The Faintest WISE Debris Disks: Enhanced Methods for Detection and Verification

TL;DR

This study enhances detection methods for faint debris disks around nearby stars using improved WISE data analysis, identifying 107 new disks and expanding the known sample significantly.

Contribution

It introduces refined techniques for detecting faint debris disks, including better confidence thresholds and contamination removal using high-resolution WISE images.

Findings

Identified 19 new debris disk candidates.

Total of 107 debris disks found around 75 pc stars.

Sample size increased by 22% for Hipparcos main-sequence stars.

Abstract

In an earlier study we reported nearly 100 previously unknown dusty debris disks around Hipparcos main sequence stars within 75 pc by selecting stars with excesses in individual WISE colors. Here, we further scrutinize the Hipparcos 75 pc sample to (1) gain sensitivity to previously undetected, fainter mid-IR excesses and (2) to remove spurious excesses contaminated by previously unidentified blended sources. We improve upon our previous method by adopting a more accurate measure of the confidence threshold for excess detection, and by adding an optimally-weighted color average that incorporates all shorter-wavelength WISE photometry, rather than using only individual WISE colors. The latter is equivalent to spectral energy distribution fitting, but only over WISE band passes. In addition, we leverage the higher resolution WISE images available through the unWISE.me image service to identify contaminated WISE excesses based on photocenter offsets among the W3- and W4-band images. Altogether, we identify 19 previously unreported candidate debris disks. Combined with the results from our earlier study, we have found a total of 107 new debris disks around 75 pc Hipparcos main sequence stars using precisely calibrated WISE photometry. This expands the 75 pc debris disk sample by 22% around Hipparcos main-sequence stars and by 20% overall (including non-main sequence and non-Hipparcos stars).