HD 97048’s Circumstellar Environment as Revealed by a Hubble Space Telescope ACS Coronagraphic Study of Disk Candidate Stars

摘要

We present the results of a coronagraphic scattered-light imaging survey of six young disk candidate stars using the Hubble Space Telescope Advanced Camera for Surveys. The observations made use of the 1.8'' occulting spot through the F606W (broad V) filter. Circumstellar material was imaged around HD 97048, a Herbig Ae/Be star located in the Chamaeleon I dark cloud at a distance of 180 pc. The material is seen between ~2'' (360 AU) and ~4'' (720 AU) from the star in all directions. A V-band azimuthally averaged radial surface brightness profile peaks at r = 2'' with a value of 19.6 ± 0.2 mag arcsec-2 and smoothly decreases with projected distance from the star as I ∝ r-3.3±0.5. An integrated flux of 16.8 ± 0.1 mag is measured between 2'' and 4'', corresponding to a scattered-light fractional luminosity lower limit of Lsca/L* > 8.4 × 10-4. Filamentary structure resembling spiral arms similar to that seen in Herbig Ae/Be disks is observed. Such structure has been attributed to the influence of orbiting planets or stellar encounters. Average surface brightness upper limits are determined for the five nondetections: HD 34282, HD 139450, HD 158643, HD 159492, and HD 195627. Possible reasons for the nondetections are disks that are too faint or disks hidden by the occulter.