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The discovery of exoplanet TOI-2431 b adds to the growing
list of extreme exoplanets. Artist impression of an exoplanet in orbit around
an orange star. (Credit : NASA Ames/SETI Institute/JPL-Caltech) |
Astronomers have found a fascinating new world that
challenges our understanding of planetary systems. Using NASA's Transiting
Exoplanet Survey Satellite (TESS), an international team of researchers has
discovered TOI-2431 b, an Earth sized planet orbiting a nearby star just 117
light years away. What makes this discovery extraordinary isn't just the
planet's size, it’s how incredibly fast it races around its star.
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Image of the Transiting Exoplanet Survey Satellite (Credit :
NASA) |
TOI-2431 b completes a full orbit around its host star in
just 5.4 hours, making it one of the shortest "years" ever recorded
for any known planet. To put this in perspective, while Earth takes 365 days to
orbit the Sun, this distant world experiences more than 1,600 "years"
in the same timeframe. The planet sits extremely close to its star too, only
about 0.0063 AU away, which is roughly 933,000 kilometres.
This proximity comes with extreme consequences. The planet's
surface temperature reaches approximately 2,000 Kelvin (about 1,727°C), hot
enough to melt most rocks and metals. Scientists believe the planet's surface
is likely molten, creating a landscape of liquid rock and metal.
Despite being classified as Earth sized, TOI-2431 b is quite
different from our home planet. With a radius about 1.53 times larger than
Earth and a mass 6.2 times greater, this world is significantly denser than
Earth. Its density of 9.4 grams per cubic centimetre suggests it's made of much
heavier materials, possibly containing a large iron core or other dense metals.
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Newly discovered exoplanet TOI-2431 b is described as an
Earth-sized planet but is far from similar to our home world (Credit :
NASA/Apollo 17 crew) |
The intense gravitational forces from its nearby star have
likely changed the planet's shape. The team estimate that TOI-2431 b is tidally
deformed, with its shortest axis being about 9 percent shorter than its longest
axis, giving it a somewhat flattened appearance rather than a perfect sphere,
like the Earth but somewhat more extreme.
Perhaps most intriguingly, this planet won't be around
forever. The researchers calculated that TOI-2431 b has a tidal decay timescale
of about 31 million years, the shortest known among similar ultra short period
planets. This means the planet is gradually spiralling into its star and will
eventually be consumed, though the planet’s eventual demise won't happen for
many millions of years.
The discovery team, led by Kaya Han TaÅŸ of the University of
Amsterdam, confirmed the planet using multiple observation methods, including
TESS data, ground based telescopes, and specialised spectrographs. Scientists
noted that TOI-2431 b would be an excellent target for the James Webb Space
Telescope to study further, potentially revealing details about its surface
composition and whether it retains any atmosphere despite the extreme
conditions.
This discovery adds to our growing catalog of extreme worlds
and helps scientists understand how planetary systems form and evolve under
different conditions, expanding our knowledge of the incredible diversity of
planets in our Galaxy.