While scouring our corner of the galaxy for planets similar to Earth, some scientists have gotten pretty picky. Along with being able to support life, they believe the ideal habitable exoplanet should reside in a solar system that mirrors ours.
But our solar system appears to be unlikely to be easily found elsewhere. Now, astronomers may have done it, according to a new study on the search for “solar system 2.0.”
Our potential match lies about 200 light-years from Earth near a star called HIP 11915 that is very much like our sun. The star can be seen using binoculars near the constellation Cetus in North America’s southern night skies.
Picky, picky, picky
So, what picky set of variables makes this new solar system a special match to our own?
There is strong evidence that it has a planet that mimics our Jupiter, a gaseous giant with a similarly huge mass. Astronomers believe the Jupiter twin also orbits HIP 11915 about the same distance as Jupiter does our sun.
It takes 3,600 days for the twin to circle HIP 11915, similar to Jupiter’s orbital phase around the sun, which takes about 4,330 days.
It’s no wonder it’s hard to find such an exact match. There are a few close calls out there, said Richard Hook, a spokesman for the European Southern Observatory, but this discovery is unique.
“This is the most precise match,” he said. “This is the best Jupiter-like object around a sun-like object.”
A Brazilian-led team of astronomers working at the University of Sao Paulo used powerful technology — the observatory’s 3.6-meter telescope, which houses a device noted for finding exoplanets by analyzing light coming from stars they orbit.
Jupiter, gravity bully
Why does the Jupiter twin matter?
Having a Jupiter in the right place is important. In our solar system, the giant gas planet apparently has played a big role in creating and preserving stability on Earth.
During the formation of the planets, scientists believe, our gas giant swept the inner solar system clean, removing objects that may have crowded orbits.
Its gravitational might is second in strength only to that of our sun, and Jupiter exerts it in the right places, helping to keep flying objects such as asteroids in line and not swarming around in broad swaths. They would be very dangerous for a planet hosting life.
Paleontologists say that one single hefty asteroid strike was enough to wipe dinosaurs off the face of the Earth millions of years ago. The “gravitational bully,” as astronomers like to call Jupiter, bends the paths of objects flying near it, and it reels some big ones right into it.
Solar system hopes
Scientists have been finding exoplanets for more than two decades. In the beginning, they thought they’d quickly see them housed in complex solar systems like our own, but they were mistaken, Hook said.
Instead, they found sun-like stars with a planet or two orbiting them, or multiple larger planets huddled in close orbits around their stars.
The discovery of the Jupiter twin around HIP 11915 has ignited an old hope.
“This discovery is, in every respect, an exciting sign that other solar systems may be out there waiting to be discovered,” said Megan Bedell of the University of Chicago, lead author of the study.
Here comes the sun
For an exoplanet to support life, having a star similar to our sun nearby is a good thing. Such stars are plentiful — an easy find, astronomers say.
Scientists look for exoplanets in their orbits. Those are pretty easy to find, too. The Kepler space telescope alone turned up about 4,000 potential candidates.
Finding an exoplanet that could harbor liquid water and be in a “habitable zone” — just the right distance from a sun-like star so as not to overheat or freeze over — is much tougher. But it has been done a few times.
Finding a perfect Jupiter that potentially helped form a solar system similar to ours is exceptionally hard, Hook said.
Signs of an Earth?
What the scientists haven’t been able to see is an Earth-like exoplanet orbiting HIP 11915. To spot one, its orbit would have to pass in front of its sun-like star at the right angle relative to Earth to create a silhouette that astronomers here could detect.
The orbits around HIP 11915 appear to be tilted in a different plane. But it is possible that more exoplanets, rocky ones like Earth, could exist in that sweet spot between the sun-like star and that Jupiter twin.
“There are indications that there probably are, but there is no direct evidence,” Hook said.
Analyzing the light from HIP 11915, the astronomers have found chemical signatures that hint at their existence.
