Cold debris: An artist's impression of an icy planet orbiting an alien star.
Credit: European Southern Observatory
Signpost of planet formation
However, Australian astrophysicist Chris Tinney from the University of New South Wales in Sydney, said the researchers' conclusion was "going out on a limb".
"My feeling is they over-egged the omelette a little bit in saying that A-type stars produce icy planets," said Tinney. "They've demonstrated A-type stars have these 24 micrometre emissions – that doesn't necessarily mean they produce icy planets. Many things in space have cold dust, it doesn't necessarily mean that icy planets are stirring things up."
Currie argued, though, that their method is a standard one.
He added that "the abundance of water ice [in the emissions] is very high compared to solids that condense out at higher temperatures. Thus, the debris responsible for emitting the radiation we see must be icy. Because the debris are fragments of larger bodies broken off during planet-forming collisions, the debris emission is a signpost of icy planet formation."
