4. VLA Observations: a close binary
A small 3.6 cm radio continuum jet was detected around the source by Rodríguez & Reipurth (1994). For their 1992 observations, 0539-057 was used as the phase calibrator. For our newer 1994 and 1996 data presented here we used 0550+032. In 1996 we made observations of both phase calibrators to accurately align the 1992 data with the 1994 and 1996 data. The final alignment of all data is relative to 0550+032. In the upper panel of Fig. 3, we show a map made with natural weighting of the VLA 1 source, identical to star A discussed previously. The source shows, in addition to an elongation along the E-W direction, fainter extensions in the N-S direction, suggesting a quadrupolar morphology.
To enhance the angular resolution of our image, we did a maximum entropy reconstruction using the task VTESS of AIPS, the software package of NRAO. This image is shown in the lower panel of Fig. 3, where the quadrupolar morphology of the source becomes even more evident. The VLA data is suggestive of a quadrupolar jet, with a common origin within (50 AU). This is consistent with the fact that star A seen in the F205W image is perfectly circular, with no evidence for a companion. This distance is similar to the separation of the binary disk system in L1551 IRS5 (Rodríguez et al. 1998). However, in the case of L1551 IRS5 the jets are approximately parallel, while in HH 111 the jets are orthogonal. The PA of the main radio jet is 277o (the same as for the optical HH 111 jet), and the smaller side jet has a PA = 184o. Presumably this little radio jet may be associated with the H2 flow HH 121, although the flow axes are not precisely the same (Gredel & Reipurth 1993,1994).
The 3.6 cm maps show an additional faint, unresolved source (VLA 2) to the NW of VLA 1 (outside Fig. 3) with a flux density of 205 µJy at the position listed in Table 1. As mentioned in Sect. 3, this is a radio counterpart to star B. Our detection at 3.6 cm shows that this star also has outflow activity.
© European Southern Observatory (ESO) 1999
Online publication: December 2, 1999