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Jackson et al.
have combined data from the Stratospheric Observatory for Infrared Astronomy (SOFIA) with
ATCA and Mopra data to study a bright photodissociation region (PDR) associated with an ionized
bubble located in the Nessie Nebula.
The Nessie Nebula is a filamentary infrared dark cloud (IRDC)
that is unusually long and thin, with a length of at least 250 light years.
The combined data reveals a classic photodissociation region structure, with a uniform progression from
ionized gas, to photodissociated gas, and to molecular gas from the bubble’s interior to its exterior.
The figure above shows multi-frequency maps of the western portion of the Nessie Bubble.
The blue contours are the ATCA 24 GHz radio continuum, which trace ionized gas.
The green contours are the SOFIA [C II] line data, which trace photo-dissociation regions around bright stars.
The grayscale and gray contours are ATCA ammonia (1,1) line emission, which trace colder molecular gas.
The gold contours are the ATCA ammonia (3,3) transition, which trace warmer molecular gas.
The yellow/black square shows the location of the NH3 (3,3) maser.
A luminous young stellar object, in the centre of the image, is located precisely where
the expanding ionized PDR bubble strikes the Nessie filament, and where there is evidence of shocks,
indicating an interaction between the bubble and the filament.
This strongly suggests that the interaction of the
expanding bubble with its parental dense filament has triggered star formation.
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