Detection of a branching-off feature from the Cygnus-Orion arm in the direction of Carina

Abstract

A program is presented for the study of faint young open clusters in the anticenter direction of the Galaxy with the aim of using these clusters as spiral arm tracers. Twelve open clusters are selected for observation. Four of the clusters (OC1 585, 674, 692, and 715) are clearly located along the Orion-Cygnus arm, while one cluster, OC1 798, is a definite member of the Sagittarius-Carina arm. Four of the remaining clusters (OC1 427, 497, 501, and 556) are found in the outer Perseus region, substantiating the existence of the outer Perseus spiral feature. This outer feature appears to be merging with the Orion-Cygnus arm where OC1 694 is located, with its distance from the sun being about 6.5 kpc. The location of OC1 762, along with the presence of two already known clusters at positions along with those of OC1 692 and OC1 715, give an indication of a feature which is branching off from the Orion-Cygnus arm and extending toward the Carina constellation.