Signpost of Multiple Planets in Debris Disks

TL;DR

This review discusses how multi-wavelength imaging reveals debris disk structures, emphasizing dust temperature-based classification to identify signs of multiple low-mass planets beyond the water-ice line.

Contribution

It introduces a dust temperature-based framework for analyzing debris disks and proposes that large gaps between dust belts indicate multiple low-mass planets.

Findings

Warm and cold dust belts are common features in debris disks.

Large gaps between dust belts suggest the presence of multiple low-mass planets.

Debris disk structures inform about planetary system formation and evolution.

Abstract

We review the nearby debris disk structures revealed by multi-wavelength images from Spitzer and Herschel, and complemented with detailed spectral energy distribution modeling. Similar to the definition of habitable zones around stars, debris disk structures should be identified and characterized in terms of dust temperatures rather than physical distances so that the heating power of different spectral type of stars is taken into account and common features in disks can be discussed and compared directly. Common features, such as warm (~150 K) dust belts near the water-ice line and cold (~50 K) Kuiper-belt analogs, give rise to our emerging understanding of the levels of order in debris disk structures and illuminate various processes about the formation and evolution of exoplanetary systems. In light of the disk structures in the debris disk twins (Vega and Fomalhaut), and the current limits on the masses of planetary objects, we suggest that the large gap between the warm and cold dust belts is the best signpost for multiple (low-mass) planets beyond the water-ice line.