A Spitzer Census of Star Formation Activity in the Pipe Nebula

TL;DR

This study uses Spitzer mid-infrared data to conduct a comprehensive census of star formation in the Pipe Nebula, revealing an extremely low level of star formation activity with only 18 candidate YSOs identified.

Contribution

First detailed mid-infrared survey of the entire Pipe Nebula quantifying its very low star formation activity and identifying candidate young stellar objects.

Findings

Only 18 candidate YSOs found in the entire cloud.

Star formation efficiency is approximately 0.06%.

Most YSOs are associated with the Barnard 59 cluster.

Abstract

The Pipe Nebula, a large nearby molecular cloud lacks obvious signposts of star formation in all but one of more than 130 dust extinction cores that have been identified within it. In order to quantitatively determine the current level of star formation activity in the Pipe Nebula, we analyzed 13 square degrees of sensitive mid-infrared maps of the entire cloud, obtained with the Multiband Imaging Photometer for Spitzer (MIPS) at wavelengths of 24 micron and 70 micron to search for candidate Young Stellar Objects (YSOs) in the high-extinction regions. We argue that our search is complete for class I and typical class II YSOs with luminosities of Lbol~0.2 Lo and greater. We find only 18 candidate YSOs in the high-extinction regions of the entire Pipe cloud. Twelve of these sources are previously known members of a small cluster associated with Barnard 59, the largest and most massive dense core in the cloud. With only six candidate class I and class II YSOs detected towards extinction cores outside of this cluster, our findings emphatically confirm the notion of an extremely low level of star formation activity in the Pipe Nebula. The resulting star formation efficiency for the entire cloud mass is only ~0.06 %.