Our Cycle 0 ALMA observations confirmed that the Boomerang Nebula is the coldest known object in the Universe , with a massive high-speed outflow that has cooled significantly below the cosmic background temperature .
Our new CO 1–0 data reveal heretofore unseen distant regions of this ultra-cold outflow , out to \gtrsim 120 , 000 AU .
We find that in the ultra-cold outflow , the mass-loss rate ( \dot { M } ) increases with radius , similar to its expansion velocity ( V ) – taking V \propto r , we find \mbox { $ \dot { M } $ } \propto r ^ { 0.9 - 2.2 } .
The mass in the ultra-cold outflow is \gtrsim 3.3 M _ { \odot } , and the Boomerang ’ s main-sequence progenitor mass is \gtrsim 4 M _ { \odot } .
Our high angular resolution ( \sim 0 \farcs 3 ) CO J=3–2 map shows the inner bipolar nebula ’ s precise , highly-collimated shape , and a dense central waist of size ( FWHM ) \sim 1740 AU \times 275 AU .
The molecular gas and the dust as seen in scattered light via optical HST imaging show a detailed correspondence .
The waist shows a compact core in thermal dust emission at 0.87–3.3 mm , which harbors ( 4 - 7 ) \times 10 ^ { -4 } M _ { \odot } of very large ( \sim mm-to-cm sized ) , cold ( \sim 20 - 30 K ) grains .
The central waist ( assuming its outer regions to be expanding ) and fast bipolar outflow have expansion ages of \lesssim 1925 yr and \leq 1050 yr : the ‘ ‘ jet-lag ’ ’ ( i.e. , torus age minus the fast-outflow age ) in the Boomerang supports models in which the primary star interacts directly with a binary companion .
We argue that this interaction resulted in a common-envelope configuration while the Boomerang ’ s primary was an RGB or early-AGB star , with the companion finally merging into the primary ’ s core , and ejecting the primary ’ s envelope that now forms the ultra-cold outflow .