Optical imaging of L723: the structure of HH 223

¹ Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona, Spain e-mail: [rosario;robert.estalella]@am.ub.es
² Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain e-mail: ggv@ll.iac.es
³ Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Av. Víctor Balaguer s/n, 08800 Vilanova i la Geltrú, Spain e-mail: angels.riera@upc.es

Received: 10 March 2006
Accepted: 23 March 2006

Abstract

Aims.We imaged the Lynds 723 dark nebula (L723) with the aim of studying the morphology of the Herbig-Haro object HH 223 and other line-emission nebula detected in the region.

Methods.We obtained deep narrow-band images in the Hα and [SII] lines and in the continuum nearby Hα of a field of of the L723 dark nebula centered on HH 223.

Results.The Hα and [SII] images reveal the detailed morphology of HH 223, unresolved in previous optical images. Both images show a quite complex knotty, wiggling structure embedded in a low-emission nebula. Comparison between the [SII] and Hα fluxes of the knots are indicative of variations in the excitation conditions through HH 223. In addition, several other faint nebula are detected in Hα a few arcmin to the SE and to the NW of HH 223, all of them lying projected onto the east-west pair of lobes of the quadrupolar CO outflow. Comparison between the Hα and the continuum images confirms the HH-like nature of the Vrba object V83, while the Vrba objects V84 and V85 are identified as faint field stars.