- 3256 - STARS - in our solar system? Every 50,000 years or so, a nomadic star passes near our solar system. Most brush by without incident. But, every once in a while, one comes so close that it gains a prominent place in Earth’s night sky, as well as knocks distant comets loose from their orbits.
----------------------------- 3256 - STARS - in our solar system?
- Wandering stars pass through our solar system surprisingly often. Our Sun, which is our closest star, has had close encounters with other stars in the past, and it’s due for a dangerously close one in the not-so-distant future.
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- The most famous of these stellar interlopers is called “Scholz’s Star“. This small binary star system was discovered in 2013. Its orbital path indicated that, about 70,000 years ago, it passed through the Oort Cloud, the extended sphere of icy bodies that surrounds the fringes of our solar system.
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- Some astronomers even think Scholz’s Star could have sent some of these objects tumbling into the inner solar system when it passed. However, Scholz’s Star is relatively small and rapidly moving, which should have minimized its effect on the solar system.
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- Scientists have been finding that these kinds of encounters happen far more often than once expected. Scholz’s Star wasn’t the first flyby, and it won’t be the last. In fact, we’re on track for a much more dramatic close encounter in the not-too-distant future.
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- Since this star didn’t appear to be moving much side to side, the star was likely moving toward us or away from us at a breathtaking pace. As the astronomers measured the star’s radial velocity to learn how quickly it was moving toward or away from our Sun. The initial results that this thing came within one parsec [3.26 light-years] of the Sun.
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- It passed closer to our Sun than any other known star. Another wandering star passed within one light-year of the Sun roughly 70,000 years ago. At the time, modern humans were just beginning to migrate out of Africa, and Neanderthals were still sharing the planet with us.
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- The European Space Agency satellite called “Gaia“, is built to map the precise locations and movements of over a billion stars, and we now know about other close encounters. In 2018, a team of researchers used Gaia data to plot our Sun’s future meet-ups with other stars.
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- They discovered nearly 700 stars that will pass within 15 light-years of our solar system over just the next 15 million years. However, the vast majority of close encounters have yet to be discovered. But they suspect roughly 20 stars should pass within just a couple light-years of us every million years.
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- Space is big. Statistically, most of those stars would pass the outer edge of our solar system. That means encounters like the one with Scholz’s Star are common, but only a few are close enough to actually dislodge a significant number of comets,
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- A few stars should still come surprisingly close. And if a large, slow-moving star did pass through the edge of the Oort Cloud, it could really shake up the solar system.
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- Many nearby stars will pass close to the Oort Cloud, but only one will move through it. In about 1.35 million years, “Gliese 710” likely will gravitationally perturb millions of comets, sending a sizable number on a potential collision course with Earth.
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- A massive star steamrolling through the outer solar system is exactly what Gaia data show will happen less than 1.4 million years from now, according to a 2016 study.
The star called Gliese 710 will pass within 10,000 astronomical units.
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- 1 AU is equal to the average Earth-Sun distance of 93 million miles. 10,000 AU is well within the outer edge of the Oort Cloud.
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- At half the mass of the Sun, Gliese 710 is much larger than Scholz’s Star, which is just 15 percent the mass of the Sun. This means Gliese 710’s hulking gravity could potentially wreak havoc on the orbits of icy bodies in the Oort Cloud.
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- While Scholz’s Star was so tiny it would have been barely visible in the night sky, Gliese 710 is larger than our current closest neighbor, Proxima Centauri. So when Gliese 710 reaches its closest point to Earth, it will burn as a brilliant orange orb that will outshine every other star in our night sky.
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- This event could be “the strongest disrupting encounter in the future and history of the solar system. Fortunately, the inner solar system is a relatively tiny target, and even if Gliese 710 does send comets flying our way, it would take millions of additional years for these icy bodies to reach us. That should give any surviving future humans plenty of time to take action. Yeah right, if we could just stop fighting each other!
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- And in the meantime, they can enjoy watching what may be one of the closest stellar flybys in the history of our solar system.
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- How do we discover these wandering comets? Sometimes the old methods are the best methods. When astronomer Clyde Tombaugh discovered Pluto in 1930, it was the result of countless hours spent straining his eyes at a machine called a “blink comparator“. Using it, Tombaugh could flip rapidly back and forth between two images of the night sky taken at slightly different times.
