Simba observations of the keyhole nebula

Abstract

We report observations made with the SIMBA bolometer at SEST to measure the 1.2 mm continuum emission toward the Keyhole nebula. We have detected 1.2 mm emission toward the ionized gas filaments of the Car II radio source that is attributed to thermal free-free emission. Several compact 1.2 mm emission sources have also been identified and found to correspond to bright-rimmed molecular globules. Under the assumption that for these sources the 1.2 mm emission corresponds to dust, we find mass estimates in the range 3–19 M , which are consistent with previous molecular line measurements. The data also yield new 1.2 mm flux measurements at two different epochs during the cyclic brightness variation of Carinae. No emission was detected toward the trademark dark keyhole of the nebula, consistent with it being cool molecular gas situated at the outskirts of the H ii region.