Thursday, July 22, 2021


The long relationships between stars and the planets around them - including the Sun and Earth - may be even more complex than previously thought. This is the conclusion of a new study involving thousands of stars using NASA's Chandra X-Ray Observatory.

By conducting the largest X-ray research ever done on regions of star formation in X-rays, a team of researchers helped delineate the link between very powerful eruptions or eruptions of young stars and the impact they could have on orbiting planets.

"Our work tells us how the Sun may have behaved and affected the young Earth billions of years ago," said Kostantin Getman of Pennsylvania State University in University Park, Pennsylvania, who led the study. "In a way, this is our definitive origin story: how the Earth and Solar System came about."

Scientists examined Chandra's X-ray data from more than 24,000 stars in 40 different regions where stars are forming. They captured over a thousand stars that emitted far more energetic flares than the most powerful one ever observed by modern astronomers on the Sun, the "Solar Carrington Event" in 1859. "Super" eruptions are at least a hundred thousand times more energetic than the event Carrington and "mega" flares up to 10 million times more energetic.

These powerful explosions observed by Chandra in this work occur in all regions of star formation and among young stars of all different masses, including those similar to the sun. They are also seen at all different stages of the evolution of young stars, from the early stages, when the star is heavily embedded in dust and gas and surrounded by a large planet-forming disk, to the later stages, when the planets would have if formed and the discs are gone. The stars in the study are estimated to be less than 5 million years old, compared to the Sun's 4.5 billion years old.

The team found that several superflares occur per week for each young star, on average across the entire sample, and about two megaclares each year.

"We want to know what kind of impact - good and bad - these eruptions have on the early life of planets," said co-author Eric Feigelson, also of Penn State. "Flares that powerful can have important implications."

Over the past two decades, scientists have argued that these giant flames can help "give" planets to still-forming stars, driving gas away from the surrounding discs of material. This can trigger the formation of pebbles and other small rock materials that are a crucial step in the formation of planets.

On the other hand, these flames can "take out" planets that have already formed by blasting any atmosphere with powerful radiation, possibly resulting in their complete evaporation and destruction in less than 5 million years.

The researchers also performed detailed modeling of 55 bright super and megaclares and found that most of them resemble the long-lasting flares seen on the Sun that produce "coronal mass ejections," powerful ejections of charged particles that can damage planetary atmospheres. The Solar Carrington event involved such an ejection.

This work is also important to understand the flags themselves. The team found that the properties of flames, such as brightness and frequency, are the same for young stars with and without planet-forming disks. This implies that the flames are likely similar to those seen on the Sun, with magnetic field loops having both footprints on the star's surface, rather than one anchored to the disk and the other to the star.

"We found that these giant flames are like those of the Sun, but they are very amplified in energy and 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 explosions can help us understand the Sun's most powerful eruptions and coronal mass ejections."


The Lagoon Nebula, one of the star-forming regions in the latest study, is about 4,400 light-years from Earth in the Milky Way galaxy, where stars. This field of view shows the southern portion of a large bubble of hydrogen gas, as well as a cluster of young stars. Chandra X-rays (purple) were combined with infrared data (blue, gold and white) were combined with infrared data from the Spitzer Space Telescope in this composite image.

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