QUOTE (machi @ Nov 7 2014, 08:51 AM)
It's thermal radiation by dust around that star. Dust is very cold and it radiates most of energy as electromagnetic waves in far infrared and submillimeter parts of the spectra.
Thank you, machi. This is exactly what I was looking for. I went back to a pre-discovery article and finally found a similar statement:
"To observe unambiguous evidence for collapse, we require high spatial and velocity resolution (to map the velocity field across small structures) and high sensitivity (to take advantage of the spatial and velocity resolution). Furthermore, this must be available
at a wavelength at which the collapsing object emits, and at which the surrounding material is transparent."
http://www.almaobservatory.org/en/about-al...lanet-formationIt helps me, at least, to understand that we are seeing dustshine from the colder end of the blackbody spectrum, and that the glow represents dust density, not reflection or excitation from another source, even the core star (our intuitive expectation).