NASA | JPL-Caltech | Spitzer | 2020 Jun 22
Jupiter-size planets orbiting close to their stars have upended ideas about how giant planets form. Finding young members of this planet class could help answer key questions.
For most of human history our understanding of how planets form and evolve was based on the eight (or nine) planets in our solar system. But over the last 25 years, the discovery of more than 4,000 exoplanets, or planets outside our solar system, changed all that.Youngest Hot Jupiter ~ Credits: NASA/JPL-Caltech
This animation illustrates the newly-discovered exoplanet HIP 67522 b,
which appears to be the youngest hot Jupiter ever found.
Among the most intriguing of these distant worlds is a class of exoplanets called hot Jupiters. Similar in size to Jupiter, these gas-dominated planets orbit extremely close to their parent stars, circling them in as few as 18 hours. We have nothing like this in our own solar system, where the closest planets to the Sun are rocky and orbiting much farther away. The questions about hot Jupiters are as big as the planets themselves: Do they form close to their stars or farther away before migrating inward? And if these giants do migrate, what would that reveal about the history of the planets in our own solar system?
To answer those questions, scientists will need to observe many of these hot giants very early in their formation. Now, a new study ... reports on the detection of the exoplanet HIP 67522 b, which appears to be the youngest hot Jupiter ever found. It orbits a well-studied star that is about 17 million years old, meaning the hot Jupiter is likely only a few million years younger, whereas most known hot Jupiters are more than a billion years old. The planet takes about seven days to orbit its star, which has a mass similar to the Sun's. Located only about 490 light-years from Earth, HIP 67522 b is about 10 times the diameter of Earth, or close to that of Jupiter. Its size strongly indicates that it is a gas-dominated planet. ...
TESS Hunt for Young and Maturing Exoplanets (THYME). II.
A 17 Myr Old Transiting Hot Jupiter in the Sco-Cen Association ~ Aaron C. Rizzuto et al