NICMOS coronagraphic observations of 55 Cancri

We present new near-infrared (1.1 mum) observations of the circumstellar en vironment of the planet-bearing star 55 Cancri. With these Hubble Space Tel escope (HST) images we are unable to confirm the observation of bright scat tered radiation at longer NIR wavelengths previously reported by Trilling a nd coworkers. NICMOS coronagraphic images with detection sensitivities to s imilar to 100 mu Jy arcsec(-2) at 1.1 mum in the region 28-60 AU from the s tar fail to reveal any significant excess flux in point-spread function (PS F) subtracted images taken in two HST orbits. These new observations place flux densities in the 19-28 AU zone at a factor of 10 or more below the rep orted ground-based observations. Applying a suite of a dozen well-matched c oronagraphic reference PSFs, including one obtained in the same orbits as t he observations of 55 Cnc, yielded consistently null results in detecting a disk. We also searched for and failed to find a suggested flux-excess anis otropy in the ratio of similar to1.7:1 in the circumstellar background alon g and orthogonal to the plane of the putative disk. We suggest that, if suc h a disk does exist, then the total 1.1 km spectral flux density in an annu lar zone 28-42 AU from the star must be no more than similar to0.4 mJy, at least 10 times smaller than suggested by Trilling and Brown, upon which the ir very large estimate for the total dust mass (0.4 M+) was based. Based on the far-infrared and submillimeter flux of this system and observations of scattered light and thermal emission from other debris disks, we also expe ct the intensity of the scattered light to be at least an order of magnitud e below our upper limits.