The Inner Disk Structure, Disk-Planet Interactions, and Temporal Evolution in the Beta Pictoris System: A Two-Epoch HST/STIS Coronagraphic Study

TL;DR

This study uses two-epoch HST/STIS coronagraphic images to analyze the detailed structure, asymmetries, and evolution of the Beta Pictoris debris disk, revealing insights into disk-planet interactions and temporal changes.

Contribution

It provides the most sensitive optical images of the Beta Pictoris disk at two epochs, characterizing its structure, asymmetries, and brightness evolution, and discusses implications for planet-disk interactions.

Findings

Disk is warped and exhibits asymmetries.

No significant brightness change detected over 15 years.

Disk features are consistent with planetesimal and giant planet interactions.

Abstract

We present deep HST/STIS coronagraphic images of the Beta Pic debris disk obtained at two epochs separated by 15 years. The new images and the re-reduction of the 1997 data provide the most sensitive and detailed views of the disk at optical wavelengths as well as the yet smallest inner working angle optical coronagraphic image of the disk. Our observations characterize the large-scale and inner-disk asymmetries and we identify multiple breaks in the disk radial surface brightness profile. We study in detail the radial and vertical disk structure and show that the disk is warped. We explore the disk at the location of the Beta Pic b super-jupiter and find that the disk surface brightness slope is continuous between 0.5 and 2.0 arcsec, arguing for no change at the separations where Beta Pic b orbits. The two epoch images constrain the disk surface brightness evolution on orbital and radiation pressure blow-out timescales. We place an upper limit of 3% on the disk surface brightness change between 3-5 arcsec, including the locations of the disk warp, and the CO and dust clumps. We discuss the new observations in the context of high-resolution multi-wavelength images and divide the disk asymmetries in two groups: axisymmetric and non-axisymmetric. The axisymmetric structures (warp, large-scale butterfly, etc.) are consistent with disk structure models that include interactions of a planetesimal belt and a non-coplanar giant planet. The non-axisymmetric features, however, require a different explanation.