After an unprecedented study aimed at finding Earth-like planets outside the solar system, NASA’s Kepler Space Telescope this week opens the search for free-flying planets to find out how common orphan worlds can be.
Planets without host stars are hard to find, but they exist. Scientists believe that these objects were thrown out of their families in the solar system due to gravitational dynamics. They were lured away by tidal forces by alien pedestrians, or perhaps they were even formed without the use of a parent star. It is not yet known whether orphan planets are frequent or not.
In order to find free-flying worlds, astronomers turn to technology known as microlensing, which occurs when the background light of a star is distorted due to the gravitational effect of another invisible body located between the star and the observation telescope.
“For a lensing event that occurs only because of a single object, the most prominent feature of the light curve is the time scale. In general, a shorter time scale potentially points to a lower mass lens object, ”said astronomer Calen Henderson from the NASA jet propulsion laboratory in Pasadena, California. The timeline for a lensing event caused by freely floating planets can last only a few days or even hours, he added.
“If you are monitoring one star, then you have very little chance of capturing a microlensing event. This will happen only once in a particular star every, possibly 300,000 years, ”Henderson told Discovery News.
“It's like fishing. Microlensing is rare. They are unpredictable and what microlensing researchers have been doing for decades is just an attempt to play this game of numbers, ”he said.
Current ground surveys increase the chances of capturing microlensing. By focusing on tens of millions or even hundreds of millions of stars, they are looking for targets that increase brightness for short periods of time.
Although some variations in the brightness of a star are due to star flares or because the star is what is known as a catastrophic variable and occasionally erupts, other changes are caused by invisible bodies in the foreground light of the background star.
“With K2, we will try to find those events that occur due to the lensing system, which is simply free-floating planets,” said Henderson. To achieve this, the K2 team will work with ground-based researchers to try to get two perspectives of the lensing event, which will allow astronomers to calculate the mass that causes the lensing.
“This is the first time when we have to actually measure the masses of these objects and the first opportunity to find out whether the low-mass objects we find are connected (with the help of gravity) to the receiving star or not,” said Henderson.
Scientists believe that they will be able to detect free-floating planets the size of Saturn or even more, using technology.
K2 Orphan Worlds hunt began on Thursday and is scheduled to last until July 1.
