Galactic Structure Toward the Carina Tangent

TL;DR

This study uses uvbybeta photometry to analyze the Galactic structure toward the Carina arm, revising distances to clusters and identifying new OB associations, thereby enhancing understanding of the region's stellar distribution.

Contribution

It provides revised distances for key clusters and stars, identifies a new OB association, and offers improved measurements of Galactic structure in the Carina tangent region.

Findings

Revised distance of Loden 112 to approximately 1629 pc.

New distance estimate for Wd 2 at about 6698 pc.

Identification of a potential new OB association.

Abstract

This investigation presents a photometric study of the Galactic structure toward the Carina arm tangent. The field is located between 280 deg and 286 deg galactic longitude and -4 deg to 4 deg galactic latitude. All currently available uvbybeta data is used to obtain homogeneous color excesses and distances for more than 260 stars of spectral types O to G. We present revised distances and average extinction for the open clusters and cluster candidates NGC 3293, NGC 3114, Loden 46 and Loden 112. The cluster candidate Loden 112 appears to be a very compact group at a true distance modulus of 11.06 +\- 0.11 (s.e.) (1629 +84,-80 pc), significantly closer than previous estimates. We found other OB stars at that same distance and, based on their proper motions, suggest a new OB association at coordinates 282 deg < l < 285 deg, -2 deg < b < 2 deg. Utilizing BV photometry and spectral classification of the known O-type stars in the very young open cluster Wd 2 we provide a new distance estimate of 14.13 +\-0.16 (s.e.) (6698 +512,-475 pc), in excellent agreement with recent distance determinations to the giant molecular structures in this direction. We also discuss a possible connection between the HII region RCW 45 and the highly-reddened B+ star CPD -55 3036 and provide a revised distance for the luminous blue variable HR Car.