Њ3639 using the Advanced CCD Imaging Spectrometer (ACIS) aboard the Chandra X-ray Observatory. The X-ray emission from BD ϩ30Њ3639 appears to lie within, but is concentrated to one side of, the interior of the shell of ionized gas seen in high-resolution optical and IR images. The relatively low X-ray temperature ( K) and asymmetric 6T ∼ 3 # 10 X morphology of the X-ray emission suggest that conduction fronts are present and/or mixing of shock-heated and photoionized gas has occurred, and furthermore hints at the presence of magnetic fields. The ACIS spectrum suggests that the X-ray-emitting region is enriched in the products of nuclear burning. Our detection of extended X-ray emission from BD ϩ30Њ3639 demonstrates the power and utility of Chandra imaging as applied to the study of planetary nebulae.

We investigate the spatial distribution of X-ray emitting plasma in a sample of young Orion Nebula Cluster stars by modulation of their X-ray light-curves due to stellar rotation. The study, part of the Chandra Orion Ultradeep Project (COUP), is made possible by the exceptional length of the observation: 10 days of ACIS integration during a time span of 13 days, yielding a total of 1616 detected sources in the 17 × 17 arcmin field of view. We here focus on a subsample of 233 X-ray-bright stars with known rotational periods. We search for X-ray modulation using the Lomb Normalized Periodogram method.X-ray modulation related to the rotation period is detected in at least 23 stars with periods between 2 and 12 days and relative amplitudes ranging from 20% to 70%. In 16 cases, the X-ray modulation period is similar to the stellar rotation period while in seven cases it is about half that value, possibly due to the presence of X-ray emitting structures at opposite stellar longitudes. These results constitute the largest sample of low mass stars in which X-ray rotational modulation has been observed. The detection of rotational modulation indicates that the X-ray emitting regions are distributed inhomogeneneously in longitude and do not extend to distances significantly larger than the stellar radius. Modulation is observed in stars with saturated activity levels (L X /L bol ∼ 10 −3 ) showing that saturation is not due to the filling of the stellar surface with X-ray emitting regions.