Improved distances to several Galactic OB associations

TL;DR

This study uses uvbybeta photometry to refine distance measurements and analyze the structure of several Galactic OB associations and star-forming regions, revealing their spatial relationships and complexities.

Contribution

It provides improved distance estimates and structural insights for multiple Galactic OB associations using uvbybeta photometry, clarifying their spatial correlations.

Findings

Lac OB1 is at 520 pc and associated with HII region Sh2-126.

Loden 112 is at 1630 pc, linked to OB stars toward Carina.

The Car OB1 field is complex, with parts of the Carina arm projected along the line of sight.

Abstract

Based on uvbybeta photometry we study the structure of several Galactic star-forming fields. Lac OB1 is a compact association at 520+/-20 pc spatially correlated with a region of intense HII emission in Sh2-126. Loden 112 is a compact OB group at 1630+/-82 pc, probably connected to an extended feature of OB stars located toward the Carina tangent. The field toward Car OB1 is complex and likely contains apparent concentrations representing parts of long segments of the Carina arm projected along the line of sight. Within the classical Mon OB2 association we separate a relatively compact group at 1.26 kpc, that is spatially correlated to the Monoceros Loop SN remnant.