{Music throughout] This is KELT-9 b.
It’s about twice the size of Jupiter and it’s always superhot, taking
only 36 hours to orbit its star. It receives
44.000 times more energy than the Sun delivers to Earth.
making it one of the hottest planets known, with a dayside temperature hotter
than the surfaces of some stars. This causes its atmosphere to
boil away into space. Now, thanks to observations
from NASA’s TESS satellite, we know KELT-9 b is even weirder.
TESS spots dips in starlight whenever a planet passes in front
of its star from our perspective. Astronomers call these dips transits.
But KELT-9 b’s odd star complicates things.
It spins so fast it’s squished into an oval. This makes
its poles hotter than its middle, a property scientists call
“gravity darkening.” The planet’s orbit, also odd, carries it over
the star’s poles. Combined, these effects make the start of each
transit different from its end, making further study difficult.
A team led by NASA Goddard scientists used TESS observations
to disentangle these effects and provide further insight into the system.
The polar orbit and gravity darkening give KELT-9 b
an unusual type of season. Summer occurs when it passes
over the star's hot poles. Winter — such as it is —
happens when it passes the cooler equator. And for every 36-hour orbit,
which is KELT-9 b’s year, the planet experiences
these seasons twice ... and each is less than 9 hours long.
Scientists expect the frequently changing temperatures produce wild
winds, and they’re busy modeling KELT-9 b’s atmosphere.
Thanks to TESS, astronomers are equipped to learn more about this
curious system, and others like it.
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