X-raying the AU Microscopii debris disk

TL;DR

This study uses high-resolution X-ray spectroscopy to investigate the composition and structure of AU Mic's debris disk, suggesting it has a low-density inner hole with minimal small grains or gas.

Contribution

First application of X-ray transmission spectroscopy to characterize the chemical composition and structure of a debris disk around a young star.

Findings

X-ray upper limits are consistent with low-density inner holes.

Results align with UV absorption measurements.

Debris disk likely has minimal sub-micron grains or gas in the inner region.

Abstract

AU Mic is a young, nearby X-ray active M-dwarf with an edge-on debris disk. Debris disk are the successors of the gaseous disks usually surrounding pre-main sequence stars which form after the first few Myrs of their host stars' lifetime, when - presumably - also the planet formation takes place. Since X-ray transmission spectroscopy is sensitive to the chemical composition of the absorber, features in the stellar spectrum of AU Mic caused by its debris disk can in principle be detected. The upper limits we derive from our high resolution Chandra LETGS X-ray spectroscopy are on the same order as those from UV absorption measurements, consistent with the idea that AU Mic's debris disk possesses an inner hole with only a very low density of sub-micron sized grains or gas.