W. M. Keck Observatory | California Institute of Technology
McDonald Observatory | University of Texas, Austin | 2019 Aug 27
Three times the mass of Jupiter, a first-of-its-kind planet swings around its star on bizarre path
Astronomers have discovered a planet three times the mass of Jupiter that travels on a long, egg-shaped path around its star. If this planet were somehow placed into our own solar system, it would swing from within our asteroid belt to out beyond Neptune. Other giant planets with highly elliptical orbits have been found around other stars, but none of those worlds were located at the very outer reaches of their star systems like this one.The Strange Orbit of HR 5183 bClick to play embedded YouTube video.
Credit: W. M. Keck Observatory/Adam Makarenko
“This planet is unlike the planets in our solar system, but more than that, it is unlike any other exoplanets we have discovered so far,” says Sarah Blunt ... “Other planets detected far away from their stars tend to have very low eccentricities, meaning that their orbits are more circular. The fact that this planet has such a high eccentricity speaks to some difference in the way that it either formed or evolved relative to the other planets.”
The planet was discovered using the radial velocity method, a workhorse of exoplanet discovery that detects new worlds by tracking how their parent stars “wobble” in response to gravitational tugs from those planets. However, analyses of these data usually require observations taken over a planet’s entire orbital period. For planets orbiting far from their stars, this can be difficult: a full orbit can take tens or even hundreds of years. ...
The astronomers have been watching HR 5183 since the 1990s, but do not have data corresponding to one full orbit of the planet, called HR 5183 b, because it circles its star roughly every 45 to 100 years. The team instead found the planet because of its strange orbit. ...
Radial Velocity Discovery of an Eccentric Jovian World Orbiting at 18 au ~ Sarah Blunt et al
- arXiv.org > astro-ph > arXiv:1908.09925 > 26 Aug 2019