This artist’s impression shows a hot Jupiter planet orbiting close to one of the stars in the rich old star cluster Messier 67, in the constellation of Cancer (The Crab). Astronomers have found far more planets like this in the cluster than expected. This surprise result was obtained using a number of telescopes and instruments, among them the HARPS spectrograph at ESO’s La Silla Observatory in Chile. The denser environment in a cluster will cause more frequent interactions between planets and nearby stars, which may explain the excess of hot Jupiters.

Paper Spotlight: “A Possible Mechanism for Driving Oscillations in Hot Giant Planets”

In the same way earthquakes can shake the Earth when tectonic plates shift, so too can stars shake, or more scientifically, oscillate, as a result of the motion of hot plasma inside of the star. Similarly, gas giant planets like Jupiter and Saturn can oscillate, too, but astronomers aren’t exactly sure as to why.

Recently, 3rd year graduate student Ethan Dederick and his adviser, Jason Jackiewicz, unveiled a theory behind these planetary oscillations and had a paper entitled “A Possible Mechanism for Driving Oscillations in Hot Giant Planets” accepted for publication by the Astrophysical Journal. Their study examined Hot Jupiters, which are gas giant planets like Jupiter except that they orbit as close as 2 million miles to their host stars (for reference, the Earth is 93 million miles from the Sun). The process they discovered is called the “radiative suppression mechanism.”

The radiative suppression mechanism works by enhancing a minor oscillation, which can be caused by some random event like an asteroid impact or large cloud motions, for example. As the oscillatory wave travels through the atmosphere, the gas will expand and contract periodically. As the planet’s atmospheric layers expand, the gas becomes less dense and more transparent, which will allow more energy to escape from the gas in deeper layers. As the layers contract, they become hotter, denser, and more opaque. These denser layers will try to radiate their extra energy away in order to allow the planet to cool (as planets tend to do). However, since Hot Jupiters are so close to their parent star, the heat from the star will be re-absorbed by the planet’s dense layers, further heating the gas. This excess heat is converted into the necessary energy needed to drive the oscillation process.

Since it is extremely difficult to observe oscillations on extrasolar planets, this process won’t be able to be observationally confirmed or refuted until technology advances a little farther. So for now the research of Ethan Dederick and Jason Jackiewicz remains an interesting theory, one that could potentially help other astronomers in their research.

Take a look at Ethan and Jason’s paper by clicking this link.


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