A new study in the Astronomical Journal finds that giant exoplanets with long-period orbits are more likely to be found around young stars that have a disk of dust and debris than those without disks.
This artist’s rendering shows a giant exoplanet causing small bodies to collide in a disk of dust. Image credit: NASA / JPL-Caltech.
The study, led by Caltech researcher Tiffany Meshkat, focused on exoplanets more than five times the mass of Jupiter.
“Our research is important for how future missions will plan which stars to observe. Many planets that have been found through direct imaging have been in systems that had debris disks, and now we know the dust could be indicators of undiscovered worlds,” Dr. Meshkat said.
Dr. Meshkat and her colleagues from Chile, Belgium, UK, and the United States, found the likelihood of finding long-period giant planets is 9 times greater for stars with debris disks than stars without disks.
They combined data from 130 single-star systems with debris disks detected by NASA’s Spitzer Space Telescope, and compared them with 277 stars that do not appear to host disks. The two star groups were between a few million and 1 billion years old. Of the 130 stars, 100 were previously scanned for exoplanets.
As part of the study, the astronomers followed up on the other 30 using the W. M. Keck Observatory in Hawaii and ESO’s Very Large Telescope in Chile.
They did not detect any new planets in those 30 systems, but the additional data helped characterize the abundance of planets in systems with disks.
“It’s possible we don’t find small planets in these systems because, early on, these massive bodies destroyed the building blocks of rocky planets, sending them smashing into each other at high speeds instead of gently combining,” said co-author Dr. Dimitri Mawet, of Caltech and NASA’s Jet Propulsion Laboratory.
On the other hand, giant exoplanets are easier to detect than rocky planets, and it is possible that there are some in these systems that have not yet been found.
“By showing astronomers where future missions such as NASA’s James Webb Space Telescope have their best chance to find giant exoplanets, this research paves the way to future discoveries,” said co-author Dr. Karl Stapelfeldt, of NASA’s Jet Propulsion Laboratory and the agency’s Exoplanet Exploration Program Office.
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Tiffany Meshkat et al. 2017. A Direct Imaging Survey of Spitzer detected debris disks: Occurrence of giant planets in dusty systems. AJ, in press; arXiv: 1710.04185
