Outflows, Dusty Cores, and a Burst of Star Formation in the North America and Pelican Nebulae

TL;DR

This study maps and analyzes molecular hydrogen outflows in the North America and Pelican Nebulae, revealing active star formation, complex outflow structures, and recent starburst activity in dense dust cores.

Contribution

It provides detailed observations of outflows and shocks in the nebulae, introduces an activity index for cloud evolution, and links outflow activity to star formation stages.

Findings

Hundreds of shocks from over 50 outflows identified.

Discovery of a large, 1.6 parsec outflow from a massive clump.

Evidence of recent starburst activity and complex outflow morphologies.

Abstract

We present observations of near-infrared 2.12 micro-meter molecular hydrogen outflows emerging from 1.1 mm dust continuum clumps in the North America and Pelican Nebula (NAP) complex selected from the Bolocam Galactic Plane Survey (BGPS). Hundreds of individual shocks powered by over 50 outflows from young stars are identified, indicating that the dusty molecular clumps surrounding the NGC 7000 / IC 5070 / W80 HII region are among the most active sites of on-going star formation in the Solar vicinity. A spectacular X-shaped outflow, MHO 3400, emerges from a young star system embedded in a dense clump more than a parsec from the ionization front associated with the Pelican Nebula (IC 5070). Suspected to be a binary, the source drives a pair of outflows with orientations differing by 80 degrees. Each flow exhibits S-shaped symmetry and multiple shocks indicating a pulsed and precessing jet. The `Gulf of Mexico' located south of the North America Nebula (NGC 7000), contains a dense cluster of molecular hydrogen objects (MHOs), Herbig-Haro (HH) objects, and over 300 YSOs, indicating a recent burst of star formation. The largest outflow detected thus far in the North America and Pelican Nebula complex, the 1.6 parsec long MHO 3417 flow, emerges from a 500 Solar mass BGPS clump and may be powered by a forming massive star. Several prominent outflows such as MHO 3427 appear to be powered by highly embedded YSOs only visible at a wavelength > 70 micro-meters. An `activity index' formed by dividing the number of shocks by the mass of the cloud containing their source stars is used to estimate the relative evolutionary states of Bolocam clumps. Outflows can be used as indicators of the evolutionary state of clumps detected in mm and sub-mm dust continuum surveys.