The stars are at the beginning of the envelope phase. The artist's impression shows us a view from very close to a system in which two stars are sharing the same atmosphere. The atmosphere has been provided by the red giant star. The smaller star interacts with its new surroundings in a dramatic fashion, throwing gas from its poles and slowing down a ring of material at its equator. Danielle Futselaar is an art source.
Most stars live with a companion. Sometimes, two come so close that one can affect the other. When a team of astronomy led by the University of Technology, Sweden, used the telescope to study 15 unusual stars, they were surprised to find that they all recently underwent this phase. The discovery promises new insight on the sky's most dramatic phenomena, and on life, death and rebirth among the stars.
A team of scientists led by the University of Technology studied the stars in our galaxy using a giant telescope. All of the stars are double, and all have recently experienced a rare phase that is poorly understood, but is believed to lead to many other astronomy phenomena. Their results are in the journal Nature Astronomy.
The researchers hoped to find clues to their backstories by directing the antennas ofAlma towards each star and measuring light from different molecule close to each star. Nicknamed "water fountains", these stars were known to the astronomer because of their intense light from water.
The Alma telescope is located 5000 m above sea level in Chile and is ideal for looking through the clouds of dust and stars towards the stars.
We were curious about these stars because they seem to be blowing out quantities of dust and gas into space, some in the form of jets with speeds up to 1.8 million kilometers per hour. Theo Khouri, the first author of the new study, says that they thought they could find clues to how the jets were being created.
Stars are losing up to half their mass.
The scientists used the telescope to measure signatures of carbon monoxide in the light from the stars and compared them to signals from different atoms. CO2, carbon monoxide, is a favorite tool for astronomy and is easy to find in space.
We were able to detect faint signals from several different molecule in the gas ejected by these stars thanks to the sensitivity ofAlma. "We saw details that we weren't expecting to see when we looked closely at the data."
The stars were blowing off their outer layers, but the proportions of the different oxygen atoms in the molecule indicated that they were in another respect.
The stars started their lives with the same mass as the Sun. They have ejected up to 50% of their mass in the last few hundred years. Something really dramatic must have happened to them.
The star system W43A is about 7000 light years away from Earth in the constellation Aquila, the Eagle. The double star at its center is too small to be resolved. The stars' interaction has changed their environment. The two jets that were ejected from the stars are seen in two contrasting colors. The clouds are shown in pink. ALMA, D. Tafoya, and others are credited.
A brief but intimate phase.
Why were small stars losing so much mass so quickly? The scientists concluded that the evidence pointed to one explanation. All of them had just been through a phase in which the two stars shared the same atmosphere, and one of them was completely embraced by the other.
The two stars are in a sort of cocoon. The common envelope phase lasts a few hundred years and is brief. "It's over in the blink of an eye," says team member Daniel Tafoya.
Most stars in a system are in a straight line. The stars share the same atmosphere. It can be a life-changing experience for a star, and may even lead to the stars merging completely.
Some of the sky's most spectacular phenomena can be traced back to this sort of intimate episode. Understanding how it happens could help answer some of the biggest questions about stars.
What happens when a supernova explodes? How do black holes get so close to each other? What makes the objects we call planetary nebulae? Astronomers have suspected for a long time that common envelopes are part of the answers to questions like these. He says that there is a new way of studying this phase.
Understanding the common envelope phase will allow scientists to study what will happen in the future when the Sun becomes a bigger, cooler star.
It will help us understand how that might happen, but it will also give me a more hopeful perspective. The potential for new life can be found in the dust and gas sent out into space by the stars when they embrace.
The team plan to keep an eye on the stars with other telescopes since they seem to be evolving. They hope to study how the stars form their jets with the future telescopes of the SKA Observatory. If there are any, they hope to find more.
The known water fountains could be the only systems of their kind in the whole of our universe. If that's true, these stars are the key to understanding the strangest, most wonderful and most important process that two stars can experience in their lives together.
Theo Khouri, Observational identification of a sample of recent common-envelope events, Nature Astronomy. There is a DOI titled: 10.1038/s41550-021-01528-4.
Nature Astronomy journal has information.
The news about secret embraces of stars was retrieved from thephys.org on December 16, 2011.
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