Astronomers may have witnessed for the first time a sun-like star devouring a planet, casting light on the fate that will befall Earth some four billion years after the dying sun swells and engulfs our world. A new study finds that it may be the case.
By analyzing countless stars at various stages of evolution, astronomers have discovered that as the sun and stars near the end of their lives, they begin to run out of hydrogen near their cores, their primary source of fuel. This causes the core to contract and the outer shell to expand and cool. In this ‘red giant’ stage, these stars swell to 100 to 1,000 times their original diameter, potentially engulfing nearby orbiting planets.
Kishalay De, an astrophysicist at the Massachusetts Institute of Technology and the study’s lead author, said, “I know this must happen on any planet that orbits a shorter distance than Earth, but I’m not sure about this. It was considered very difficult to provide experimental evidence.” he told Space.com.
For decades, scientists have detected stellar evidence just before and after planet-consuming acts. But researchers had never caught Starr in the act before, De explained.
“Honestly, one of the biggest surprises for me was finding it in the first place,” De said in an email. “Planetary entanglements have been a fundamental prediction in our understanding of stars and planets, but their frequency has been highly uncertain, so it’s always exciting to discover potentially rare events for the first time. ”
In a new study, De and his colleagues made the breakthrough after examining a burst of radiation called ZTF SLRN-2020 that occurred in 2020 in the Milky Way’s disk, about 12,000 light-years away, near the constellation Aquila. I was. During the event, the star he became 100 times brighter in a week.
“Work actually started in 2020 when we weren’t looking for this kind of event,” De said. “I was looking for a more general type of explosion called a nova.” A nova is a stellar explosion that occurs when a red giant fuels a fellow white dwarf.
The initial discovery was made by analyzing data collected by the Zwicky Transient Facility, which operates at Caltech’s Palomar Observatory. The Zwicky Transient Facility scans the sky for stars with rapidly changing brightness, which could be events such as novae.
To learn more about ZTF SLRN-2020, De analyzed the spectrum of light from the bright burst. “I was surprised that this source is mainly surrounded by cold gas, unlike novae, which have hot gas around them,” he said.
The cold gas from such bursts often comes from stellar mergers, De explained. When they later looked at data from the same star collected by the Keck Observatory in Hawaii, they also found molecules that can only exist at very low temperatures.
Cold gases can condense and form dust over time. About a year after the initial discovery, De and his colleagues analyzed data from the same star. This time it was collected using the Palomar Observatory’s infrared camera. Infrared data can produce signals of colder matter, as opposed to brighter visible light signals, which often come from novae and other powerful events.
Scientists have discovered that brief bursts of visible light from the star are accompanied by a very bright near-infrared light signal that slowly fades over six months. This confirmed De’s suspicion that “this source actually formed a lot of dust,” he said.
The final piece of the puzzle came out when researchers looked at data collected by NASA’s NEOWISE infrared space telescope. This suggests that the total amount of energy released by the star since the initial explosion was surprisingly small, about 1,000 times smaller than previously observed stellar mergers.
“This means that any merger with this star must be 1,000 times smaller than any star we’ve ever seen,” De said in a statement. “And it’s a happy coincidence that Jupiter’s mass is about 1/1000th the mass of the Sun. That’s when I realized that this was a planet, and it was colliding with its star.”
Based on the nature of the explosion, astronomers estimated that the event released about 33 Earth’s masses of hydrogen and about 0.33 Earth’s mass of dust. This suggests that the protostar was about 0.8 to 1.5 times the mass of the Sun, and the swallowed planet was about 1 to 10 times the mass of Jupiter.
A similar fate is expected for Earth when the Sun becomes a red giant in about 5 billion years.
“If I were sitting on a planet 10,000 light-years away, I would basically see a similar flash from our solar system — because Earth has much less mass than a planet like Jupiter, so compared to this It’s going to be a little more subdued. We believe we’re involved in this event — which puts the significance of this discovery to the human perspective.
There are many questions this discovery raises. “Did the planet survive the plunge, or did it disappear into stellar matter during the plunge?” De said. “Did the planet come into contact with the star’s surface because of the star’s natural expansion, or did something exert very little pressure on the star to get closer? All of these questions have more to do with this. data will become clearer as we get more. Oppose and find out more upcoming events.”
Now that scientists know what a planetary engulfment looks like, “we can look for similar events in the future, especially as infrared surveys become increasingly popular over the next decade,” De said. “You can also go back to this system and see what the star looks like. Was the star polluted by a planet? Did it rotate due to an energetic eruption?” More importantly, the data themselves provide a starting point on which to base a theory that we can experiment with to understand how the planets themselves affect their host stars.”
The scientists detailed their findings online today (May 3) in the journal Nature.
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