Astronomers found the hottest spot. Their discovery could help them better understand how winds blow on “hot Jupiters” or massive gas giants.
In 2007 astronomers discovered a giant, gaseous exoplanet named CoRot-2b. It orbits its host star in less than three days.
Astronomers often classify planets like this as “hot Jupiters” because of their similar physical properties to Jupiter. They were thought to be tied to their parent stars for years.
Planets like CoRoT-2b can take three days or less to finish an orbit. So it’s no surprise that these hot Jupiters are extremely hot, especially on their daytime side. One side always faces the star, making that area especially warm.
However, let’s get back to the point. Usually, hot Jupiters have strong eastward winds at the equators. It sometimes means the winds displace the hottest area on the planet to just east of the planet’s closest spot to the star. But not on CoRoT-2b. According to new data from NASA’s Spitzer Space Telescope, its hotspot is to the west.
“We’ve previously studied nine other hot Jupiter, giant planets orbiting super close to their star. In every case, they have had winds blowing to the east, as theory would predict. But now, nature has thrown us a curveball. On this planet, the wind blows the wrong way. Since it’s often the exceptions that prove the rule, we are hoping that studying this planet will help us understand what makes hot Jupiters tick,” Nicolas Cowan, an astronomer at McGill University, Canada, and a co-author of a new study, said in a statement.
Since its discovery just over a decade ago, CoRoT-2b continues to intrigue scientists because of its inflated size and the confounding spectrum of light emitted from its surface. The planet is inflated and there are some emissions of light from its surface that astronomers can’t explain.
“Both of these factors suggest there is something unusual happening in the atmosphere of this hot Jupiter,” said lead author Lisa Dang, a McGill doctoral student, in the same statement.
However, scientists have a few possible theories to explain this westward hotspot.
A theory is that the planet spins so slowly that one rotation takes longer to complete than a full orbit of its star. Thus, it would create winds blowing west instead of east. However, it would also disprove existing theories about gravitational relationships between planets and stars in such tight orbits.
The second theory is that the planet’s atmosphere interacts with its magnetic field, thus modifying its winds. If true, it would provide scientists with a rare opportunity to study an exoplanet’s magnetic field.
Other explanation includes that large clouds covering the planet’s eastern side make it appear darker than it otherwise would. This is the least likely because it would dispute our current understanding of how atmospheric circulation on these exoplanets works in the first place.
“We’ll need better data to shed light on the questions raised by our finding,” lead study author and McGill Ph.D. student Lisa Dang says. “Fortunately, the James Webb Space Telescope, scheduled to launch next year, should be capable of tackling this problem. Armed with a mirror that has 100 times the collecting power of Spitzer’s, it should provide us with exquisite data like never before.”
A study based on the research was published in Nature Astronomy on Monday (Jan. 22).
Thumbnail image: Extreme X-ray radiation from this massive sun is evaporating the planet Corot-2b. Credit: Mondolithic.