The long-standing interactions between stars and the planets that orbit them, including the Sun and Earth, may be even more complex than previously thought. This is one of the findings of a new study that involved thousands of stars and NASA’s Chandra X-ray Observatory.
A team of researchers has helped outline the link between very powerful flares, or outbursts, from young stars and the impact they could have on planets in orbit by conducting the largest X-ray survey ever of star-forming regions.
“Our work tells us how the Sun may have behaved and affected the young Earth billions of years ago,” said the study’s lead author, Kostantin Getman of Pennsylvania State University in University Park, Pennsylvania. “In some ways, this is our ultimate origin story: the formation of the Earth and Solar System.”
The researchers examined X-ray data from more than 24,000 stars in 40 different regions where stars are forming from Chandra. They captured over a thousand stars that emitted flares that were thousands of times more powerful than the most powerful flare ever observed by modern astronomers on the Sun, the “Solar Carrington Event” in 1859. “Super” flares are at least one hundred thousand times more energetic than the Carrington Event and “mega” flares up to 10 million times more energetic.
The long relationships between stars and the planets around them – including the Sun and the Earth – may be even more complex than previously thought. This is one conclusion of a new study involving thousands of stars using NASA’s Chandra X-ray Observatory.
These powerful flares observed by Chandra in this study occur in all star-forming regions and among young stars of various masses, including those similar to the Sun. They can also be seen at various stages of the evolution of young stars, ranging from early stages when the star is heavily embedded in dust and gas and surrounded by a large planet-forming disk to later stages when planets would have formed and the disks would have vanished. The stars in the study have estimated ages of less than 5 million years, compared to the Sun’s 4.5 billion-year age.
The team discovered several super-flares per week for each young star, on average, and about two mega-flares per year.
“We want to know what kinds of impacts – good and bad – these flares have on the early lives of planets,” said Penn State co-author Eric Feigelson. “Flares of this magnitude can have far-reaching consequences.”
Scientists have argued for the past two decades that these massive flares can help “give” planets to still-forming stars by driving gas away from disks of material that surround them. This can cause the formation of pebbles and other small rocky material, which is a necessary step in the formation of planets.
These flares, on the other hand, may “take away” planets that have already formed by blasting any atmospheres with powerful radiation, potentially resulting in their complete evaporation and destruction in less than 5 million years.
The researchers also performed detailed modeling of 55 bright super- and mega-flares and discovered that the majority of them resemble long-lasting Sun flares that produce “coronal mass ejections,” powerful ejections of charged particles that can damage planetary atmospheres. Such an ejection occurred during the Solar Carrington Event.
This research is also important for understanding flares. The researchers discovered that the brightness and frequency of flares are the same for young stars with and without planet-forming disks. This implies that the flares are likely similar to those seen on the Sun, with magnetic field loops leaving both footprints on the star’s surface, rather than one anchored to the disk and one to the star.
“We discovered that these giant flares are similar to those seen on the Sun, but they are greatly magnified in terms of energy, frequency, and the size of their magnetic loops,” said co-author Gordon Garmire of the Huntingdon Institute for X-ray Astronomy in Huntingdon, Pennsylvania. “Understanding these stellar outbursts may aid in our understanding of the Sun’s most powerful flares and coronal mass ejections.”
