The warm Neptunian exoplanet, called GJ 3470b (Gliese 3470b), is 96 light years away and orbits a 2 billion year old red dwarf star in the direction of the constellation Cancer.
Artist's impression of the warm-Neptunian exoplanet GJ 3470b. Image courtesy of the University of Wisconsin-Madison Department of Astronomy.
First discovered in 2012, GJ 3470b is the lightest and coolest (over 325 degrees Celsius, or 600 degrees Fahrenheit) exoplanet containing sulfur dioxide.
The compounds are likely a sign of active chemistry taking place in the planet's atmosphere, as radiation from a nearby star explosively breaks down hydrogen sulfide components, which then seek out new molecular partners.
“We never expected to see sulfur dioxide on such a small planet, so finding this new molecule in an unexpected place is exciting because it gives us new ways to understand how these planets formed,” said Professor Thomas Beatty of the University of Wisconsin-Madison.
“And small planets are particularly interesting because their composition depends heavily on how the planet-formation process happened.”
Prof Beatty and his colleagues hope that by observing what exoplanets contain, they can shed light on the principles of planet formation and do just that.
“The discovery of sulphur dioxide on a small planet like GJ 3470b adds another important item to the list of ingredients for planet formation,” Prof Beatty said.
In the case of the GJ 3470b, there are also other interesting features that could help round out that recipe.
The planet orbits the star and passes nearly over the star's pole, meaning that it orbits at a 90 degree angle to the expected orbit of a planet in this system.
The moon is also incredibly close to its star, close enough that light from the star would blow a lot of GJ 3470b's atmosphere out into space.
The team says the planet may have lost around 40% of its mass since it formed.
The misaligned orbit suggests that GJ 3470b was once somewhere else in the system, and at some point, the planet became caught in the gravity of another planet, pulling it into a new orbit and eventually settling in a different neighborhood.
“The migration history that led to this polar orbit and how it has lost so much mass are things we don't typically know about other exoplanet targets that we study,” Prof Beattie said.
“These are important steps in the recipe that created this particular planet, and they help us understand how planets like this one are made.”
“Further analysis of the components remaining in the planet's atmosphere may help us understand why planets like GJ 3470b became so appetizing.”
This month, the authors 244th Meeting of the American Astronomical Society In Madison, Wisconsin.
Source: www.sci.news
