A team of astronomers has discovered a planet that is closer and younger than any other Earth-sized planet previously identified.
The discovered object is an exceptionally hot world, whose proximity to our planet and a star like our Sun makes it a unique opportunity to study planetary evolution.
The new planet is described in a new study published this week in the Astronomical Journal. Melinda Soares-Furtado, a NASA Hubble Fellow at the University of Wisconsin-Madison who will begin work as an astronomy professor at the university in the fall, and Benjamin Capistrant, a recent graduate of UW-Madison and now a graduate student at the University of Florida, led the Study together with co-authors from all over the world.
“It's a useful planet because it can be like a primitive Earth,” says Soares-Furtado.
This is what scientists know about the planet
- The planet is called HD 63433d and is the third planet to orbit a star called HD 63433.
- HD 63433d is so close to its star that it orbits it every 4.2 days.
- “Although its orbit is very close, we can use the tracking data to look for evidence of outgassing and atmospheric loss, which could represent important constraints on the evolution of terrestrial worlds,” says Soares-Furtado. “But that’s where the similarities end, and they end spectacularly.”
- Because of its orbit, astronomers are relatively certain that HD 63433d is tidally locked, meaning that one side is constantly aligned with its star.
- This side can reach a brutal 2,300 degrees Fahrenheit and lava can flow, while the opposite side is always dark.
What you need to know about the planetary star
- HD 63433 is about the same size and type of star as our sun, but is less than a tenth as old as our sun (at about 400 million years).
- The star is located about 73 light-years from our Sun and is one of the group of stars that move together to form the constellation Ursa Major, which includes Ursa Major.
- “On a dark night in Madison,” says Soares-Furtado, “you could see (HD 63433) through good binoculars.”
How scientists found the planet
The study's authors collaborate on a planet-hunting project called THYME. In 2020, they used data from NASA's Transiting Exoplanet Survey satellite to identify two mini-Neptune-sized planets orbiting HD 63433. Since then, TESS has taken four more looks at the star, collecting enough data for researchers to discover HD 63433d star and satellite.
The researchers, including UW-Madison graduate student Andrew C. Nine, undergraduate student Alyssa Jankowski and UW-Madison astronomy professor Juliette Becker, believe there is much to learn from HD 63433d.
The planet is in a unique situation for its exploration. Its young star is visible from both the Northern and Southern hemispheres, increasing the number of instruments that can be trained in the system, such as the South African Large Telescope or the WIYN Observatory in Arizona (both developed by UW- Madison helped design and build). .
In addition, the star is several orders of magnitude closer than many others that Soares-Furtado has studied, potentially allowing the development of new methods for studying gases escaping from the planet's interior or measuring its magnetic field.
“It’s our solar backyard, and that’s very exciting,” Soares-Furtado says. “What information can a star so close with such a populated system around it give us? How will it help us search for planets among the other 100 similar stars in this young group to which it belongs?
TESS hunt for young and maturing exoplanets (THYME). XI. An Earth-sized planet orbiting a nearby Sun-like host in the 400 Myr Ursa Major motion group