Five years after the active life of the Kepler space telescope ended, scientists have discovered a new solar system that includes at least seven planets in the massive amount of data collected by the telescope.
The planets in question orbit Kepler-385, a Sun-like star that is 10% larger and 5% warmer than our parent star. The two inner planets are slightly larger than Earth and are probably rocky. It is also believed to have a delicate atmosphere. The five exoplanets are about two times larger than our home planet and are likely surrounded by thick atmospheres.
The system is special for several reasons. So far, we know of only a few solar systems with more than six verified planets (see box). What is also striking is that this system consists of planets that are all glowing with heat. Researcher Jack Lessauer said: “Kepler 385 is the first planetary system discovered to host seven hot planets.”
The planet hunter Kepler was operating between 2009 and 2018 and discovered planets using the so-called transit method. Essentially, a space telescope stares at the stars for a long time, hoping to see their brightness fade at regular intervals. Such dips in brightness could indicate the presence of a planet that occasionally passes between its parent star and Kepler, temporarily blocking some of the star’s light. Kepler has discovered thousands of planet candidates this way. These are planets whose existence is considered plausible, but has not yet been proven, based on Kepler’s observations. Follow-up observations (often with other telescopes) are needed to verify its existence and convert the candidate planet into a planet.
Kepler studied Kepler-385 for a long time and found a decrease in brightness indicating the presence of planets. The existence of some of these planets was already confirmed in 2014. But re-analysis of old Kepler data now allows researchers to upgrade the remaining planet candidates around Kepler 385 to planet status. This brings the total number of planets discovered around this star to seven! Researchers can also describe these planets well, for example, saying more about their size, nature (rocky or not) and atmosphere. In addition, we know that planets are very close to their star and are therefore bathed in starlight. The result is clear: the planets are very hot.
“this New search “It shows that a lot of information can still be extracted from the Kepler mission, even though it has already ended,” says researcher Jason Stephen. “By studying these distant planetary systems, we can get a better idea of our history and how it differs from the history of other systems.”
The discovery of seven planets orbiting Kepler 385 is just one of the most notable results of a new study, as scientists reanalyzed data collected by Kepler between 2009 and 2018. The goal was not to use this analysis only to confirm the existence of a number of candidate planets; The researchers also wanted to more accurately characterize the planets discovered by Kepler. “Now that we have some time to analyze the data, we can improve our estimates of some properties of planets in different systems, such as their orbital periods and sizes,” Stephen explains. “This is the definitive catalog of planets discovered during the Kepler mission.” This “catalogue” contains approximately 4,400 planets (candidates). Some of these planets are not alone, but are accompanied by one or more planets as they orbit around their parent star: more than 700 of these multi-planet systems can be found in the new catalogue. “We have compiled the most accurate list of candidate planets and their characteristics ever discovered by Kepler,” Lessauer concludes.
The new catalog was also made possible thanks to other observatories. For example, the researchers used Gaia: a satellite that can pinpoint the distance, positions and movements of stars with extreme precision, and can also monitor changes in the brightness of those stars. Not only does this data provide more information about the stars in question, but it is also relevant to our understanding of any planets orbiting them. For example, researchers can use Gaia data to precisely determine the planet’s orbital period. Analyzing these trading times also leads to a fascinating discovery. That is, planets that are part of a system containing several planets have a more circular orbit than planets that orbit their parent star alone or with a single companion.
Of course, the catalog is not just a finished product; Researchers hope this will be a precursor to more. It is a better understanding of other planetary systems, and thus also a better picture of how unique our system is – with life in it – or not.
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