From University of Michigan, Caltech and UCLA via Science Alert (AU):”Our Solar System Is Going to Totally Disintegrate Sooner Than We Thought”

U Michigan bloc

From University of Michigan

and

Caltech Logo

Caltech

and

UCLA bloc

UCLA

via

ScienceAlert

Science Alert (AU)

29 NOVEMBER 2020
MICHELLE STARR

Milky Way Credits: NASA/JPL-Caltech /ESO R. Hurt. The bar is visible in this image.

1
A white dwarf star after ejecting its mass to form a planetary nebula. Credit: ESO/P. Weilbacher/AIP.

Although the ground beneath our feet feels solid and reassuring (most of the time), nothing in this Universe lasts forever.

One day, our Sun will die, ejecting a large proportion of its mass before its core shrinks down into a white dwarf, gradually leaking heat until it’s nothing more than a cold, dark, dead lump of rock, a thousand trillion years later.

But the rest of the Solar System will be long gone by then. According to new simulations, it will take just 100 billion years for any remaining planets to skedaddle off across the galaxy, leaving the dying Sun far behind.

Astronomers and physicists have been trying to puzzle out the ultimate fate of the Solar System for at least hundreds of years.

“Understanding the long-term dynamical stability of the solar system constitutes one of the oldest pursuits of astrophysics, tracing back to Newton himself, who speculated that mutual interactions between planets would eventually drive the system unstable,” wrote astronomers Jon Zink of the University of California, Los Angeles, Konstantin Batygin of Caltech and Fred Adams of the University of Michigan in The Astronomical Journal.

But that’s a lot trickier than it might seem. The greater the number of bodies that are involved in a dynamical system, interacting with each other, the more complicated that system grows and the harder it is to predict. This is called the N-body problem.

Because of this complexity, it’s impossible to make deterministic predictions of the orbits of Solar System objects past certain timescales. Beyond about five to 10 million years, certainty flies right out the window.

But, if we can figure out what’s going to happen to our Solar System, that will tell us something about how the Universe might evolve, on timescales far longer than its current age of 13.8 billion years.

In 1999, astronomers predicted [Science] that the Solar System would slowly fall apart over a period of at least a billion billion – that’s 10^18, or a quintillion – years. That’s how long it would take, they calculated, for orbital resonances from Jupiter and Saturn to decouple Uranus.

According to Zink’s team, though, this calculation left out some important influences that could disrupt the Solar System sooner.

Firstly, there’s the Sun.

In about 5 billion years, as it dies, the Sun will swell up into a red giant, engulfing Mercury, Venus and Earth. Then it will eject nearly half its mass, blown away into space on stellar winds; the remaining white dwarf will be around just 54 percent of the current solar mass.

This mass loss will loosen the Sun’s gravitational grip on the remaining planets, Mars and the outer gas and ice giants, Jupiter, Saturn, Uranus, and Neptune.

Secondly, as the Solar System orbits the galactic centre, other stars ought to come close enough to perturb the planets’ orbits, around once every 23 million years.

“By accounting for stellar mass loss and the inflation of the outer planet orbits, these encounters will become more influential,” the researchers wrote.

“Given enough time, some of these flybys will come close enough to disassociate – or destabilise – the remaining planets.”

With these additional influences accounted for in their calculations, the team ran 10 N-body simulations for the outer planets (leaving out Mars to save on computation costs, since its influence should be negligible), using the powerful Shared Hoffman2 Cluster.

3
Hoffman2 Cluster. Credit: UCLA.

These simulations were split into two phases: up to the end of the Sun’s mass loss, and the phase that comes after.

Although 10 simulations isn’t a strong statistical sample, the team found that a similar scenario played out each time.

After the Sun completes its evolution into a white dwarf, the outer planets have a larger orbit, but still remain relatively stable. Jupiter and Saturn, however, become captured in a stable 5:2 resonance – for every five times Jupiter orbits the Sun, Saturn orbits twice (that eventual resonance has been proposed many times, not least by Isaac Newton himself).

These expanded orbits, as well as characteristics of the planetary resonance, makes the system more susceptible to perturbations by passing stars.

After 30 billion years, such stellar perturbations jangle those stable orbits into chaotic ones, resulting in rapid planet loss. All but one planet escape their orbits, fleeing off into the galaxy as rogue planets.

That last, lonely planet sticks around for another 50 billion years, but its fate is sealed. Eventually, it, too, is knocked loose by the gravitational influence of passing stars. Ultimately, by 100 billion years after the Sun turns into a white dwarf, the Solar System is no more.

That’s a significantly shorter timeframe than that proposed in 1999. And, the researchers carefully note, it’s contingent on current observations of the local galactic environment, and stellar flyby estimates, both of which may change. So it’s by no means engraved in stone.

Even if estimates of the timeline of the Solar System’s demise do change, however, it’s still many billions of years away. The likelihood of humanity surviving long enough to see it is slim.

Sleep tight!

See the full article here .


five-ways-keep-your-child-safe-school-shootings

Please support STEM education in your local school system

Stem Education Coalition

UC LA Campus

For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

Caltech campus

U MIchigan Campus

The University of Michigan (U-M, UM, UMich, or U of M), frequently referred to simply as Michigan, is a public research university located in Ann Arbor, Michigan, United States. Originally, founded in 1817 in Detroit as the Catholepistemiad, or University of Michigania, 20 years before the Michigan Territory officially became a state, the University of Michigan is the state’s oldest university. The university moved to Ann Arbor in 1837 onto 40 acres (16 ha) of what is now known as Central Campus. Since its establishment in Ann Arbor, the university campus has expanded to include more than 584 major buildings with a combined area of more than 34 million gross square feet (781 acres or 3.16 km²), and has two satellite campuses located in Flint and Dearborn. The University was one of the founding members of the Association of American Universities.

Considered one of the foremost research universities in the United States,[7] the university has very high research activity and its comprehensive graduate program offers doctoral degrees in the humanities, social sciences, and STEM fields (Science, Technology, Engineering and Mathematics) as well as professional degrees in business, medicine, law, pharmacy, nursing, social work and dentistry. Michigan’s body of living alumni (as of 2012) comprises more than 500,000. Besides academic life, Michigan’s athletic teams compete in Division I of the NCAA and are collectively known as the Wolverines. They are members of the Big Ten Conference.