You might already be aware of the snow lines and tree lines that exist on Earth as indicators of altitude and climate patterns, but did you know this feature can also be observed on a grand scale in the formation of young star systems?
On a cosmic level, the water snowline is the point along a star's protoplanetary disk where the temperature and pressure is low enough for water to transform from gas into ice. (The liquid phase is skipped due to the lack of pressure.)
Also known as a frostline, this marker is usually too close to a young star for astronomers to study it. However, scientists at the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile were recently given an unprecedented look at the phenomenon after V883 Orionis, a young star located 1,350 light-years away, experienced a staggering flare up in both luminosity and temperature.
According to a statement by the National Radio Astronomy Observatory, "heat from a young sun-like star prevents water molecules from freezing within a radius of about three astronomical units, around 450 million kilometers, from the star. (An astronomical unit – AU – is the average distance from the Earth to the sun.) Beyond that point, known as the snowline, water condenses to form a layer of ice on dust grains and other particles."
As a result of V883's powerful flare-up, the star's snowline has been pushed outward by a whopping 40 AU. That's an increase of 6 billion kilometers — which is about the same distance at which Pluto orbits the sun.
In the diagram below, you can compare the star's snowline with the orbital distances of Neptune and Pluto:
Thanks to the sudden flare that pulled back the curtain on snowlines, scientists have gained a greater understanding of not only V883 but also the origins our own solar system.
The position of the snowline plays a major role in determining what type
of planets eventually form along the protoplanetary plane. Generally, the warmer inner ring is
responsible for producing smaller, rockier planets like Earth, while any
planets formed past the snowline develop into gas giants like Jupiter.
"The distribution of water ice around a young star is fundamental to
planet formation and even the development of life on Earth," said Zhaohuan Zhu, an astronomer who served as co-author of the study. "ALMA’s
observation sheds important light on how and where this happens in
protoplanetary disks when young planets are still forming. We now have direct evidence that a frosty region conducive to planet
formation exists around other stars."