The clearest ever image of planets forming
around an infant star has been taken by the
Alma radio telescope.
In a vast disc of dust and gas, dark rings are
clearly visible: gaps in the cloud, swept clear by
brand new planets in orbit.
The sun-like star at the centre, HL Tau, is less than
a million years old and is 450 light years from
Earth in the constellation Taurus.
The image was made possible by Alma's new high-
resolution capabilities.
Because the process of planet formation takes
place in the midst of such a huge dust cloud, it
can't be observed using visible light.
Alma, the Atacama Large Millimeter/submillimeter
Array, has snapped the impressive new image
using much longer wavelengths, which it detects
by comparing the signal from multiple antennas
up to 15km apart.
To test out its latest high-resolution capability,
only in operation since September, Alma scientists
pointed the antennas at HL Tau. They found
themselves looking at a "protoplanetary disc" in
more detail than ever before.
"I think it's phenomenal," said Dr Aprajita Verma,
an astrophysicist at the University of Oxford.
"This shows how exciting Alma is going to be - it's
going to be an incredible instrument."

Prof Tim de Zeeuw is director general of the
European Southern Observatory, one of several
organisations involved in Alma. He said: "Most of
what we know about planet formation today is
based on theory. Images with this level of detail
have up to now been relegated to computer
simulations or artist's impressions."
Dr Verma agreed that the image was a significant
new piece of evidence - particularly because the
star HL Tau is very young.
"I think the big result is that you might have
expected just a smooth disc," she told the BBC.
"But you're really seeing multiple rings - and
where it's darker, that's where you've cleared the
material already in the disc."
The whole process is happening faster than we
would have predicted from existing data, Dr
Verma explained.
"It means that things are coagulating. It's really a
planetary system, that you're seeing at a very
early time.
"These rings will form planets, asteroids, comets...
And eventually as the star evolves, this will cool
and settle and there will be more clearing and
more individual objects, just like we see in our
solar system."


Source-: m.bbc.com/news/science-environment-29932609