Most stars in the universe live with a companion. There are times, where the two stars come to a close that they engulf each other-with waves of consequences. A team of researchers led by astronomers from the Chalmers University of Technology in Sweden used the Alma telescope to study 15 unusual stars; they were shocked at their findings were all stars recently underwent a unique phase. The discovery showcases new insights into the most dramatic phenomena in the stars.
Discovering Clues on Gas Jets Emitted from Stars
Using the humongous telescope ALMA in Chile, the team analyzed 15 unusual stars in the Milky Way, with the closest roughly 5,000 lightyears from Earth. The team's measurements show that all stars are double, and all have experienced a rare phase recently that is still poorly understood. However, it is believed to lead to numerous astronomical phenomena.
In a study published in the journal Nature Astronomy, titled "Observational identification of a sample of likely recent common-envelope events," researchers directed ALMA antennas to each star. They measured the light from various molecules close to the stars. The team hoped to discover clues to the backstories of the stars. Nicknamed "water fountains," the stars are known to astronomers due to their intense light from water molecules produced by unusually dense and fast-moving gases.
Located roughly 5000m above Chile's sea level, the ALMA telescope is sensitive to light with wavelengths of no less than a millimeter, invisible to the naked eye, but perfect for looking through the layers of dust and interstellar clouds in the Milky Way reports ALMAObservatory.
Analyzing Embracing Stars
Theo Khouri, the first author of the study, says that the team was extra curious regarding the stars due to the quantities of blown dust and gases from the stars to space, some forming jests with speeds of up to 1.8 million kilometers per hour. Explaining that the team believed they would find clues as to how the jets were formed, but instead, they found something much more interesting.
According to PhysOrg, scientists used ALMA to measure signatures of carbon monoxide in the light from the stars and compared these signals from various isotopes of oxygen and carbon. Unlike its sister molecule, CO2, carbon monoxide is relatively easier to discover in space and has been a favorite tool of astronomers.
Observations confirmed that the unusual stars were blowing off their outer layers. However, the proportions of the different oxygen atoms indicated that the stars were in another respect not as extreme as astronomers believed, explained Wouter Vlemmings, a member of the team and an astronomer at the Chalmers University of Technology.
The team realized that the reason why small stars were losing so much mass at such a quick pace was that they underwent a unique phase where one star entirely embraced the other. Daniel Tafoya from the Chalmers University of Technology explains that during this rare phase, two stars orbit together in a cocoon. The phenomenon is a brief "common envelope" phase that lasts for only a few hundred years.
Understanding the rare common envelope phase will help scientists understand what will happen in the distant future when the Sun becomes bigger and cooler, engulfing the innermost planets. They were also hopeful that the intimate episode they witnessed would help them answer some other important questions like how stars live and die.
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