Dissecting the Moth: Resolving the offset debris ring around HD61005 with VLT/NACO


E. Buenzli C. Thalmann A. Boccaletti A. Vigan J.C. Augereau G. Chauvin F. Menard J. Carson G. Montagnier M.R. Meyer A.M. Lagrange D. Mouillet S. Desidera S. Messina E. Covino J. Alcala A. Lanzafame E. Brugaletta M. Bonavita M. Bonnefoy A. Eggenberger R. Gratton T. Henning C. Moutou L.B.F.M. Waters J.L. Beuzit


ETH Zurich MPIA LESIA LAM LAOG LAOG LAOG MPIA ESO ETH Zurich LAOG LAOG INAF Padova INAF Catania INAF Napoli INAF Napoli INAF Catania INAF Catania University of Toronto LAOG LAOG INAF Padova MPIA LAM University of Amsterdam LAOG


HD61005 is a 90 Myr old G8V star at 34.5 pc that hosts a debris disk which has been previously resolved by HST at 1.1 and 0.6 microns. The disk shows significant interaction with the ISM and has been dubbed "the Moth" because of the strong asymmetry about its major axis (Hines et al. 2007). From polarimetric observations it was inferred that the circumstellar material consists of two distinct components, a near-edge on disk or ring, and a swept-back feature resulting from the ISM interaction (Maness et al. 2009).

We resolve both components with VLT/NACO H-band imaging. Our observations are part of a VLT/NACO large program to complete the sample of young nearby stars surveyed for the presence of gas giant planets with large orbital radii (PI: J.L. Beuzit). Using optimized Angular Differential Imaging techniques (smart-ADI, LOCI) as well as classical PSF subtraction to subtract the light of the star, we find the disk component resolved to a ring of inclination i 85° and radius r 60 AU, with a sharp inner edge and the ring center offset from the star by several AU. Together these two features could indicate a planetary companion sculpting the ring. From our imaging data we also derive limits for the mass of such a companion.

The ring shows a brightness asymmetry along both the major and minor axis. The brighter front side indicates forward scattering grains, while the brightness difference between the NE- and SW-components results at least partly from the ring center offset. We discuss the constraints on geometry and grain properties for the ring inferred from our observations. The swept component is shown to be two streamers originating near the NE- and SW-edges of the debris ring.

Attached documents

Lyot2010proc s5 talk BuenzliE.pdf
PDF, 714 kb