Stars are formed inside molecular clouds as they collapse and divide into smaller chunks of burning hydrogen. But to actually see these stellar nurseries in detail and understand how they work has proved tricky in the past. This is because these molecular clouds, made up of interstellar dust and gas, can usually be observed only in the 2D perspective we have from Earth.
However, a pair of researchers from the University of Crete in Greece has managed to make a 3D model of the interstellar cloud Musca using nothing but sound, Space.com reports.
This giant space cloud lies about 570 light-years from Earth, in the Southern Cross, or Crux, constellation. Astronomers Aris Tritsis and Konstantinos Tassis took a peek at Musca using the European Space Agency’s Herschel Space Observatory and uncovered that the interstellar cloud “sings” through magnetic waves that vibrate inside it at resonant frequencies.
Musca’s “song” — a bunch of magnetohydrodynamic waves encoded in hair-like striations that are produced as the waves propagate through the cloud — was revealed by far-infrared observations of the isolated cloud.
By “listening” to the cloud’s vibrations and studying the spacing of the striations, the astronomers were able to reconstruct Musca’s 3D structure — a first in the study of interstellar clouds.
Commenting on the importance of their discovery, Tassis explained that it could shed more light on the process of star formation.
“The 3D structure of interstellar clouds has been, for decades now, the ‘holy grail’ in figuring out how clouds break up into smaller fragments, and how these fragments go on to form stars.”
The pair detailed Musca’s 3D model and the process of how it came to be in a study published yesterday in the journal Science. Going forward, the astronomers plan to find out if there are more “singing” interstellar clouds out there that could help unlock the mystery of how stars are formed.
By finally recreating the 3D structure of an interstellar cloud, scientists can now hope to understand how magnetism, gravity, and turbulence interact inside these molecular clouds and lead to star formation.
— NASA world (@NASAworld1) May 10, 2018
But this first-ever 3D view of Musca is important in more ways than one. For instance, the 3D reconstruction unveiled a surprising detail about the giant space cloud. Although it was previously believed that Musca has a needle-like shape that looks like an elongated filament, it turned out that it’s actually flat like a pancake when observed edge-on.
A close look at the cloud’s striations revealed that their pattern is consistent with a large sheet and not a filament. Since Musca’s striations are the imprint of its magnetic waves, which in turn reflect the cloud’s shape, the pair concluded that the “singing” interstellar cloud is pancake-shaped.
This can offer a clue about what type of stars are forming inside it and how many can be created by the magnetic force that gives Musca its pancake shape.
According to Science Magazine, the 3D model also allowed Tritsis and Tassis to calculate the Musca’s size and determine that the interstellar cloud is roughly 26 light-years long and 20 light-years wide.
The two astronomers hope that their study will help other researchers use the same technique to investigate many other interstellar clouds and eventually get to the bottom of how stars come into existence.