An exoplanet discovered just 73 light-years away offers a glimpse of what baby Earth might have looked like if it was trapped in a narrow, scorching orbit with a star.
The world, named HD 63433 d, is a newborn exoplanet orbiting a sun-like star that is slightly larger than Earth. This is the smallest planet we’ve ever discovered, less than 500 million years old, and provides insight into the formation of planets similar to, but not quite like, our world. It’s a precious window.
Earth is the only world on which we know that life exists. Learning about the different ways Earth-like planets form and evolve, especially around stars similar to the Sun, will help scientists uncover the ingredients that allow life to emerge elsewhere in the universe. Helpful.
HD 63433 d is both very similar to Earth and very different at the same time, which means great opportunities. And it differs from Earth in some very exciting extremes.
“It’s a useful planet because it could resemble early Earth.” says astrophysicist Melinda Soares-Furtado. from the University of Wisconsin-Madison led the research in collaboration with astronomer Benjamin Capistrant of the University of Florida.
“Even if it’s orbiting very closely, we can use the tracking data to find evidence of outgassing and atmospheric loss, which could be important constraints on how the terrestrial world evolves. You can look for it, but the similarities end there, and they end dramatically.”
This Earth-sized world was discovered during a survey using the TESS Exoplanet Search telescope, which stares at stars and searches for faint, regular dips in starlight that indicate the presence of orbiting exoplanets. By measuring the various effects an exoplanet has on starlight, astronomers can determine its size and mass.
HD 63433 is a yellow dwarf star with approximately the same size and mass as the Sun and a similar temperature profile. However, the age of the Sun is much younger than 4.5 billion years, just over 400 million years. The HD 63433 is just a baby from a superior perspective. And so are the exoplanets orbiting it. So far, her two mini-Neptunes discovered in 2020 and her three exoplanets in HD 63433 d have been discovered.
Orbital data (data that is submerged in starlight as it orbits) show that HD 63433 d is 1.1 times the radius of Earth. Although its mass is not yet known, its physical size strongly suggests Earth’s composition, a rocky world like Earth, Mars, and Venus.
Exoplanets orbit their stars in extremely tight orbits once every 4.2 days. This means that HD 63433 d and its star are very close together, and HD 63433 d is likely tidally locked, with one side always facing the star. One hemisphere always bears the brunt of the star’s heat, so its surface is likely a permanent ocean of molten rock, with daytime temperatures of 1,570 degrees Kelvin (1,297 degrees Celsius, or 2,366 degrees Fahrenheit). Scientists say there is.
It’s basically a giant ocean of lava.
Of course, the Earth has never been this close to the Sun, but it may have reached temperatures similar to the Sun. 2,300 Kelvinfollowing an impact that shattered part of the planet and formed the moon.
There’s still a lot we don’t know about HD 63433d. The research team hopes follow-up surveys will tell them a little more about it, including its mass. This allows scientists to calculate its density, which tells us what the exoplanet is made of. You might even be able to determine if there’s a vibe there, and what that vibe includes.
“This is our solar backyard. That’s very exciting.” Soares Furtado says. “What information does a star that is so close and has such a dense system around it give us? Among perhaps 100 similar stars in this young star cluster to which it belongs? What kind of information is useful when searching for planets? ”
HD 63433 d is the closest known exoplanet to Earth, orbiting a young star with a radius similar to Earth’s. There are many things this world has not yet taught us. We hope to have more information about that in the coming months.
This study astronomical journal.