Accelerating material away from the site of a stellar explosion was found in a star-forming cloud.
This is only the second time that such molecular currents have ever been seen, but it could help astronomers understand how the biggest stars get their lives.
In the 1980s, astronomers discovered something special in the Orion nebula: streams of dense molecular gas, traveling at high speed through space. When these streamers were mapped, they seemed to come from a single point.
Since then, molecular currents have been found in many star-forming regions. They are thought to play an important role in the formation of low-mass stars, carrying away the square moment that would cause a child’s stars to spin themselves.
Orion outflows, however, were one of a kind. Molecular outflow in bipolar low-mass stars; that is, there are only two of them, firing out the other side. The outer edges of Orion were much more numerous … and were also found in an area where much larger stars – more than 10 times the mass of the sun – form.
Connected X-ray, radio and optical imaging of W28, the area’s parent building. (NASA / ROSAT; NOAO / CTIO / PF Winkler et al; NSF / NRAO / VLA / G. Dubner et al.)
Now, we don’t know as much about creating big stars as we do about the smallest ones. Large stellar nurseries are rarer and tend to be more distant, making them harder to see. So astronomers thought that Orion’s currents might give off a few hints.
But the store of the outflows had nothing – there was no big baby star. This could mean a number of explosive situations, such as the merging of two giant baby stars, or gravitational energy released by the formation of a nearby giant binary. But with just one view of its kind, strong governance is difficult.
To try and learn more about this miracle, a team of astronauts led by Luis Zapata of the National Autonomous University of Mexico decided to turn one of our most powerful radio telescopes, the Atacama Large Millimeter / Submillimeter Array (ALMA), at very well known. stellar nursery.
False color image of W28. (NRAO / AUI / NSF and Brogan et al.)
G5.89−0.39, also known as W28 A2, is about 9,752 light-years away. It has a clear, shell-like ultra-compact hydrogen cloud, and powerful molecular sieves. Zapata and his team had previously noticed that six of these filaments appeared to point directly at the center of the hydrogen cloud, but their results were inconclusive.
ALMA cleared the wrong thing. He found thick currents based on the emission wavelength from carbon dioxide and silicon monoxide.
(Zapata et al., ApJL, 2020)
The astronomers were able to identify 34 molecular currents that were moving radically away from the heart of the cloud, accelerating outward. Depending on the distance up to 130 kilometers (80 miles) per second, the outflows are about 1,000 years old; no matter what the explosion they did happened about a thousand years ago.
They are not as powerful as the currents you would expect from a supernova explosion, which occurs when a giant star dies. Moreover, as also observed in the case of Orion, there was no star in the center – just an area of ionic gas, probably due to heating at an explosive event.
If a star (or multiple stars) was associated with the event that triggered the currents, it could have been expelled from the area.
Since big stars always come together in assemblages, such interactions are very common, and that can shed some light on the formation of big stars. If two Protestants came together, it would seem that they would have ended up as one much bigger star.
Based on Orion outflows, the G5.89 outflow, and the small discovery of what might look like streams in a star-forming region called DR-21, the team is predict that these events will happen every 130 years or so. That’s very close to an estimated level of supernova explosions.
The severity of these events, and the length of the outflow rate, may make them very difficult to detect; but, now that we know what to look for and how, astronomers may be able to build a catalog of these events. At the same time, this will help us to understand why they are happening.
“If enough of these streams are found in the future, the union of star records could be an important creation tool of big stars,” Zapata said.
The research was published in Letters of the Astrophysical Journal.