Measuring the Magnetic Field of Exoplanets

Scientists have developed a new way of measuring the magnetic field of exoplanets, allowing astronomers to understand more about these far-away planets and possibly identify those outside our solar system that are habitable, according to new research.

Since the discovery of the first exoplanet outside the Milky Way some 20 years ago, scientists have been able to learn about the moons, atmosphere, climate, and other characteristics of numerous other exoplanets. Now, a team from Lomonosov Moscow State University in Russia have added magnetic field to the list after estimating the value of the magnetic moment of the planet HD 209458b.

Called Osiris, planet HD 209458b is referred to as a hot Jupiter, only it is one third larger and lighter than Jupiter. In the matter of 3.5 days on Earth, it manages to orbit just once around its host star, HD 209458.

Though Osiris is a well-known and well-studied exoplanet, this is the first time that its magnetic field has been accurately measured. The same can be said of any exoplanet, for that matter.

"This method can be used for every planet, including Earth-like planets," researcher Maxim Khodachenko said in a press release.

Magnetic fields are of particular interest to astronomers given that it is a property of both solid and gaseous planets. On Earth, for example, it protects all people, planets and animals from dangerous cosmic rays, as well as helps animals to navigate in space.

During the study, Russian researchers used observations from NASA's Hubble Space Telescope studied the absorption of the star radiation by the atmosphere of the exoplanet. Then, using this information they estimate the shape of the gas cloud surrounding HD 209458b, the size and the configuration of the magnetosphere.

"The planet's magnetosphere was relatively small being only 2.9 planetary radii corresponding to a magnetic moment of only 10 percent of the magnetic moment of Jupiter," explained researcher Kristina Kislyakova.

Though this is just an indirect method of measuring an exoplanet's magnetic field - direct methods are currently impossible, according to the study - the technique is still helpful for better understanding far-away planets outside our solar system. Finding a world with a similar magnetic field to our own could be a good sign of a Earth-like planet.

The results are described in the journal Science.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).