| タイトル | HST/ACS Coronagraphic Observations of the HD 163296 Circumstellar Disk: Evidence of Time-Variable Self-Shadowing? |
| 著者（英） | Golimowski, D.; Clampin, Mark; Illingworth, G.; Krist, J.; Wisniewski, J.; Grady, C.; Ardila, D.; Dowling, Lorraine |
| 著者所属（英） | NASA Goddard Space Flight Center |
| 発行日 | 2007-06-08 |
| 言語 | eng |
| 内容記述 | We present Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) coronagraphic observations of the Herbig Ae star HD 163296. HD 163296's scattered light disk was resolved in the F606W and F814W filters in observations obtained In 2003 and in the F435W filter in observations obtained in 2004. Analysis of single-epoch data indicates that the disk (V-I) color is redder than the observed stellar (V-I) color. This spatially uniform red disk color might be indicative of either an evolution in the grain size distribution (i.e. grain growth) and/or composition. Both of these processes would be consistent with the observed flat geometry of the outer disk, as diagnosed by the observed r$(exp -3)$ power law behavior of its median azimuthally averaged disk surface brightness, which suggest that grain evolution is occurring. Comparison of ACS and STIS epoch scattered light data reveals differences in the observed disk surface brightnesses, of order 1 mag arcsec$(exp -2)$, in both V and white-light filter bandpasses. Along with the observed variability in the visibility and surface brightness of the ansa(e) in the disk, and spectropolarimetric variability of the system, these results suggest that the resolved scattered light disk is variable, a phenomenon not previously observed in any other Herbig protoplanetary system We speculate that the observed behavior might be attributable to the variable inflation of the scale height of the inner disk wall, which results in variable self-shadowing of the outer disk. |
| NASA分類 | Astronomy |
| 権利 | Copyright |
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