A wide-field near-infrared H₂ 2.122 μm line survey of the Braid Nebula star formation region in Cygnus OB7^⋆

¹ Max-Plank-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
e-mail: tkhanzadyan@mpifr-bonn.mpg.de
² Joint Astronomy Centre, 660 N. A‘ohōkū Place, University Park, Hilo, HI 96720, USA
³ Astrophysics Division, NASA HQ, 300 E Street SW, Mail Stop 3Y28, Washington, DC 20546, USA
⁴ Institute for Astronomy, University of Hawaii, 640 N. A‘ohōkū Place, Hilo, HI 96720, USA
⁵ Centre for Astrophysics & Planetary Science, School of Physical Sciences, The University of Kent, Canterbury CT2 7NH, UK
⁶ V. A. Ambartsumyan Byurakan Astrophysical Observatory, 0213 Aragatsotn reg., Armenia
⁷ NRC Herzberg Institute of Astrophysics 5071 West Saanich Road Victoria, British Columbia, V9E 2E7, Canada
⁸ Subaru Telescope, National Astronomical Observatory of Japan, 650 N. A‘ohōkū Place, Hilo, HI 96720, USA
⁹ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

Received: 28 February 2012
Accepted: 27 April 2012

Abstract

Context. Outflows and jets are the first signposts of ongoing star formation processes in any molecular cloud, yet their study in optical bands provides limited results due to the large extinction present. Near-infrared unbiased wide-field observations in the H₂ 1−0 S(1) line at 2.122 μm alleviates the problem, enabling us to detect more outflows and trace them closer to their driving sources.

Aims. As part of a large-scale multi-waveband study of ongoing star formation in the Braid Nebula star formation region, we focus on a one square degree region that includes Lynds Dark Nebula 1003 and 1004. Our goal is to find all of the near-infrared outflows, uncover their driving sources and estimate their evolutionary phase.

Methods. We use near-infrared wide-field observations obtained with WFCAM on UKIRT, in conjunction with previously-published optical and archival MM data, to search for outflows and identify their driving sources; we subsequently use colour − colour analysis to determine the evolutionary phase of each source.

Results. Within a one square degree field we have identified 37 complex MHOs, most of which are new. After combining our findings with other wide-field, multi-waveband observations of the same region we were able to discern 28 outflows and at least 18 protostars. Our analysis suggests that these protostars are younger and/or more energetic than those of the Taurus-Auriga region. The outflow data enable us to suggest connection between outflow ejection and repetitive FU Ori outburst events. We also find that star formation progresses from W to E across the investigated region.