Scientists use ALMA telescope to reveal the “secret hug” phase of stars, which will have far-reaching effects

Unlike our sun, most stars have a companion star. Sometimes, the two stars are so close that one of them swallows the other-having a profound effect. When a team of astronomers led by scientists from Chalmers University of Technology used the ALMA telescope to study 15 unusual stars, they were surprised to find that they had all gone through this stage recently. This discovery is expected to give new insights into the most compelling phenomena in the sky-as well as life, death and rebirth in stars.

Using the huge ALMA telescope located in Chile, a team of scientists led by Chalmers University of Technology studied 15 unusual stars in our Milky Way galaxy, the nearest of which is 5000 light years away from the Earth. Their measurement results show that all stars are binary star systems, and they have recently gone through a rare stage, which is little known but is thought to cause many other astronomical phenomena. Their results were published this week in the scientific journal “Natural Astronomy”.

By pointing ALMA’s antenna at each star and measuring the light of different molecules close to each star, the researchers hope to find clues about their background. These stars, nicknamed “water fountains”, are well known by astronomers because of the intense light from water molecules–produced by unusually dense and fast-moving gas.

ALMA is located at an altitude of 5,000 meters in Chile. It is sensitive to light with a wavelength of about one millimeter (not visible to the naked eye), but it is ideal for looking through the interstellar dust clouds of the Milky Way to dust-shrouded stars.

“We are very curious about these stars because they seem to be blowing large amounts of dust and gas into space, some in the form of jets at speeds of up to 1.8 million kilometers per hour.” said Theo Khouri, the first author of the new study: “We thought We may find clues about how these jets are produced, but we find far more than these.”

At most half of the star’s total mass is lost

Scientists used telescopes to measure the characteristics of carbon monoxide molecules in the light of stars and compared the signals from different atoms (isotopes) of carbon and oxygen. Unlike its “sister” molecular carbon dioxide, carbon monoxide is relatively easy to find in space and is the favorite tool of astronomers.

“Due to the exquisite sensitivity of ALMA, we were able to detect very weak signals of several different molecules in the gas ejected by these stars. When we carefully observed the data, we saw details that we really didn’t expect to see. “Theo Khouri said.

Observations confirm that these stars have been blown away from their outer layers. But the ratio of different oxygen atoms in the molecule suggests that these stars are not as extreme as they seem in another respect. Team member Wouter Vlemmings, an astronomer at Chalmers University of Technology, explained: “We realized that these stars are in At the beginning of their lives, they had the same mass as the sun, or only a few times more. Now, our measurements show that they have thrown out 50% of their total mass in just the past few hundred years. It must be on them. A very dramatic thing happened.”

Why does such a small star lose so much mass so quickly? The scientists concluded that the evidence points to an explanation. These are binary star systems, and they have all just gone through a stage in which two stars share the same atmosphere-one star is completely swallowed by the other star.

“At this stage, the two stars move together in the form of a cocoon. This stage, which we call the’co-wrapped’ stage, is really short and lasts only a few hundred years.” said team member Daniel Tafoya: ” From an astronomical point of view, it ended in a blink of an eye.”

Most stars in a binary star system just revolve around a common center of mass. However, these stars share the same atmosphere. For a star, this may be a life-changing experience, and may even lead to the complete merger of the stars.

Clues to the future

Scientists believe that this stage can lead to some of the most spectacular phenomena in the sky. Theo Khouri explained that understanding how it happens can help answer some of the biggest questions astronomers about how stars survive and die.

“What happened that caused the supernova to explode? How did the black hole approach the collision? What made the beautiful and symmetrical objects we call planetary nebulae? Astronomers have suspected for years that the common envelope is similar to these problems. Part of the answer. Now we have a new way to study this important but mysterious stage,” he said.

Understanding the public envelope phase will also help scientists study what will happen in the very distant future, when the sun will also become a larger, colder star-the red giant-and swallow the innermost planet.

“Our research will help us understand how this might happen, but it gave me another more promising perspective.” Daniel Tafoya said: “When these stars’embrace’, they send dust and gas into space, These dust and gas can become components of future generations of stars and planets, and subsequently become the potential for new life.”

The team plans to continue monitoring these 15 stars with ALMA and other radio telescopes. Through the future telescope of the SKA Observatory, they hope to study how these stars form their jets and change their surroundings. They also hope to find more clues.

“In fact, we think that the known’water fountains’ may be almost all of the same kind of systems in our entire galaxy. If this is true, then these stars are really the strangest that two stars may experience in living together. , The key to the most beautiful and important process,” Theo Khouri concluded.