Untitled - Laboratoire d'Astrophysique de l'Observatoire de Grenoble

2.2 µ m
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11.7 µ m
Figure 6.1: Left Panel: K-band image of the edge-on disk HK Tauri B ontained with NACO/VLT. (image
from Ménard et al. (2005), in prep.). Right panel: 12µm scattered light image of HK Tau B obtained with
KECK/LWS. Image from McCabe et al. (2003)
light at 4µm comes from a layer located twice as close to the ring midplane than the visible scattered light
(see Figure 6.2). Combined with the need for larger grains to account for the scattering phase function in the
thermal infrared, and the need for very small grains at the disk surface to account for the large polarisation
observed (Silber et al. 2000, ApJ, 536, L89), this is the first direct evidence for the stratification of dust grains,
possibly as a result of vertical settling. This settling is a necessary step for dust to accumulate in the disk
midplane and to grow into planetesimals, i.e., to start forming larger bodies, eventually rocky cores of planets,
in the disks.
0.8 µ m 3.8 µ m
1"
Figure 6.2: Left Panel: HST/ACS F814W image of the circumbinary ring of GG Tau (image from Krist et al.
2005, ApJ, in press). Right panel: 3.8uµm scattered light image obtained with KECK. Image from Duchêne
et al. (2004)
To further probe small grains, and whenever possible, polarimetric mapping is also obtained. However, due
to the paucity of polarimetric data, studies have been completed only for a few sources so far. Silber et al.
(2000, ApJ, 536, L89) presented to first polarisation of a disk (GG Tau). Glauser et al. (2005) in prep. are
finalising the analysis for IRAS 04158+2805. Our group is one of the very few using that powerful property of
light for disk studies.
In a parallel approach to scattered light images, we pursue millimeter interferometric images of T Tauri
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