Magnetic fields significantly affect hot Jupiter atmospheres, research finds

Aug 29, 2013 by Shannon Hall, Universe Today
A video of Jupiter’s atmosphere. While Jupiter is drastically different from hot Jupiters, its atmospheric circulation is proving to be similar. Credit: NASA.

Determining weather patterns in exoplanet atmospheres – hundreds to thousands of light years away – is extremely difficult. However, given that it may be one of our best ways to truly characterize these alien words, it's a challenge astronomers have accepted willingly.

Most models have a very simple foundation, necessarily eliminating the complex physics that is difficult to incorporate and analyze. Recently, a team led by Dr. Konstantin Batygin of Harvard University, added one more parameter to their models, drastically changing their results.

The punch line is this: the inclusion of magnetic fields significantly changes, and actually simplifies, the atmospheric circulation of hot Jupiters.

Hot Jupiters orbit dangerously close to their host stars, roasting in stellar radiation. But they are also tidally locked to their host stars – one hemisphere continually faces the star, while one continuously faces away – creating a permanent dayside and a permanent nightside.

One would expect the between the dayside and the nightside to be very high. However, various play a role in strongly decreasing this temperature gradient. As an example, we now know that clouds may significantly decrease the temperature of the dayside.

Dr. Batygin's team analyzed within . "The case of hot Jupiters is quite peculiar," she told Universe Today. "The atmospheres of hot Jupiters have temperatures that reach up to 2000 Kelvin, which is hot enough to ionize trace Alkali metals such as potassium and sodium. So the air on hot Jupiters is actually a weakly conducting plasma."

Once the have been ionized – stripped of their electrons – the contains all of those charged particles and becomes a plasma. It is then electrically conductive and magnetic effects must be taken into account.

While the underlying physics is pretty complex (with nearly 40 multi-lined equations in the paper alone), the introduction of magnetic effects actually simplified the model's outcome.

In the absence of magnetic fields, the upper and lower atmospheres feature two distinct patterns of circulation. The upper atmosphere consists of winds blowing away from the dayside in all directions. And the lower atmosphere consists of zonal flows – the bands of color on Jupiter. The zonal flows move parallel to lines of latitude in an east-west fashion. Each moves in a different direction than the one above and below it.

"Upon introducing magnetic fields, fancy dayside-to-nightside flows are quenched and the entire atmosphere circulates in an exclusively east-west fashion," explains Dr. Batygin. The upper atmosphere resembles the lower atmosphere – zonal flows dominate.

Throughout these models, Dr. Batygin et al. assumed a aligned with the rotation axis of the planet. Future work will include a closer look at the effect of a more complicated geometry. The team also intends to extend these results to hotter atmospheres, where magnetic fields will slow the rate of these zonal flows. According to Dr. Batygin, "this has potentially observable consequences and we hope to elucidate them in the future."

These results will be published in the astrophysical journal (preprint available here).

Explore further: Astrophysicists offer new research, tool for identifying habitable zones

add to favorites email to friend print save as pdf

Related Stories

Stellar winds may electrify exoplanets

Jun 05, 2013

(Phys.org) —The strangest class of exoplanets found to date might be even stranger than astronomers have thought. A new model suggests that they are partially heated by electric currents linked to their host stars. Florida ...

Star Tau Boo's baffling magnetic flips

Jul 04, 2013

(Phys.org) —The first observations of the complete magnetic cycle of a star other than the Sun are proving a puzzle to astronomers. Tau Boötis, known as Tau Boo (τ Boo), is a yellowish star that is a ...

Big weather on hot Jupiters

May 27, 2013

Among the hundreds of new planets discovered by NASA's Kepler spacecraft are a class of exotic worlds known as "hot Jupiters." Unlike the giant planets of our own solar system, which remain at a safe distance ...

An Exoplanet with a Potassium-Rich Atmosphere

Mar 04, 2011

(PhysOrg.com) -- A hot Jupiter - a type of celestial object unknown only fifteen years ago - is a Jupiter-sized exoplanet orbiting so close to its host star that its atmospheric temperature is thought to be ...

Recommended for you

Image: Multicoloured view of supernova remnant

12 hours ago

Most celestial events unfold over thousands of years or more, making it impossible to follow their evolution on human timescales. Supernovas are notable exceptions, the powerful stellar explosions that make ...

Ultra-luminous X-ray sources in starburst galaxies

12 hours ago

Ultra-luminous X-ray sources (ULXs) are point sources in the sky that are so bright in X-rays that each emits more radiation than a million suns emit at all wavelengths. ULXs are rare. Most galaxies (including ...

When a bright light fades

12 hours ago

Astronomer Charles Telesco is primarily interested in the creation of planets and stars. So, when the University of Florida's giant telescope was pointed at a star undergoing a magnificent and explosive death, ...

Image: Horsehead nebula viewed in infrared

13 hours ago

Sometimes a horse of a different color hardly seems to be a horse at all, as, for example, in this newly released image from NASA's Spitzer Space Telescope. The famous Horsehead nebula makes a ghostly appearance ...

The Milky Way's new neighbour

13 hours ago

The Milky Way, the galaxy we live in, is part of a cluster of more than 50 galaxies that make up the 'Local Group', a collection that includes the famous Andromeda galaxy and many other far smaller objects. ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.