NICMOS Coronagraphic Observations of 55 Cancri

We present new near-infrared (1.1-micron) observations of the circumstellarenvironment of the planet-bearing star 55 Cancri. With these Hubble SpaceTelescope images we are unable to confirm the observation of bright scatteredradiation at longer NIR wavelengths previously reported by Trilling & Brown(1998), and Trilling, Brown & Rivkin (2000). NICMOS coronagraphic images withdetection sensitivities to ~ 100 microJy arcsec$^{-2}$ at 1.1 microns in theregion 28 - 60 AU from the star fail to reveal any significant excess flux inpoint- spread-function (PSF) subtracted images taken in two Hubble SpaceTelescope orbits. These new observations place flux densities in the 19-28 AUzone at a factor of ten or more below the reported ground-based observations.Applying a suite of a dozen well-matched coronagraphic reference PSFs,including one obtained in the same orbits as the observations of 55 Cnc,yielded consistently null results in detecting a disk. We also searched for,and failed to find, a suggested flux-excess anisotropy in the ratio of ~1.7:1in the circumstellar background along and orthogonal to the plane of theputative disk. We suggest that, if such a disk does exist, then the total1.1-micron spectral flux density in an annular zone 28 - 42 AU from the starmust be no more than ~0.4mJy, at least ten times smaller than suggested byTrilling and Brown, upon which their very large estimate for the total dustmass (0.4~$M_{\earth}$) was based. Based on the far infrared and submillimeterflux of this system and observations of scattered light and thermal emissionfrom other debris disks, we also expect the intensity of the scattered light tobe at least an order of magnitude below our upper limits.