A new stellar death model reveals how our sun is going to die and solves a 25-year-old science problem in the process.
Scientists have finally figured out what will happen to our sun when it dies 10 billion years from now. A new model predicting the lifecycle of stars revealed the sun will flare up into a bright planetary nebula, destroying Earth in the process.
This is the same fate that awaits 90 percent of the major stars in the cosmos as they turn from red giants into white dwarfs. And it seems our sun will be right up there with the best of them, ending in a fiery blaze that will be visible for around 10,000 years, notes a new study published yesterday in Nature Astronomy.
At first, the sun will transform into a red giant as it burns up all the last of its hydrogen. This will make it expand to 250 times its current size and most likely wipe out our planet. Then, the sun will collapse into a white dwarf and leave behind a glowing ring of interstellar gas and dust, shows the new model on star death.
Although it was previously believed that our sun’s mass is too low to generate a white dwarf and, subsequently, a visible planetary nebula, the model predicts that this is not the case anymore.
In fact, this new model shows that “the sun is almost exactly the lowest mass star that still produces a visible, though faint, planetary nebula,” notes a news release from the University of Manchester in the U.K., which led the project.
Study co-author Prof. Albert Zijlstra, from the university’s School of Physics and Astronomy, explains that, upon their death, stars eject a massive cloud of dust and gas, known as a stellar envelope, which “can be as much as half the star’s mass.” The ejected envelope reveals the star’s core, which in turn makes the ring of gas and dust shine bright enough for astronomers to spot the planetary nebula.
Since his team’s model confirms that our sun will go down in the same spectacular manner, closing curtain with a luminous planetary nebula, the study finally sets things straight on a matter that’s been bugging astronomers for 25 years — namely, how can old, low mass stars just like our sun still produce bright planetary nebulae.
In theory, ancient stars that are billions of years old should only be able to make faint nebulae, unlike the more massive younger stars that blaze up in dazzling explosions. At least, that’s what the old stellar death models predicted. This was considered to be particularly true especially if their mass was “anything less than about twice the mass of the sun,” says Zijlstra.
However, the new model proves that it’s actually quite easy for old, low mass stars to form bright planetary nebulae. Zijlstra’s team uncovered that, after ejecting their stellar envelopes, these stars heat up three times faster than previously predicted.
“We found that stars with mass less than 1.1 times the mass of the sun produce fainter nebula, and stars more massive than three solar masses brighter nebulae, but for the rest, the predicted brightness is very close to what had been observed,” Zijlstra pointed out.
“Problem solved, after 25 years!” he added.
According to Zijlstra, this new study yielded a “nice result.”
“Not only do we now have a way to measure the presence of stars of ages a few billion years in distant galaxies, which is a range that is remarkably difficult to measure, we even have found out what the sun will do when it dies!”
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