News on two jets in Lupus 3^⋆

¹ ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
e-mail: fcomeron@eso.org
² Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía 3, 18008 Granada, Spain
e-mail: matilde@iaa.es

Received: 23 October 2010
Accepted: 24 January 2011

Abstract

Context. Jets from solar-type and low-mass stars are typical manifestations of stellar youth. Shocks along these jets produce visible, generally fast-moving Herbig-Haro objects whose proper motions are easily measured in nearby star-forming regions using images taken just a few years apart. Herbig-Haro objects have now been observed in association with objects close to the substellar boundary.

Aims. We present second-epoch observations of the central area of the Lupus 3 star-forming region that include two of its most interesting Herbig-Haro systems. One is HH 228, produced by the classical T Tauri star Th 28 (=Sz 102), whereas the other is HH 600, which has its origin in the very low-mass star Par-Lup3-4.

Methods. Narrow-band imaging through filters centered on the Hα and the [SII] lines was obtained with the FORS2 instrument at the Very Large Telescope (VLT) in mid-2010. The images obtained were compared to others obtained in early 2003, leading to the discovery of HH 600.

Results. New Herbig-Haro objects are found at large distances from Th 28 and to be associated with it, representing an extension of the HH 228 jet to a projected distance of 0.32 pc from Th 28. The farthest Herbig-Haro object is HH 989, whose possible relationship with Th 28 had been already suggested in a previous study but is now kinematically confirmed. We find other likely Herbig-Haro objects whose proper motions are less indicative of a connection with Th 28, but which may be caused by oblique shocks near the outer walls of its jet. For the HH 600 jet, the knot discovered by ourselves in 2003 to the southeast of Par-Lup3-4 is found to have clearly moved and faded. Using high resolution spectroscopy obtained in 2003 and the proper motion that we can measure now, we determine a spatial velocity of 170 ± 30 km s^-1. The northwestern jet is found to have grown in prominence in the intervening years. The possible relationship of other Herbig-Haro objects in the region with Th 28, Par-Lup3-4, and other young stellar objects in the area is discussed.