AAS 195th Meeting, January 2000
Session 112. Chandra
Display, Saturday, January 15, 2000, 9:20am-4:00pm, Grand Hall

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[112.04] Discovery of Spatial Structures in the X-ray Image of the Crab Nebula

M. C. Weisskopf (NASA/MSFC), H. L. Marshall (MIT/CSR), J. J. Hester (Arizona S. U.), A. F. Tennant (NASA/MSFC), G. E. Allen (MIT/CSR), Y. Butt (SAO/CfA), R. F. Elsner (NASA/MSFC), M. S. Elvis, D. E. Graessle, E. M. Kellogg (SAO/CfA), J. J. Kolodiejczak (NASA/MSFC), J. S. Nichols (SAO/CfA), S. L. O'Dell (NASA/MSFC), M. J. Pivovaroff (MIT/CSR), P. P. Plucinsky (SAO/CfA), N. S. Schulz (MIT/CSR), D. A. Swartz (NASA/MSFC), S. D. Vrtilek (SAO/CfA)

During the orbital activation and calibration of the Chandra X-ray Observatory,we observed the Crab Nebula and Pulsar, using the High-Energy Transmission Grating (HETG), read-out with the ACIS-S array of 6 CCDs. The 2800-s observation obtained a high-resolution spectrum of the pulsar, as part of the HETG on-orbit calibration program. A fascinating by-product of this observation is the high-angular-resolution zeroth-order image. The pulsar is so bright that it saturates the central position and thus appears as a hole in the image. On the other hand, the nebula is spatially resolved at better than one arcsec. This observation not only confirmed the existence of spatial structures hinted at by previous observations --- such as the jet and counter jet (e.g., Hester et al. 1995, Ap.J. 448,240) --- but also revealed new, previously unobservable x-ray features. These features include the inner portions of the previously reported jet-like structure, an elliptical ring of x-ray emission centered on the pulsar with semi-major axis perpendicular to the jets, and at least two bright knots in the ellipse, one at its projected intersection with the jet. Determining the spectral dependence of these features is somewhat challenging, due to pulse pileup in the brighter portions of the nebula. Here we present detailed results of the analysis.


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