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Data from NASA\u2019s TESS (Transiting Exoplanet Survey Satellite) mission has revealed two new \u201csuper-puff\u201d planets, giant worlds so light that their density is comparable to cotton candy. Scientists calculate that these Jupiter-sized planets\u2014named TOI-791 b and TOI-791 c\u2014are the \u201cpuffiest\u201d worlds ever found.<\/p>\n
The planets orbit a Sun-like star named TOI-791 that is approximately 1,113 light years away from Earth. The TESS mission first detected the planets by watching for repeated dips in TOI-791\u2019s brightness, a telltale sign that a planet is transiting, or passing in front of, a star. Further study revealed two large planets with unusual features.<\/p>\n
TOI-791 b is nearly the same size as Jupiter but contains just 3.0 percent of Jupiter\u2019s mass. TOI-791 c is even larger than Jupiter but contains just 5.9 percent of Jupiter\u2019s mass.<\/p>\n
\u201cThe main reason these planets are interesting to study is that we didn\u2019t expect to see them at all,\u201d said Jon Jenkins, the science lead for the Science Processing Operations Center at NASA\u2019s Ames Research Center in California\u2019s Silicon Valley, which provided the science-ready data from TESS analyzed in this study. \u201cThey represent a puzzle for us to solve about how giant planets like Jupiter and the super-puffs form.\u201d<\/p>\n
The newly found super-puffs also have unusually long orbits, with TOI\u2011791 b taking 139 days and TOI\u2011791 c taking 232 days to circle the host star. Such long-orbit planets are rare to find, needing long durations of telescope observation to capture and confirm their attributes. From its vantage point in high Earth orbit, TESS was able to gather 1,122 days of data on this planetary system over the course of seven years, giving the research team a wealth of data about the planetary system.<\/p>\n
Further analysis found that TOI-791 b and TOI-791 c are locked in an orbital pattern that allows them to tug on each other gravitationally. As they orbit their host star, the planets alternate pulling on each other, affecting the timing of their transits across the host star. Scientists used that variation in orbital timing to calculate the planets\u2019 masses, cementing their status as low density super-puffs. \u00a0<\/p>\n
\u201cOnly a handful of these super-puffy planets are known, and it is even rarer to find two in the same system,\u201d said lead author George Dansfield of Oxford \u00a0University\u2019s Department of Physics in Oxford, England. \u201cTheir extremely low densities make them fascinating targets for understanding how planetary systems form and evolve.\u201d<\/p>\n
With further study, the super-puffs may have more to tell us about planetary evolution.<\/p>\n
\u201cLarge planet formation is believed to drive the evolution of a planetary system, so further study of these Jupiter-size, but far less than Jupiter-mass, planets is of high value,\u201d said Steve Howell, a NASA Ames research scientist who was involved in this study.<\/p>\n
Scientists hope to learn more about the chemical makeup of the planets\u2019 atmospheres, how their spin affects their shape, and how the tilt of their host star compares to their orbits. Deeper investigation could provide new insight into how TOI-791 b and TOI-791 c migrated through the planetary system during their development, whether their orbits were shaped by interactions with other planets, and how low-density super-puff planets form.<\/p>\n
The study, published today in the Monthly Notices of the Royal Astronomical Society<\/em>, was led by the University of Oxford, in collaboration with Universit\u00e9 C\u00f4te d\u2019Azur\/Observatoire de la C\u00f4te d\u2019Azur and the University of Birmingham.<\/p>\n<\/div>\n