Younger version of Jupiter provides clues to planet formation
It's likely not the first time you'll hear scientists compare an exoplanet to Jupiter. According to a team of astronomers, though, this one called the 51 Eridani b isn't only similar in size -- it's "very much what models suggest Jupiter was like in its infancy." 51 Eri b, which has an atmosphere rich in methane, was spotted using the Gemini Planet Imager's new instrument mounted on the Gemini South Telescope in Chile. The instrument is as big as a small car, was made to filter out atmospheric turbulence and was optimized to spot faint planets next to bright stars. This exoplanet, for instance, is a million times less luminous than its host star, which is only 20 million years old or so; our own sun is already 4.5 billion years old.
So, how exactly does 51 Eri b resemble the biggest planet in our solar system? To start with, it's only twice the size of Jupiter, whereas the ones discovered in the past were around five times as big. Also, scientists suspect that it formed the same way the gas giants in our solar system did. The other Jupiter-like exoplanets are all too hot, but 51 Eri b has a temperature of 800 degrees Fahrenheit and is considered "cold" like Jupiter, which has an average temp of 234 degrees.
It could be because just like our gas giants, it first formed a rocky core for a few million years before it started attracting gases. Other planets are likely hot, because they pulled in gases too quickly. The astronomers are hoping that this young exoplanet can help them better understand how our gas giants formed around the sun. But before that, they hope to spot it again in September as it reappears from behind its star -- just to make sure it's really a planet.
[Image credit: Danielle Futselaar & Franck Marchis/SETI Institute]
