ABSTRACT
We present far-infrared observations of Monoceros R2 (a giant molecular cloud at approximately 830 pc distance, containing several sites of active star formation), as observed at 70 µm, 160 µm, 250 µm, 350 µm, and 500 µm by the Photodetector Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging Receiver (SPIRE) instruments on the Herschel Space Observatory as part of the Herschel imaging survey of OB young stellar objects (HOBYS) Key programme. The Herschel data are complemented by SCUBA-2 data in the submillimetre range, and WISE and Spitzer data in the mid-infrared. In addition, C18O data from the IRAM 30-m Telescope are presented, and used for kinematic information. Sources were extracted from the maps with getsources, and from the fluxes measured, spectral energy distributions were constructed, allowing measurements of source mass and dust temperature. Of 177 Herschel sources robustly detected in the region (a detection with high signal-to-noise and low axis ratio at multiple wavelengths), including protostars and starless cores, 29 are found in a filamentary hub at the centre of the region (a little over 1% of the observed area). These objects are on average smaller, more massive, and more luminous than those in the surrounding regions (which together suggest that they are at a later stage of evolution), a result that cannot be explained entirely by selection effects. These results suggest a picture in which the hub may have begun star formation at a point significantly earlier than the outer regions, possibly forming as a result of feedback from earlier star formation. Furthermore, the hub may be sustaining its star formation by accreting material from the surrounding filaments.
ABSTRACT
Analysis of 36 records of the rarely encountered moray Gymnothorax polyuranodon indicate that juveniles and adults inhabit fresh and mildly brackish habitats (salinity < 5) in streams of the Australian Wet Tropics Eighty-one per cent of these records were from freshwater streams and collectively demonstrate that this species inhabits fresh water throughout all seasons. A survey of fish researchers, each with at least 100 h of field experience in Australia's Wet Tropics, revealed that 33% of researchers working in fresh waters (nine of 27 researchers) had encountered the species and 15% of researchers with substantial experience working in estuaries (two of 13 researchers) had encountered the species. The species was not sampled or observed in the nearshore marine environment. The only record of an elver of this species was, however, found in an estuary at a salinity of 33·4. This preliminary evidence suggests adult G. polyuranodon occupy freshwater habitats, but further research is required to understand the complete life cycle, including movements, habitat use and reproductive ecology of the species.
