[AstroNet] Birth of Planets Revealed in Astonishing Detail in ALMA's 'Best Image Ever'

[Sam Rametse]

https://public.nrao.edu/static/pr/planet-formation-alma.html





Astronomers have captured the best image ever of planet formation around an
infant star as part of the testing and verification process for the Atacama
Large Millimeter/submillimeter Array’s (ALMA) new high-resolution
capabilities.

This revolutionary new image reveals in astonishing detail the
planet-forming disk surrounding HL Tau, a Sun-like star located
approximately 450 light-years from Earth in the constellation Taurus.

ALMA uncovered never-before-seen features in this system, including
multiple concentric rings separated by clearly defined gaps. These
structures suggest that planet formation is already well underway around
this remarkably young star.

"These features are almost certainly the result of young planet-like bodies
that are being formed in the disk. This is surprising since HL Tau is no
more than a million years old and such young stars are not expected to have
large planetary bodies capable of producing the structures we see in this
image," said ALMA Deputy Director Stuartt Corder.

All stars are believed to form within clouds of gas and dust that collapse
under gravity. Over time, the surrounding dust particles stick together,
growing into sand, pebbles, and larger-size rocks, which eventually settle
into a thin protoplanetary disk where asteroids, comets, and planets form.

Once these planetary bodies acquire enough mass, they dramatically reshape
the structure of their natal disk, fashioning rings and gaps as the planets
sweep their orbits clear of debris and shepherd dust and gas into tighter
and more confined zones.

The new ALMA image reveals these striking features in exquisite detail,
providing the clearest picture to date of planet formation. Images with
this level of detail were previously only seen in computer models and
artist concepts. ALMA, living up to its promise, has now provided direct
proof that nature and theory are very much in agreement.

"This new and unexpected result provides an incredible view of the process
of planet formation. Such clarity is essential to understand how our own
Solar System came to be and how planets form throughout the Universe," said
Tony Beasley, director of the National Radio Astronomy Observatory (NRAO)
in Charlottesville, Virginia, which manages ALMA operations for astronomers
in North America.

HL Tau is hidden in visible light behind a massive envelope of dust and
gas. Since ALMA observes at much longer wavelengths, it is able to peer
through the intervening dust to study the processes right at the core of
this cloud. "This is truly one of the most remarkable images ever seen at
these wavelengths. The level of detail is so exquisite that it's even more
impressive than many optical images. The fact that we can see planets being
born will help us understand not only how planets form around other stars
but also the origin of our own Solar System," said NRAO astronomer Crystal
Brogan.

ALMA's new high-resolution capabilities were achieved by spacing the
antennas up to 15 kilometers apart. This baseline at millimeter wavelengths
enabled a resolution of 35 milliarcseconds, which is equivalent to a penny
as seen from more than 110 kilometers away.

"Such a resolution can only be achieved with the long baseline capabilities
of ALMA and provides astronomers with new information that is impossible to
collect with any other facility, including the best optical observatories,"
noted ALMA Director Pierre Cox.

These long baselines fulfill one of ALMA’s major objectives and mark an
impressive technological and engineering milestone. Future observations at
ALMA's longest possible baseline of 16 kilometers will produce even clearer
images and continue to expand our understanding of the cosmos.

"This observation illustrates the dramatic and important results that come
from NSF supporting world-class instrumentation such as ALMA," said Fleming
Crim, the National Science Foundation assistant director for Mathematical
and Physical Sciences. "ALMA is delivering on its enormous potential for
revealing the distant Universe and is playing a unique and transformational
role in astronomy."
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