STScI Preprint #1271

HST Observations of the M87 Jet

We present highlights and preliminary results of our HST observing programs on the M87 jet. We confirm previously known similarities between the radio and optical jets, but also describe a wealth of differences and new structural details. We identify numerous compact optical features, as well as new structures in the shock-like knots A and C. We also find considerable evidence for structure in the jet as a function of distance from the jet axis - evidence is seen for radial structure in the radio / optical spectrum, in the optical / optical spectrum, and in the polarimetry. Our monitoring between 1994 and 1996 shows numerous features with superluminal speeds in the range of 4c to 6c, as well as the emergence of new superluminal components and rapid fading of old features.

The Large Scale X-Ray Emission from M87

We describe asymmetrical features in a long exposure X-ray map of M87 made with the ROSAT High Resolution Imager (HRI). A bright triangular region is marked by a linear 'spur' along one edge. The structure of this spur suggests an interpretation of a tangential view of a shock front 18 kpc long. None of the brighter features are spatially coincident with radio or optical structures so we concur with earlier investigations that most of the emission arises from thermal processes.

X-Ray Variability in M87: 1992-1998

Beginning in 1995 June, we have obtained an observation of M87 with the ROSAT High Resolution Imager (HRI) every 6 months. We present the measurements of X-ray intensity for the core and knot A through 1998 January. We find significant changes in both components. for the core, intensities measured in 95 Jun, 96 Dec, and 97 Dec are roughly 30% higher than the values obtained at three intervening times. For knot A, a secular decrease of approximately 15% is interrupted only by an intensity jump (3 ) in 1997 Dec. Because the background used for subtraction is probably underestimated, we suspect the actual variation is somewhat greater than these values indicate.

Status:

To appear in: the proceedings of the M87 Workshop held September 1997 at Ringberg Castle

Affiliations:

¹) Space Telescope Science Institute, 3710 San Martin Drive, Baltimore, MD 21218, USA
²) Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138
³) University of New Mexico, 800 Yale Boulevard, Albuquerque, NM 87131