Herbig-Haro flows and molecular outflows in the HH 56/57 region
Received 21 March 1996 / Accepted 3 January 1997
A study at optical, infrared and mm wavelengths has been carried out of the Sa 187 cloud in the southern constellation of Norma, which harbors the HH 56 and 57 flows. CCD images of HH 56 show that it has a fine bow shock morphology. Along the line defined by HH 56 and its energy source Re 13 we have found a faint HH object, HH 56N, to the north, and another bow shock, HH 56S, to the south, making HH 56 a large (0.76 pc in projection) bipolar HH flow. Recent CCD images of HH 57 compared to earlier ones show structural variability of the reflection nebula surrounding the FU Orionis driving source V346 Nor. Infrared photometry of V346 Nor collected over a decade shows an irregular variability in J and H, and a gradual brightening in K, L and M, suggesting that the FU Orionis eruption may not yet have peaked. Sensitive high-resolution K-band spectra of V346 Nor have revealed weak emission in the first overtone bands of CO, making it the first FUor known to show CO emission. Extensive 12 CO, 13 CO and CS mm-observations are used to describe the molecular environment of the HH sources. We present detailed 12 CO maps of two large molecular outflows, each one centered on one of the HH sources and co-axial with their associated HH flows. The outflow lobes coincide with visible cavities, outlined against the rich background star fields, in the surrounding molecular cloud. Finally, we identify two young IRAS sources in the extended tail of the Sa 187 cloud and present a 12 CO map of one or two associated small molecular outflows.
Key words: ISM: HH 56/57 ISM: jets and outflows reflection nebulae stars: pre-main sequence Infrared: ISM: lines and bands radio lines: ISM
Send offprint requests to: B. Reipurth
© European Southern Observatory (ESO) 1997
Online publication: April 6, 1998