Bibcode
López, R.; Acosta-Pulido, J. A.; Gomez-Velarde, G.; Estalella, R.; Carrasco-González, C.
Bibliographical reference
Astronomy and Astrophysics, Volume 523, id.A16
Advertised on:
11
2010
Journal
Citations
4
Refereed citations
4
Description
Context. The dark cloud Lynds 723 (L723) is a low-mass star-forming
region where one of the few known cases of a quadrupolar CO outflow has
been reported. Two recent works have found that the radio continuum
source VLA 2, towards the centre of the CO outflow, is actually a
multiple system of young stellar objects (YSOs). Several line-emission
nebulae that lie projected on the east-west CO outflow were detected in
narrow-band Hα and [S ii] images. The spectra of the knots are
characteristic of shock-excited gas (Herbig-Haro spectra), with
supersonic blueshifted velocities, which suggests an optical outflow
also powered by the VLA 2 YSO system of L723. Aims: Our aim is to
study L723 in the near-infrared and look for line-emission nebulae
associated with the optical and CO outflows. Methods: We imaged a
field of ~5' × 5' centred on HH 223, which includes the whole
region of the quadrupolar CO outflow with narrow-band filters centred on
the [Fe ii] 1.644 μm and H2 2.122 μm lines, together
with off-line Hc and Kc filters. The [Fe ii] and
H2 line-emission structures were identified after extracting
the continuum contribution, if any. Their positions were determined from
an accurate astrometry of the images. Results: The H2
line-emission structures appear distributed over a region of 5.5 arcmin
(~0.5 pc for a distance of 300 pc) at both sides of the VLA 2 YSO
system, with an S-shape morphology, and are projected onto the east-west
CO outflow. Most of them were resolved in smaller knotty substructures.
The [Fe ii] emission only appears associated with HH 223. An additional
nebular emission from the continuum in Hc and Kc
appears associated with HH 223-K1, the structure closest to the VLA 2
YSO system, and could be tracing the cavity walls. Conclusions:
We propose that the H2 structures form part of a large-scale
near-infrared outflow, which is also associated with the VLA 2 YSO
system. The current data do not allow us to discern which of the YSOs of
VLA 2 is powering this large scale optical/near-infrared outflow.
Based on observations made with LIRIS at the 4.2 m Williams Herschel
Telescope operated at the Observatorio del Roque de los Muchachos of the
Instituto de Astrofísica de Canarias.Fits files of Table 1 are
available at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)
or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/523/A16
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