Far out cosmology: coming death of the sun (Introduction)

by David Turell , Saturday, November 12, 2022, 15:41 (743 days ago) @ David Turell

Complete theory puts it at ten billion years:

https://www.sciencealert.com/scientists-figured-out-when-and-how-our-sun-will-die-and-i...

"How will our Sun look after it dies? Scientists have made predictions about what the final days of our Solar System will look like, and when it will happen. And we humans won't be around to see the Sun's curtain call.

"Previously, astronomers thought the Sun would turn into a planetary nebula – a luminous bubble of gas and cosmic dust – until evidence suggested it would have to be a smidge more massive.

"An international team of astronomers flipped it again in 2018 and found that a planetary nebula is indeed the most likely solar corpse.

"The Sun is about 4.6 billion years old – gauged on the age of other objects in the Solar System that formed around the same time. Based on observations of other stars, astronomers predict it will reach the end of its life in about another 10 billion years.

"There are other things that will happen along the way, of course. In about 5 billion years, the Sun is due to turn into a red giant. The core of the star will shrink, but its outer layers will expand out to the orbit of Mars, engulfing our planet in the process. If it's even still there.

"One thing is certain: By that time, we won't be around. In fact, humanity only has about 1 billion years left unless we find a way off this rock. That's because the Sun is increasing in brightness by about 10 percent every billion years.

That doesn't sound like much, but that increase in brightness will end life on Earth. Our oceans will evaporate, and the surface will become too hot for water to form. We'll be about as kaput as you can get.

"There are other things that will happen along the way, of course. In about 5 billion years, the Sun is due to turn into a red giant. The core of the star will shrink, but its outer layers will expand out to the orbit of Mars, engulfing our planet in the process. If it's even still there.

"One thing is certain: By that time, we won't be around. In fact, humanity only has about 1 billion years left unless we find a way off this rock. That's because the Sun is increasing in brightness by about 10 percent every billion years.

"That doesn't sound like much, but that increase in brightness will end life on Earth. Our oceans will evaporate, and the surface will become too hot for water to form. We'll be about as kaput as you can get.

"There are other things that will happen along the way, of course. In about 5 billion years, the Sun is due to turn into a red giant. The core of the star will shrink, but its outer layers will expand out to the orbit of Mars, engulfing our planet in the process. If it's even still there.

***

"The data model that the team created actually predicts the life cycle of different kinds of stars, to figure out the brightness of the planetary nebula associated with different star masses.

"Planetary nebulae are relatively common throughout the observable Universe, with famous ones including the Helix Nebula, the Cat's Eye Nebula, the Ring Nebula, and the Bubble Nebula.

***

"Almost 30 years ago, astronomers noticed something peculiar: The brightest planetary nebulae in other galaxies all have about the same level of brightness. This means that, theoretically at least, by looking at the planetary nebulae in other galaxies, astronomers can calculate how far away they are.

***

"'The data said you could get bright planetary nebulae from low mass stars like the Sun, the models said that was not possible, anything less than about twice the mass of the Sun would give a planetary nebula too faint to see."

"The 2018 models have solved this problem by showing that the Sun is about the lower limit of mass for a star that can produce a visible nebula.

***

"'This is a nice result," Zijlstra said. "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!'"

Comment we won't be here to see it. This fits Adler's thought that God really caring about us is only a 50/50 chance.