A gas giant labeled HD 189733b is suffering from some severe weather conditions. Winds on the far away exoplanet reach up 5,400 miles per hour. These winds far exceed anything seen on Earth, or in our solar system for that matter. Perhaps the most important part of the discovery, however, is the simple fact that researchers made it at all.
Discovering the details of happenings outside of our own solar system is difficult. While scientists can gather data on light, gravitational pull, and other aspects of faraway objects, discovering details such as wind speed marks a major break though.
Tom Louden, a researcher from the University of Warwick’s, put it this way:
“Whilst we have previously known of wind on exoplanets, we have never before been able to directly measure and map a weather system.”
The planet under observation, HD 189733b, is a gas giant, somewhat akin to Jupiter, Neptune, and the other gas giants found in our solar system. It resides in the Vulpecula Constellation, which is located some 63 light years from Earth.
According to Mr. Louden, “HD 189733b’s velocity was measured using high resolution spectroscopy of the Sodium absorption featured in its atmosphere. As parts of HD 189733b’s atmosphere move towards or away from the Earth the Doppler effect changes the wavelength of this feature, which allows the velocity to be measured”.
Thus, Scientists were able to measure the winds by using a combination of spectroscopy and the Doppler Effect, to measure the speeds of the winds on the planet.
In other to gather data, researchers used the High Accuracy Radial Velocity Planet Searcher, a telescope in La Silla, Chile. Using the telescope, they were able to measure how fast sodium atoms’ were able to absorb radiation from the host star.
These measurements were taken and measured as the planet rotated around the host start, and on its own axis. As the atmosphere moved towards and away from the Earth, scientists were then able to pick up the Doppler Effect, which allowed them to determine how fast the atmosphere’s velocity was.
Scientists were able to determine the position of the planet and its movements as the planet moved in front of the star and blocked out light. Light from the center of the star will shine more brightly than light towards the edges. Using this information, researchers were able to determine velocities on the opposite sides of the planet, which then allowed the researchers to create a so-called velocity map.
The Doppler effect refers to changes in wavelengths. By measuring changes in wavelengths, scientists were able to determine the velocity of the winds.
The results of the study? The side of the planet facing the star experienced exceptionally strong winds due to the star’s added energy. These winds then blew around to the dark side of the planet. Researchers believe that the star is tidally locked, meaning one side is constantly facing the star, the other constantly in the dark.
The winds seen on this far away gas giant are far faster than anything seen in our own solar system. In fact, the fastest winds in our own galactic neighborhood come in at only about 1,200 MPH. These winds are found on Neptune, and are created by the planet’s high internal temperature. Uranus is also known to experience strong winds.
Gas giants have massive, thick atmospheres filed with a variety of gases. By and large, most of the gas is helium and hydrogen. The presence of other gases, such as methane, gives gas giants their many unique colorations. While some scientists believe that there may be a more solid molten core at the center of many gas giants, their immense atmospheres make it difficult to study happenings beneath the surface.
In fact, the biggest gas giants, like Jupiter, can be thought of as sorts of failed stars. Their composition is similar to a star, but they lack the mass, and thus gravitational force, to achieve self-sustaining fission.
The results were published in the Astrophysical Journal. The study marks a major breakthrough in studying far away planets.