Outflows in rho Ophiuchi as Seen with the Spitzer Infrared Array Camera

TL;DR

This study used Spitzer IRAC images to identify and catalog mid-infrared outflows in the rho Ophiuchi cloud, revealing new outflows and their distribution, which suggests a propagation pattern of star formation.

Contribution

The paper presents the first extensive survey of mid-infrared outflows in rho Ophiuchi using IRAC, discovering 13 new outflows and analyzing their spatial distribution.

Findings

Detected 13 new mid-infrared outflows in rho Ophiuchi.

Most outflows are concentrated in the L1688 dense core.

Outflow distribution indicates star formation propagates southeastward.

Abstract

Using the IRAC images from the Spitzer c2d program, we have made a survey of mid-infrared outflows in the rho Ophiuchi molecular cloud. Extended objects that have prominent emission in IRAC channel 2 (4.5 micron) compared to IRAC channel 1 (3.6 micron) and stand out as green objects in the three-color images (3.6 micron in blue, 4.5 micron in green, 8.0 micron in red) are identified as mid-infrared outflows. As a result, we detected 13 new outflows in the rho Ophiuchi molecular cloud that have not been previously observed in optical or near-infrared. In addition, at the positions of previously observed HH objects or near-infrared emission, we detected 31 mid-infrared outflows, among which seven correspond to previously observed HH objects and 30 to near-infrared emission. Most of the mid-infrared outflows detected in the rho Ophiuchi cloud are concentrated in the L1688 dense core region. In combination with the survey results for Young Stellar Objects (YSOs) and millimeter and sub-millimeter sources, the distribution of mid-infrared outflows in the rho Ophiuchi molecular complex hints a propagation of star formation in the cloud in the direction from the northwest to the southeast as suggested by previous studies of the region.