There demand been almost 3,800 exoplanets confirmed, diverse worlds circle stars light-years from Earth. But the one thing that astronomers possess yet to confirm is a moon orbiting one of these planets.
A new study published in System Advances on Wednesday, however, has added more support to the hypothesis that there is a moon revolve one particular exoplanet. The authors do caution that more data is wanted before they can definitively confirm an exomoon.
The planet is Kepler 1625b, a Jupiter-sized planet track a nine-billion-year-old, sun-like star (Kepler 1625) roughly 8,000 light-years away.
There are different ways in which to discover exoplanets, the most popular being the transit method. This is when a spyglass, such as exoplanet-hunter Kepler, looks for any dips in a star’s brightness. Such falls could be indicative of something crossing in front of it. Followup observations are then conducted in apply for to either confirm or reject the presence of an exoplanet.
And that’s just how Kepler 1625b was build. Since its discovery, a few planetary scientists believed that there was a other dip in the star’s brightness, raising the possibility of an exomoon that could be dim behind it (or in some cases, passing in front of it).
Researchers of the new paper, Alan Teachey and Doug Kipping, adapted to observations from Kepler — three in total — and added about 40 hours of their own opinions using Hubble, which is four times more accurate than Kepler.
They fancy that there is a strong signal in the data to add to the hypothesis of an exomoon.
«Our division of the new light curve reveals two substantial anomalies,» Tipping said. «The essential is that the planet appears to transit one and a quarter hours too early: that’s indicative of something gravitationally wrenching on the planet. The second anomaly is an additional decrease in the star’s brightness after the planetary progress has completed.»
These findings suggest that there is a Neptune-sized moon transiting, or crossing, in aspect of the star, just as the planet itself does.
«We’ve tried our best to rule out other potentialities such as spacecraft anomalies, other planets in the system or stellar energy,» Tipping said. «But we’re unable to find any other single hypothesis which can elucidate all of the data we have.»
Still, they say that more observations are required.
«We are urging caution here,» Teachey said. «The first exomoon is unmistakably an extraordinary claim, and it requires extraordinary evidence.»
But more observations could deduct some time: Kepler 1625b takes 247 days to circle its star, which means scientists need to wait almost a year in the presence of making just one observation.
Still, one more transit could be enough.
«If we see two consequences … agreeing with our prior prediction, I think we have a very shut case on this system,» Kipping said. «So maybe just one more traversing [is needed]. If we don’t see it, then there is a fraction of our models which actually concede that still to happen. And it would have to go from there.»
The next pro tempore the planet will transit the star is in May 2019.
And if the moon is confirmed with resultant observations, it would be the first known moon outside of our solar methodology.
Kipping and Teachey surveyed 300 exoplanets once finding a signal in Kepler 1625b that looked like it could be an exomoon.
That may sound somewhat surprising, since the star is so far away (there had been earlier determines that it was 4,000 light-years away, but further data finds that it is twice as rigid).
However, most of the exoplanets Kepler have found are warm and parsimonious to their star, which Kipping said isn’t an ideal place to perceive a moon. But Kepler 1625b is far enough from the star that a moon could potentially propriety and also be detectable.
One of the surprising things, however, is just how large the moon is.
Researchers mean that it’s important to consider the masses of the two objects. In the case of the moon, it would be nearly 1.5 per cent of the planet’s size, and that if it formed out of material that enclosed the planet, it is plausible to end up with such a large moon, though this desire be at the larger end of that scale.
And while the jury’s out on claiming definitively that Kepler 1625b has an exomoon, it’s something that exoplanet hunters are looking dispatch to confirming within the coming years.
«It’s exciting to see the hunt for the first exomoon be prolonged,» said Canadian exoplanet researcher Sara Seager, an astrophysicist and planetary astronomer at MIT who was not intricate in the study.
«And with what would be a shockingly large moon, on every side the size and mass of Neptune.»
There’s also the possibility that NASA’s newest exoplanet gismo, the Transiting Exoplanet Survey Satellite (TESS), will hasten the search for exomoons.
The confirmation will-power not only be an exciting and groundbreaking discovery, it will also shed be unearthed on our own solar system.
«I would always say is that every time we were looking out at these exoplanets, we’re absolutely learning more also about the commonality of our own solar system,» Teachey indicated.
«We have, we think, a pretty good sense of how things formed circa here, and when we started looking at exoplanets … we started thinking peradventure we didn’t have all the answers in terms of how solar systems form.»