A Trend Between Cold Debris Disk Temperature and Stellar Type: Implications for the Formation and Evolution of Wide-Orbit Planets

TL;DR

This study analyzes 174 cold debris disks around 546 stars, revealing a correlation between disk inner edge temperatures and stellar types, which informs theories of planet formation and migration.

Contribution

It provides the first comprehensive analysis linking debris disk inner edge temperatures to stellar types, challenging temperature-dependent formation models.

Findings

Inner edge temperature correlates with stellar type.

No evidence supports delayed stirring as the cause.

Outward planet migration or formation limits may explain the trend.

Abstract

Cold debris disks trace the limits of planet formation or migration in the outer regions of planetary systems, and thus have the potential to answer many of the outstanding questions in wide-orbit planet formation and evolution. We characterized the infrared excess spectral energy distributions of 174 cold debris disks around 546 main-sequence stars observed by both Spitzer IRS and MIPS. We found a trend between the temperature of the inner edges of cold debris disks and the stellar type of the stars they orbit. This argues against the importance of strictly temperature-dependent processes (e.g. non-water ice lines) in setting the dimensions of cold debris disks. Also, we found no evidence that delayed stirring causes the trend. The trend may result from outward planet migration that traces the extent of the primordial protoplanetary disk, or it may result from planet formation that halts at an orbital radius limited by the efficiency of core accretion.