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- Volunteers comb through images of our celestial neighborhood, looking for new worlds near to us, just like Tombaugh. But instead of planets, they’re now looking for something even stranger. The search today is focused on a strange class of objects known as “brown dwarfs“, Sized to be not quite planets, not quite stars.
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- Scientists involved with the project have now released the most up-to-date map yet of brown dwarfs stars near Earth, something they say wouldn’t have been possible without the hard work of citizen scientists.
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- The map will help astronomers better understand how brown dwarfs form and evolve, and give researchers a better idea of the objects that populate the space just beyond our own solar system. Their research was published online in late 2020.
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- February 18, 1930, Tombaugh was flipping through recent images when he noticed a tiny dot that jumped back and forth, a sign that he’d found a nearby object. Further observational work ruled out other objects like asteroids, and the discovery of the onetime ninth planet was official. Today, Pluto has been demoted to the status of dwarf planet as we’ve discovered other objects like it in the Solar System.
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- Astronomers have strong suspicions that we’re not yet done discovering worlds in the outer reaches of the Solar System quite yet. A number of minor planets and other so-called “Kuiper Belt objects” have been discovered in recent years. And some astronomers think there’s another large planet orbiting far out beyond Neptune, which they call “Planet Nine.”
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- Even further out in our celestial neighborhood there are likely to be a number of dim, mysterious objects known as brown dwarfs. Too large to be planets but not large enough to be stars, brown dwarfs are a strange kind of in-between object. They’re typically defined as being somewhere between 13 and 80 times the mass of Jupiter.
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- The updated map includes 525 brown dwarfs within 65 light-years of Earth, but more are surely waiting out there. Brown dwarfs are very hard to find. Because they aren’t big enough to begin fusing hydrogen into helium, the process that powers our Sun and other stars, brown dwarfs are often quite cool, meaning they don’t emit a lot of radiation that astronomers can pick up on.
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- Astronomers have found a wide variety of brown dwarfs that differ in terms of composition and internal activity. Still, many questions remain about how brown dwarfs form and what they look like. More observations are needed to get to the bottom of the mystery.
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- That’s where citizen science comes in. Astronomers already have access to broad, high-resolution photos of nearly the entire night sky from data gathered from NASA’s Wide-field Infrared Survey Explorer, or WISE, spacecraft. Beginning in 2009, the satellite scanned the heavens in various infrared frequencies, and a second phase, dubbed NEOWISE, began in 2013.
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- Astronomers planned to follow up on anything interesting they spotted in the WISE images with other, more powerful infrared telescopes like the Spitzer Space Telescope. But they soon ran into a big problem: NASA was planning on shutting Spitzer down. To find anything, the scientists would need to move quickly.
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- Volunteers use an online tool to quickly flip through images of the night sky taken a short time apart. If they spot something moving, they’re able to alert astronomers, who’ll follow up on their work with more powerful observations using observatories.
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- Volunteers found dozens of new brown dwarfs candidates that scientists were able to follow up on with Spitzer to help create the new map. In all, the citizen scientists helped add 52 new brown dwarfs in just a year.
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- Though Spitzer shut down in January of 2020, the astronomers were able to follow up on many promising candidates citizen scientists picked out. This led to the discovery of, among other things, a new class of brown dwarf, called extreme “T-type sub dwarfs“.
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- These objects are extremely old, in some cases around 10 billion years old, scientists. Other unique observations from the new map include the coldest known brown dwarf, a place where temperatures probably dip below the freezing point.
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- One of the citizen scientists did find a really, really faint object that was just streaking across the sky. And we thought, ‘What is this? This is going to be something weird. The object didn’t match the spectrums of anything they had on file. Further findings showed it was a very ancient cold brown dwarf composed largely of hydrogen, without the metals most other brown dwarfs have.
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- One volunteer even coded a tool, known as WiseView, that makes the process of discovering brown dwarfs far easier by allowing participants to flip easily back forth through the images.
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-Volunteers are invited to listen in on weekly telephone meetings between the scientists as well, where they discuss recent results and new objects to focus on.
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- To join in with citizen scientists across the world, and to get a little taste of how Clyde Tombaugh found Pluto, head to the Backyard Worlds project affiliate page on SciStarter. In your SciStarter dashboard, add your Zooniverse name under "Info & Settings" to earn credit for your participation. And maybe you’ll even find your own world, floating out there in space.
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- August 22, 2021 STARS - in our solar system? 3256
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