SIMBAD references

We present H, K_s, and L' filter polarimetric differential imaging (PDI) data for the transitional disk around HD100546 obtained in 2013, together with an improved re-reduction of previously published 2006 data. We reveal the disk in polarized scattered light in all three filters, achieving an inner working angle of ∼0.''1. Additional, short-exposure observations in the H and K_s filters probe the surroundings of the star down to ∼0.''03 (∼3 AU). HD100546 is fascinating because of its variety of sub-structures possibly related to forming planets in the disk, and PDI is currently the best technique for imaging them in the near-IR. For the first time ever, we detect a disk in L-band PDI data, and we constrain the outer radius of the inner hole to 14±2 AU and its eccentricity to <0.133. A dark lane is detected between ∼0.''2-0.''6 AU in the front side of the disk, which is likely an effect of the scattering angle and the scattering function of the grains. We find a spiral arm in the northeast that has no obvious connection to spiral arms seen before by other authors further out in the disk, but winds are in the same direction (clockwise). The two bright scattering peaks along the semi-major axis are asymmetric, with the southeastern one being significantly brighter. This could be related to the inner companion candidate that is close to the brighter side of the disk at the time of the observations. The scattering color is close to gray between the H and K_s filters ([H]-[K_s] = 0.19±0.11), but the scattering in the L' filter is significantly weaker ([H]-[L'] = -1.08±0.35, [K_s]-[L'] = -1.27±0.35). We measure the position angle of the disk to be 138°±3°, consistent with previous observations, and we derive the dust scattering function in the H and K_sfilters between ∼35° and ∼130° at two different radii (30-50 and 80-110 AU) and show that our results are consistent with a disk that is more strongly flared in the outer regions.