Rocky “Super-Earth” Found Orbiting One of our Galaxy’s Oldest Stars

A rocky “super-Earth” that is orbiting one of the oldest stars in our Milky Way Galaxy has been discovered. The exoplanet, which has been named TOI-561b, is approximately 50% larger than Earth.

The planet was discovered by experts analyzing data collected by NASA’s Transiting Exoplanet Survey Satellite (TESS) as well as the W.M. Keck Observatory in Hawaii. The system is located about 280 light-years away from us and while two other planets have also been found orbiting the host star (in addition to TOI-561b), they are much too large, not dense enough, and probably gaseous so they wouldn’t be rocky worlds.

TOI-561b zips around its host star at an incredibly fast speed as it takes less than 12 hours for it to complete a full orbit. Since it whips around the star at such a close proximity, the exoplanet has an exceptionally hot surface temperature of about 3,140 degrees Fahrenheit (or 1,726 degrees Celsius). With that being said, I think it’s safe to say that the planet does not host any type of life.

One interesting thing they did find out about the exoplanet is that its density is very similar to Earth’s. In a UC Riverside statement, Stephen Kane, who is a planetary astrophysicist from the University of California, Riverside, and a co-author of the study, explained, “This is surprising, because you'd expect the density to be higher.” “This is consistent with the notion that the planet is extremely old.”

In fact, the exoplanet could be as old as 10 billion years. Even its host star, called TOI-561, is extremely old and is located in an area called the galactic thick disk where the stars contain much less heavy elements than others that are in our galaxy. Since the Milky Way Galaxy is approximately 13.6 billion years old and TOI-561 could be as old as 10 billion years, that’s incredibly interesting to think that specific system is almost as old as the galaxy. To put this into better perspective, our sun is only 4.5 billion years old.

Lauren Weiss, who is a postdoctoral fellow at the University of Hawaii and the lead author of the study, noted, “This planet formed at a time when the majority of stars in our galaxy were first beginning to shine.” She went on to say, “TOI-561b is one of the oldest rocky planets yet discovered.” “Its existence shows that the universe has been forming rocky planets almost since its inception 14 billion years ago.”

Kane added, “Though this particular planet is unlikely to be inhabited today, it may be a harbinger of many rocky worlds yet to be discovered around our galaxy's oldest stars.” And the search continues... (An artist’s impression of what TOI-561b looks like can be seen here.)

Their research was published in The Astronomical Journal where it can be read in full.