HD 97048's Circumstellar Environment as Revealed by aHubble Space TelescopeACS Coronagraphic Study of Disk Candidate Stars

We present the results of a coronagraphic scattered-light imaging survey ofsix young disk candidate stars using the Hubble Space Telescope Advanced Camerafor Surveys. The observations made use of the 1.8" occulting spot through theF606W (broad V) filter. Circumstellar material was imaged around HD 97048, aHerbig Ae/Be star located in the Chamaeleon I dark cloud at a distance of 180pc. The material is seen between ~2" (360 AU) and ~4" (720 AU) from the star inall directions. A V-band azimuthally-averaged radial surface brightness profilepeaks at r = 2" with a value of 19.6 +/- 0.2 mag arcsec^-2 and smoothlydecreases with projected distance from the star as r^(-3.3 +/- 0.5). Anintegrated flux of 16.8 +/- 0.1 mag is measured between 2" and 4",corresponding to a scattered-light fractional luminosity lower limit of 8.4 x10^-4. Filamentary structure resembling spiral arms similar to that seen inHerbig Ae/Be disks is observed. Such structure has been attributed to theinfluence of orbiting planets or stellar encounters. Average surface brightnessupper limits are determined for the five non-detections: HD 34282, HD 139450,HD 158643, HD 159492, and HD 195627. Possible reasons for the non-detectionsare disks that are too faint or disks hidden by the occulter.Comment: Accepted for publication in the Astronomical Journal. 27 pages, 6 figure