WISE Circumstellar Disks in the Young Sco-Cen Association

TL;DR

This study analyzes WISE data for stars in Sco-Cen OB2, revealing that about 41% of BAF-type stars have infrared excesses indicative of circumstellar disks, with excess fraction increasing with membership probability.

Contribution

First to incorporate membership probability in calculating infrared excess fractions for young stars in Sco-Cen OB2.

Findings

41+-5% of Sco-Cen BAF stars have excesses.

Infrared excess fraction increases with membership probability.

B-type stars have smaller excess fractions than A and F-type stars.

Abstract

We present an analysis of the WISE photometric data for 829 stars in the Sco-Cen OB2 association, using the latest high-mass membership probabilities. We detect infrared excesses associated with 135 BAF-type stars, 99 of which are secure Sco-Cen members. There is a clear increase in excess fraction with membership probability, which can be fitted linearly. We infer that 41+-5% of Sco-Cen OB2 BAF stars to have excesses, while the field star excess fraction is consistent with zero. This is the first time that the probability of non-membership has been used in the calculation of excess fractions for young stars. We do not observe any significant change in excess fraction between the three subgroups. Within our sample, we have observed that B-type association members have a significantly smaller excess fraction than A and F-type association members.