We’ve known since the 1990s that massive, Jupiter-like worlds can exist snuggled up to their host stars. What we haven’t known is how they get there. It could be they formed there or migrated there at some point in their solar system’s history. It could even be all of the above. To understand these systems, we need examples of young stars with young planets so we can see what is possible.
And finally, we have one example. HIP 67522b is a hot Jupiter found in data from NASA’s Transiting Exoplanet Survey Satellite (TESS) that is orbiting its star every seven days. That star is only 17-million-years old, and that makes this a young planet. While we still can’t know if the world formed there or migrated there early in the star system’s history, this singular example does tell us that not all hot Jupiters migrate there a billion or more years into a solar system’s evolution. It is a start. One object can be the start of an awful lot of science, but here is hoping they find many more examples quickly.
“TESS Hunt for Young and Maturing Exoplanets (THYME). II. A 17 Myr Old Transiting Hot Jupiter in the Sco-Cen Association,” Aaron C. Rizzuto, 2020 June 22, Astronomical Journal (Preprint on arxiv.org)