Hot Jupiter WASP-12b is Spiraling In Toward Its Star: Study | Astronomy – Sci-News.com
WASP-12b will be completely consumed by its host star in 3.25 million years, according to a new study led by Princeton University astrophysicists.
An artist’s concept of the hot-Jupiter exoplanet WASP-12b. Image credit: NASA / ESA / G. Bacon, STScI / C. Haswell, Open University.
WASP-12b was discovered by the UK’s Wide Area Search for Planets (WASP) project in April 2008.
The planet orbits WASP-12 (also known as Bergfors-6), a yellow dwarf star located 1,411 light-years away in the constellation of Auriga.
It has a mass 1.4 times that of Jupiter, a radius almost twice that of Jupiter, and an orbital period of just 1.09 day.
WASP-12b is so close to the star that its daylight side is superheated to nearly 2,540 degrees Celsius (4,600 degrees Fahrenheit).
Since the planet’s discovery in 2008, the time interval between transits of WASP-12b in front of its star has been decreasing by 29 ms/year.
“The problem is that as WASP-12b orbits its star, the two bodies exert gravitational pulls on each other, raising ‘tides’ like the ocean tides raised by the moon on Earth,” said study first author Samuel Yee, a graduate student at Princeton University.
“Within the star, these tidal waves cause the star to become slightly distorted and to oscillate.”
“Because of friction, these waves crash and the oscillations die down, a process that gradually converts the planet’s orbital energy into heat within the star.”
“The friction associated with the tides also exerts a gravitational torque on the planet, causing the planet to spiral inward.”
Measuring how quickly the orbit of a planet is shrinking reveals how quickly its host star is dissipating the orbital energy, which provides astrophysicists clues about the interior of stars.
“If we can find more planets like WASP-12b whose orbits are decaying, we’ll be able to learn about the evolution and eventual fate of exoplanetary systems,” Yee said.
“Although this phenomenon has been predicted for close-in giant planets like WASP-12b in the past, this is the first time we have caught this process in action.”
The study was published in the Astrophysical Journal Letters.
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Samuel W. Yee et al. 2020. The Orbit of WASP-12b Is Decaying. ApJL 888, L5; doi: 10.3847/2041-8213/ab5c16
