There’s an intriguing exoplanet out there – 400 light-years out there – that is so tantalizing that astronomers have been studying it since its discovery in 2009.
There’s an intriguing exoplanet out there – 400 light-years out there – that is so tantalizing that astronomers have been studying it since its discovery in 2009. A year for WASP-18 b, one orbit around its star (slightly larger than our Sun), takes just 23 hours. There’s nothing like it in our solar system. In addition to observatories on the ground, NASA’s Hubble, Chandra, TESS, and Spitzer space telescopes have all observed WASP-18 b, an ultra-hot gas giant 10 times more massive than Jupiter. Now astronomers have taken a look with NASA’s James Webb Space Telescope and the ‘‘firsts’’ keep coming.
The discovery: Scientists identified water vapor in the atmosphere of WASP-18 b, and made a temperature map of the planet as it slipped behind, and reappeared from, its star. This event is known as a secondary eclipse. Scientists can read the combined light from star and planet, then refine the measurements from just the star as the planet moves behind it.
The same side, known as the dayside, of WASP-18 b always faces the star, just as the same side of the Moon always faces Earth. The temperature, or brightness, map shows a huge change in temperature – up to 1,000 degrees – from the hottest point facing the star to the terminator, where day and night sides of the tidally-locked planet meet in permanent twilight.
Read more at NASA's Exoplanet Exploration Program
Image: WASP-18 b, seen in an artist concept, is a gas giant exoplanet 10 times more massive than Jupiter that orbits its star in just 23 hours. Researchers used NASA’s James Webb Space Telescope to study the planet as it moved behind its star. Temperatures there reach 5,000 degrees Fahrenheit (2,700 C). Credit: NASA/JPL-Caltech (K. Miller/IPAC)