The field of extrasolar planet studies has advanced over the past three decades. 4,903 extrasolar planets have been confirmed and another 8,414 are waiting to be confirmed. There are many questions about the nature of planet formation and evolution because of the diverse nature of these planets. The role and commonality of natural satellites is an important question.
It is reasonable to assume that moons are ubiquitous in our universe. There are no confirmed exomoons available for study despite thousands of know exoplanets. Thanks to Professor David Kipping and the international team of astronomer, that may have changed. In a recent NASA-supported study, a group of people report on a possible discovery of an exomoon.
The research team included members from NASA, Caltech, the NASA Ames Research Center, the Kavli Institute for Astrophysics and Space Research at MIT, and the Institute for Particle Physics and Astrophysics at UCLA. The paper describing their research was published in the journal Nature Astronomy.
An artist has created an illustration of NASA. Credit: NASA
Professor Kipping is well-known for his work in exoplanet studies. The leader of the Cool Worlds Laboratory at Columbia University has spent years developing methods for the study and characterization of exoplanets. The Harvard-Smithsonian Center of Astrophysics is affiliated with the Hunt for Exomoons with Kepler campaign, which is dedicated to finding evidence of exomoons in the data from the Kepler mission. As Kipping told Universe Today via email.
Those who want to understand how the universe works and those who want to know if we are alone are two different types ofAstronomers. Exomoons hold promise in both themes. They will show how moons manifest in the Universe beyond our shore. When we look at the Moon, we wonder if it was formed through a giant impact, or if it was the result of planet formation.
It's common in sci-fi to have moons as frequent abodes for life. NASA's overarching goal is to understand how common Earth-like worlds are, and looking for moons is a necessary part of that.
The evolution of the Moon is closely related to the evolution of Earth. According to the Giant Impact Hypothesis, both formed after a Mars-sized object collided with a primordial Earth 4.5 billion years ago. Some scientists think that the impact may have been the reason why Earth is now warm. One theory says that the Moon protects us from radiation by keeping the Earth's interior strong.
The study of exoplanet systems and creation of means for detecting exomoons have been done by Kipping and his colleagues. The Transit Timing Variations (TTV) is one of the methods that Kipping and his colleagues have devised to look for them. The transits of exomoons themselves are in keeping with transit photometry. The method of transit.
The strongest exomoon candidate to date was identified by the HEK campaign. The team found evidence of a double planet around a Sun-like star 8,000 light-years away. They presented new evidence from the Hubble Space Telescope that reinforced their previous findings. The only candidate exomoon that is difficult to detect is Kepler-1625b-i. Said Kipping.
Exomoons are difficult to detect because they are expected to be smaller than your typical planet, and further their signals get mixed up with the planetary transit making it hard to disentangle. There are many ways to look for exomoons. We believe that transits are the most effective approach for planet discovery because they are highly successful and offer repeatable events that enable a false hypothesis to be constructed.
Natural satellites are very common around gas/ice giants in the Solar System, all of which can be seen beyond the Frost Line. Cool gas/ice giant exoplanets are logical. The data from the Kepler telescope was used by HEK to look for signs of exomoons making transits along with their parent planets.
An artist's conception of an animal. Credit: NASA.
It's thought that hot-Jupiters are unlikely since they are thought to migrate inwards which would be bad for moon survival. We punted that cool giants were the best place to look. The motivation was due to the abundance of moons on the outer giant planets and the decreased Hill sphere sizes on close-in planets.
The team examined the archival data obtained by Kepler for transits by cool gas giants about two times the size of Jupiter. 73 exoplanets were found after eliminating any object with less than two transits. They looked at the sample based on a planet+moon model to see where the signal was strongest. The strongest candidate was Kepler 1708b.
It was the only thing that passed all the tests. The best way to describe it is that it is a transit signal for which the best fitting astrophysical model is a planet+moon model.
This research is still in its infancy, and it's necessary for time to develop their methods and refine their techniques. We can build upon these successes to eventually find even smaller moons for which we will likely have less irritation with their nature as they converge upon the moons we find in our Solar System, says Kipping.
An artist's impression of a view from a hypothetical moon around an exoplanet. Credit: NASA.
Next- generation telescopes like the James Webb and Nancy Grace Roman will benefit exoplanet and exomoon research greatly in the near future. Astronomers think that the James Webb will take its first images in six months. The search for exomoons will be narrowed by ground-based telescopes like the ELT.
Direct image studies of exoplanets will be carried out using the advanced suites of giant primary mirrors, spectrometers, coronographs, and adaptive optics. Smaller rocky planets that are closer to their stars are expected to be found. The light signatures caused by exomoons may be spotted by these advanced capabilities.
Further reading about nature astronomy.
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