There aren’t many better ways to spend a weeknight than at a bar knocking back a few beers and answering obscure questions. Who doesn’t like to exercise their imagined mental superiority over the masses?
One night a little more than a year ago, a question came up that I absolutely knew the answer to (as did everyone else in the bar). What is the closest star to the planet Earth other than our own sun? Being the space geek and Star Trek nerd that I am, I immediately threw down the answer of Alpha Centauri, put the maximum number of points down that I could, and confidently turned in my answer.
Naturally, I was wrong.
The closest star to our solar system is actually a red dwarf by the name of Proxima Centauri. Oh sure, it’s gravitationally associated with the Alpha Centauri system, which by the way, is actually a binary star system with two separate giant flaming gas balls circling each other. But you’d never be able to tell them apart – or see Proxima, for that matter – without a pretty decent telescope.
Perhaps that is why Alpha Centauri was discovered in 1839 and Proxima Centauri wasn’t seen until 1915. While Alpha Centauri is the third brightest star seen from our planet (which makes me wonder how it could have been discovered in 1839 when even the Neanderthals could look up and see it), Proxima has a mass about 1/8 the sun and has a very low energy output, making it fairly dim as far as stars are concerned. And seeing as how it’s only about the same distance from Alpha Centauri as Neptune is from our own star, I still feel I got a little bit hosed on that answer. In 50 years, when I’m presented with the same question at a bar trivia night, I’ll be sure to know the correct star.
Or will I?
Technology is advancing all the time, and that includes our ability to survey the night sky. We might think we have a good handle on where all of the objects are that are relatively close to our solar system, but then we have discoveries such as this one that puts all of those assumptions in question.
Researchers at Penn State University recently discovered a brand new star that is the third closest known to our solar system. How has it escaped detection this long? Because it’s a brown dwarf. These underachievers are anywhere between 13 and 80 times the size of Jupiter, which is large enough to not be considered a planet but too small to achieve nuclear ignition. That’s right – they’re just giant balls of gas hanging around in space, wishing they could ignite. I’ll let you make up your own joke here.
The discovery was made using the wide-field infrared survey explorer, or WISE for short. The project launched in December of 2009 with the mission of taking images of the entire sky from space. It takes snapshots every 11 seconds and eventually will image every square inch of space at least eight times. And actually, some regions near the poles will be imaged more than 1,000 times.
The goal of the mission is to cast a wide net to catch all sorts of cosmic treasures that are too dim to notice by other means. This includes cool stars, distant galaxies, asteroids, comets, and a whole lot more. Speaking of asteroids, one of its primary objectives is to figure out just how many asteroids are floating around so that we can calculate the odds of being struck by a meteor.
It’s surprisingly not that low.
As Neil deGrasse Tyson famously said, “If humans one day become extinct from a catastrophic collision, we would be the laughing stock of aliens in the galaxy, for having a large brain and a space program, yet we met the same fate as the pea-brained, space program-less dinosaurs that came before us.”
But I digress.
With millions of images, WISE will give us the opportunity to spot hundreds of millions of objects. And it seems to be doing its job just fine at the moment.
Kevin Luhman, an associate professor of astronomy and astrophysics at Penn State, was looking through some of the images taken by WISE when he noticed an object rapidly moving across the sky in images snapped during a 13-month period. The speed at which it was moving indicated that it had to be fairly close to our solar system. He used the images to calculate its trajectory and figure out where the same object should have been during previous sky imaging programs.
Sure enough, when he checked the spots from programs like the Digitized Sky Survey and the Two Micron All-Sky Survey, the object was right where he thought it should be in a whole bunch of pictures taken between 1978 and 1999. Next, he calculated its redshift to determine how far away from Earth it is.
Redshift is created by the Doppler Effect. You hear it all the time when you’re standing by a road. As a car comes towards you, its speed causes the sound waves it produces to be closer and closer together, making the noise sound higher in frequency. Then as it moves away from you, the opposite effect happens, causing the sound waves to become further apart and the noise to sound lower in pitch.
The same thing happens in light emitted from moving objects. If it’s moving towards us, the light appears slightly bluer. If moving away, it becomes slightly redder. By looking at these subtle shifts in color created during different points in Earth’s orbit, researchers can determine how far away an object is.
And this one turned out to be close. Just 6.5 light years away, to be exact.
Intrigued by how near it was, Luhman then turned to the Gemini South telescope on Cerro Pachon in Chile to obtain its spectrum. This revealed its temperature and the fact that it was a brown dwarf. But it also held another surprise. The star was not one, but two objects, orbiting each other in a binary system.
“It was a lot of detective work,” Luhman said. “There are billions of infrared points of light across the sky, and the mystery is which one — if any of them — could be a star that is very close to our solar system.”
The discovery comes just a few months prior to the recent announcement that NASA’s Kepler space telescope – charged with discovering planets orbiting other stars – has malfunctioned. One of the gyroscopes that keeps the camera pointed in the desired direction has quit doing its job. There is still hope that some work-around can be achieved and that the project can continue, but it doesn’t look all that good.
Let’s hope for the sake of finding cool shit in space that the geniuses in NASA can figure out a way to keep the project trucking along.