# Discovery of extreme asymmetry in the debris disk surrounding HD 15115

## TL;DR

This paper reports the first optical and near-infrared scattered light detection of the HD 15115 debris disk, revealing extreme asymmetry likely caused by dynamical perturbations from a nearby star, supporting its membership in the Beta Pic group.

## Contribution

First detection of the HD 15115 debris disk in scattered light, revealing extreme asymmetry and suggesting dynamical influence from a nearby star.

## Key findings

- East side of disk extends to ~315 AU
- West side of disk extends beyond 550 AU
- Disk has blue scattering color similar to AU Mic

## Abstract

We report the first scattered light detection of a dusty debris disk surrounding the F2V star HD 15115 using the Hubble Space Telescope in the optical, and Keck adaptive optics in the near-infrared. The most remarkable property of the HD 15115 disk relative to other debris disks is its extreme length asymmetry. The east side of the disk is detected to ~315 AU radius, whereas the west side of the disk has radius >550 AU. We find a blue optical to near-infrared scattered light color relative to the star that indicates grain scattering properties similar to the AU Mic debris disk. The existence of a large debris disk surrounding HD 15115 adds further evidence for membership in the Beta Pic moving group, which was previously argued based on kinematics alone. Here we hypothesize that the extreme disk asymmetry is due to dynamical perturbations from HIP 12545, an M star 0.5 degrees (0.38 pc) east of HD 15115 that shares a common proper motion vector, heliocentric distance, galactic space velocity, and age.