A group of astronomers announced this week they found evidence that points to the existence of a giant exomoon the size of Neptune. The moon is located about 4,000 light-years away, and it orbits a giant planet.
Astronomers believe if the finding is confirmed it would have significant consequences in the study of the cosmos, as the large exomoon would be the first ever to the found orbiting an alien world.
Image credit: NASA / JPL-Caltech / Space Science Institute, CC BY-ND / The Conversation
Alex Teachey and David Kipping from Columbia University found the evidence while hunting for exomoons on the space using the Kepler Space Telescope.
Researchers present evidence for an exomoon candidate 4,000 light-years away
Finding such a large moon at vast distances is not easy, and the team noted they need to collect more evidence before affirming the sighting was, in fact, an exomoon orbiting an alien planet. Their early results were published Wednesday on the preprint service arXiv.
Teachey and Kipping already scheduled the time to use the Hubble Space Telescope in October this year to see if the signal they found still holds up.
“This candidate is intriguing, and we obviously feel good enough about it that we’ve asked for Hubble time,” Teachey told National Geographic via email. “But we want to be crystal clear that we are not claiming a detection at this point.”
Finding such a large moon at vast distances is not easy. Image credit: Petridishorg Youtube Channel
Kipping had been working for years on a project dubbed the Hunt for Exomoons with Kepler. He and Teachey were analyzing the dips in light from exoplanets transiting in front of their stars. Whenever a second, smaller dip appears behind a planet, there’s a possibility a moon lies behind it. Researchers have suggested that exomoons could be the best places in the universe to look for extraterrestrial life.
However, since those signals are faint and usually inconsistent, it’s hard to determine whether there are exomoons there. In their new paper, the researchers presented the first evidence for an exomoon candidate. They had analyzed data from 284 planets that seemed like candidates for hosting exomoons. Kipping told Science News that out of those planets, that object popped out.
Kepler-1625b could be the host of a Neptune-size exomoon
Out of the 284 planets spotted by Kepler, some of them are as big as Jupiter but are close to their stars, said the researchers. Astronomers have theorized these hot Jupiter-like planets developed in the cooler outskirts of their star systems but then moved inward, which has raised questions about what would happen to their moons.
“They’re looking at planets that are much closer to their suns than Jupiter is to our own,” Matthew Kenworthy from the Leiden Observatory, who was not involved in the research, told National Geographic. “So the question is, during this process of migration, do big fat gas giants lose their moons?”
Out of the 284 planets spotted by Kepler, some of them are as big as Jupiter but are close to their stars, said the researchers. Image credit: SpaceRip Youtube Channel
The data picked up by Kepler suggest that most of those planets don’t have their moons nearby. The researchers believe that no more than 108 of the 284 studied planets could have their moons. That data suggest that many Jupiter-like worlds shed their moons if they migrate inward.
However, when the researchers applied moon models to the Jupiter-sized planets, they found a compelling signal from Kepler-1625b, the planet which they believe hosts the exomoon. Also, they found bumps in the data that led them to believe a Neptune-size body was orbiting Kepler-1625b.
Hubble observations in October will determine whether the finding is correct
National Geographic reports that there’s a 1-in-24,000 chance those bumps in the data are a fluke. While the data may be compelling, it is necessary that the researchers conduct more observations to see whether Kepler-1625b hosts a Neptune-size moon. The Hubble observations in October will determine whether they are right or wrong.
Teachey said that if he were a gambling man, he would bet a bottle of wine –but not his car- on the exomoon’s existence. Kenworthy noted that if the finding is correct, it’d be “awesome.” However, he warned –along with the researchers- the evidence is tantalizing, and it’s not a detection.
“Any time the word ‘candidate’ is in the [study] title, it is just that, a candidate,” MIT planetary scientist Sara Seager, told National Geographic in an email. “I am definitely looking forward to the Hubble Space Telescope observations in 2017 to see if anything is actually there.”
If the moon is confirmed, it would be almost in a class of its own, said the researchers. They calculated that statistically speaking, about 38 percent of Jupiter-sized planets close to their stars are likely to host moons like Jupiter’s. Meanwhile, the researchers will keep waiting for the Hubble observations, when they’ll be able to retrieve more data.
