Orion Outlying Clouds

TL;DR

This paper reviews the properties, star formation activity, and associated phenomena of the Orion outlying clouds, emphasizing their unique features and potential triggered star formation due to nearby massive stars.

Contribution

It provides a comprehensive overview of the Orion outlying clouds, including their properties, star formation evidence, and related phenomena, highlighting new insights into their role in star formation.

Findings

Many outlying clouds show ongoing star formation.

Star formation may be triggered by Orion OB association stars.

Presence of outflows and Herbig-Haro objects in these clouds.

Abstract

In this chapter we review the properties of the Orion outlying clouds at b < -21 degrees. These clouds are located far off the Orion giant molecular cloud complex and are in most cases small cometary-shaped clouds, with their head pointing back towards the main Orion clouds. A wealth of data indicate that star formation is ongoing in many of these clouds. The star formation in these regions might have been triggered due to the strong impact of the massive stars in the Orion OB association. Some of the clouds discussed here may be part of the Orion-Eridanus bubble. An overview on each individual cloud is given. A synthesis of the Pre-Main Sequence stars discovered in these clouds is presented. We also discuss the millimeter and centimeter data and present a review of the outflows and Herbig-Haro objects so far discovered in these clouds.