Scientists have found a "warm" planet with twice the mass of Jupiter orbiting a distant dwarf star. The extrasolar planet, or "exoplanet," could be on its way to becoming a so-called "hot Jupiter" by snuggling up to its host star, but only if another planet plays cosmic matchmaker.
With a radius of nearly 1.1 times that of Jupiter and a mass 2.3 times that of the gas giant, this newly discovered exoplanet, designated TOI-4127 b, takes 56.4 days to orbit its host star TOI-4127. The exoplanet's highly eccentric (non-circular) orbit brings it to within around a third of the distance between the Earth and the sun from the star, and its nearly 630 degrees Fahrenheit (332 Celsius) surface temperature means it is classified as a "warm Jupiter."
But, the team thinks this might not be the case for long. Assessing the characteristics of TOI-4127 b the astronomers think it has the capability of becoming a hot Jupiter. But only if another celestial object perturbs its orbit.
TOI-4127 b was discovered by a team of astronomers using NASA's Transiting Exoplanet Survey Satellite (TESS). TESS is in the midst of surveying around 200,000 bright nearby stars with the aim of spotting exoplanets around them.
TESS does this by observing tiny drops in light caused as these planets cross, or "transit," in front of their host star from its vantage point in a 13.7-day, highly elliptical orbit around Earth.
NASA's TESS satellite is adept at spotting planets with short orbital periods that circle their star in 13 days or less. That's because the telescope has an observing period of 27.4 days and a minimum 13-day orbit should let TESS spot a transiting planet at least twice, the minimum number of transits needed to suspect the presence of a planet.
The method has been highly successful with TESS identifying over 6,200 exoplanet candidates since its launch in April 2018. Of these so-called "TESS Objects of Interest, or TOI" around 3,000 have been confirmed.
Many of the exoplanets spotted by TESS thus far are "hot Jupiters," which are defined as worlds of a similar size to Jupiter or larger that orbit their stars extremely closely at distances of around one-tenth of the distance between the Earth and the sun. This results in orbits of around 10 days or less.
Orbiting a dwarf star slightly more massive than the sun and located around 1061 light-years away from Earth, TOI-4127 b, discovered by astronomers led by Pennsylvania State University (PSU) researcher Arvind F. Gupta, is a little different from those hot Jupiters, for now.
Gupta and his co-authors wrote that it's currently thought that warm Jupiters like this exoplanet may spend a fraction of their lives on highly elliptical orbits before shifting to orbits that bring them closer to their stars if they are affected by the gravitational pull of a companion object.
At the moment TOI-4127 b is too widely separated from its star for this interaction to happen between the two, but if it's undergoing a momentum exchange with a currently undiscovered second planet in the system, there is still the chance it may become a hot Jupiter. That means studying this newly discovered exoplanet could be the key to better understanding so-called "hot Jupiter formation pathways."
The team's research is published on the paper repository ArXiv.
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Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.