快猫短视频

A YOUNG star not too far from Earth has performed the remarkable trick of
puffing out a spherical cloud of gas. This single event is forcing a rethink on
the whole theory of how stars form.

According to current ideas, every young star sits at the centre of a swirling
disc of gas and dust while at the same time spewing out matter at each pole in a
pair of narrow jets.

But a newly formed star 2000 light years from Earth in the constellation
Cepheus appears to have contradicted the theory by ejecting hot water vapour
evenly in all directions, creating a spherical bubble, say researchers who have
analysed data collected five years ago.

When the team, led by Paul T. P. Ho of the Harvard-Smithsonian Center for
Astrophysics in Massachusetts and Jose Torrelles of the Institute for Space
Studies of Catalonia in Spain, studied microwave emissions from the vapour they
observed a string of bright spots that formed part of a circle roughly
one-and-a-half times as wide as our Solar System. This circle was so nearly
perfect that it had to be the outline of a spherical bubble. The team found it
was expanding at 9 kilometres per second.

The cloud is a puzzle, says Kevin Marvel of the American Astronomical Society
in Washington DC, because jets carry away excess angular momentum and slow
spinning stars. Without such braking the star flings away matter in the disc and
stops growing.

Alan Boss of the Carnegie Institution of Washington says a star that starts
out very massive might just be able to produce a spherical cloud. But
observations of the star in Cepheus suggest that it is not big enough to do
this, says Marvel. All the astronomers agree that they need to identify the star
if they are to make sense of it. 鈥淯ntil they find whatever is at the centre,
it鈥檚 going to be a bit of a mystery,鈥� says Boss.