Newborn star’s X-rays shine light on Solar System’s early days
In a new study, astronomers report the first detection of X-rays from a Sun-like star in the earliest phase of its evolution. This discovery may help scientists explore the earliest days of our Solar System and rewrite cosmic history.
In 2017 the Chandra X-ray Observatory detected an X-ray flare coming from the very young star HOPS 383, which is the same type of star as our Sun. The star, known as a ‘protostar’ because it’s in the earliest phase of star evolution, lies about 1,400 light years away from Earth and will grow to have about half the mass of our Sun.
In the new research, scientists studying the X-ray flare, which lasted for three hours and 20 minutes, gained insights that change our understanding of when stars like our Sun begin emitting high-energy radiation into space.
“We don’t have a time machine that lets us directly observe our Sun as it was beginning its life, but the next best thing is to look at analogues of it like HOPS 383,” said Nicolas Grosso, of the Astrophysics Laboratory of Marseille at AixMarseille University in France. “From these we can reconstruct important parts of our own Solar System’s past.”
While scientists know that young stars more actively emit X-rays than older stars, it hasn’t been clear exactly when stars begin emitting X-rays. According to Grosso and his team, the new finding “resets the timeline for when astronomers think Sun-like stars start blasting X-rays into space.”
Originally, the researchers didn’t observe X-rays coming from HOPS 383 outside of this flaring period, implying that outside of the flaring period the object was at least ten-times fainter than when the flare was at its maximum. They also found that the flare was 2,000-times more powerful than the brightest X-ray flare that has been observed from our Sun, a much older star.
Additionally, with stars this young there is often – as there is with HOPS 383 – a ‘cocoon’ of gas and dust that surrounds the star and falls inward towards a disc enveloping the central star. As the material falls inward, there is also an ‘outflow’ of material exiting the young system.
Grosso and his team observed so much outflow coming from HOPS 383 that he believes that the X-ray flare coming from this star could actually be powerful enough to strip electrons from atoms near the base of the outflow. It’s thought that this process could be driving, or accelerating, the outflow via magnetic forces.
“If this connection between X-ray flares and outflows is correct, similar flares may have played an important role in forming our life-giving host star, the Sun,” explained Kenji Hamaguchi of the Center for Research and Exploration in Space Science & Technology and NASA’s Goddard Space Flight Center in Greenbelt, Maryland.