The Jupiter twin was seen 17,000 light-years away

Two views of the region near where the newly discovered planet was found, the one on the left from Kepler and the one on the right from the Canada-France-Hawaii Telescope (CFHT).

Two views of the region near where the newly discovered planet was found, the one on the left from Kepler and the one on the right from the Canada-France-Hawaii Telescope (CFHT).
Picture: NASA / Kepler / CFHT

An exoplanet with distinct Jupiter-like properties has been discovered in ancient data collected by NASA’s Kepler space telescope. It is noteworthy that Kepler made the observation using gravitational microlensing, in what is the first for a space-based observatory.

The new research is set to be published in the Monthly Notices of the Royal Astronomical Society, and it describes K2-2016-BLG-0005Lb, an extrasolar planet with about the same mass as Jupiter and orbiting in a position comparable to Jupiter’s distance from our sun. Data collected by Kepler in 2016 were the key to the detection. ONE pre-print of the study is available on arXiv.

“This discovery was made using a space telescope that was not designed for microlens observations and in many ways is extremely suboptimal for such a science,” the researchers, led by PhD student David Specht of the University of Manchester, wrote in the newspaper. “Nevertheless, it has provided a direct planetary mass measurement of high precision, mainly thanks to uninterrupted high observation cadence, which is facilitated by observing from space.”

K2-2016-BLG-0005Lb is “the first bound microlensing exoplanet discovered from space-based data,” the researchers say. In fact, Kepler managed to spot over 2,700 confirmed exoplanets during his famous nine-year career (the mission ended in 2018), but this is the first time that Kepleror any space-based telescope for that matter, managed to spot an extrasolar planet through a microlens event.

Predicted by Albert Einstein, gravitational microlensing is a kind of cosmic magnifying glass that allows astronomers to see exaggerated views of celestial bodies that would otherwise be obscured by objects in the foreground, such as stars. Heavy objects cause light to bend over large distances. This allows astronomers to see the light from a background star from our vantage point as the light curves around the object in the foreground.

“Planets only magnify starlight while being almost perfectly in line with a background star,” Eamonn Kerins, a co-author of the study and lead researcher for the Science and Technology Facilities Council, wrote to me in an email. “Approximately only one in 100 million stars in our galaxy has their light visibly distorted by the gravitational field of the planets. And when the distortions happen, they are very short and last from a few hours to maybe a day. “

Kerins said this kind of signal is very difficult to detect, as astronomers have to study the brightness of many millions of stars every few months, sometimes for years. They then have to parse through huge amounts of data in hopes of finding the signals. Kepler, which relied on the transit method to spot exoplanets (where the periodic attenuation of stars is a sign of planets passing in front of them), was not really built for this.

“The biggest problem with Kepler is that its camera has large pixels that give us a sort of Minecraft view of the inner galaxy. All the stars look really blocked, and there are many of them in every pixel, ”Kerins explained. “The key was to model very precisely how Kepler’s pixels react in very crowded star fields. Most stars in the field do not vary, so we can inspect Kepler’s camera behavior with these stars to construct the clearest possible signal from the lens star that varies. “To which he added,” It was hard! “

The astronomers looked at Kepler data from 2016, specifically data from Campaign 9 of the Kepler K2 mission. A new search algorithm marked five candidate microlens signals from the dataset (as revealed in research from 2021), of which the one-spot near galactic bulge – turned out to be a “clear” microlens event according to the new study.

It’s just that five – yes five – ground-based studies scanned the same place in space at the same time, namely the Optical Gravitational Lensing Experiment (OGLE-IV), Canada-France-Hawaii Telescope (CFHT), Microlensing Observations in Astrophysics (MOA) -2), Korean Microlensing Telescope Network (KMTNet) and United Kingdom InfraRed Telescope (UKIRT). The data from these observatories were used to confirm the Kepler data and further characterize the Jupiter-like planet. These campaigns looked in the right place at the right time, but “none of the ground-based surveys marked K2-2016-BLG-0005 in advance” of the 2021 survey, the researchers write.

The newly spotted exoplanet is 17,000 light-years from Earth. It has practically the same mass as Jupiter and a similar orbit in terms of distance to the host star. This planet is “one of the closest cousins ​​to Jupiter, which has so far been found by any method,” Kerins said. “It is also almost twice as far from us as the second longest of the thousands of planets found by Kepler,” he said, adding that “by using this new method, we have been able to expand Kepler’s reach massively. “

Kepler no longer exists, but NASA is on its way Nancy Grace Roman Space telescope, scheduled to be launched later this decade, is specifically being built to find planets using microlensing. Kerins hopes that the Roman telescope will, among other things, reveal the planetary architectures of other star systems and the abundance of potentially habitable worlds in the Milky Way. “It’s going to be a great trip,” he said.

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