An extraordinary outburst in the massive protostellar system NGC6334I-MM1: quadrupling of the millimeter continuum

Understand

Based on sub-arcsecond Atacama Large Millimeter/submillimeter Array (ALMA) and Submillimeter Array (SMA) 1.3 mm continuum images of the massive protocluster NGC 6334I obtained in 2015 and 2008, we find that the dust emission from MM1 has increased by a factor of 4.0$\pm$0.3 during the intervening years, and undergone a significant change in morphology.

• The continuum emission from the other cluster members (MM2, MM4 and the UCHII region MM3 = NGC 6334F) has remained constant.
• Long term single-dish maser monitoring at HartRAO finds that multiple maser species toward NGC 6334I flared beginning in early 2015, a few months before our ALMA observation, and some persist in that state.
• New ALMA images obtained in 2016 July-August at 1.1 and 0.87 mm confirm the changes with respect to SMA 0.87 mm images from 2008, and indicate that the (sub)millimeter flaring has continued for at least a year.