Sulphur discovered in atmosphere of unusual gas dwarf exoplanet

Sulphur discovered in atmosphere of unusual gas dwarf exoplanet

An unusual gas dwarf exoplanet has been discovered with sulphur in its atmosphere. The exoplanet is providing scientists with valuable insights on planet formation.

Illustration of GJ 3470 b. (Image Credit: Department of Astronomy, UW–Madison).

New Delhi: Astronomers had long assumed that all planetary systems would follow the template of the Solar System, with large gas giants occupying the outer Solar System, with small, terrestrial or rocky worlds residing in the inner Solar System. The primary method for astronomers for hunting down exoplanets is looking for telltale dips in light as the planet passes in front of the host star from the vantage point of the Earth, in events known as transits.

Over 5,500 exoplanets have been discovered so far, most of them through the transit method, which favours the discovery of particularly large planets in close orbits around the host star, especially small host stars, as larger planets block out more light from smaller stars. Astronomers have discovered plenty of gas giants in close orbits around host stars, but not Neptune-sized exoplanets. This lack of worlds straddling the mass gap between Earth and Jupiter in close orbits around their stars is known as the Neptunian desert.

Exoplanet GJ 3470 b

GJ 3470 b was discovered in 2012, and is about half the size of Neptune, containing 14times the mass of Earth, orbiting its host star once every 3.3 days. This exoplanet falls neatly within the Neptunian Desert, and characterising such worlds can provide scientists with valuable insights on the formation and evolution of star systems, as well as the physical processes driving exoplanet assembly.

GJ 3470 b is at a distance of 96 lightyears from the Earth in the constellation of Cancer. Researchers have discovered water, carbon dioxide, methane and sulphur dioxide in the atmosphere of the unusual exoplanet, which is the lightest and coldest exoplanet known to contain sulphur in its atmosphere. The planet is also orbits the star at a 90 degree angle to the expected orbits of planets, suggesting a complex formation history.

The research were presented at the 244th meeting of the American Astronomical Society. One of the researchers, Thomas Beatty says, “We didn’t think we’d see sulphur dioxide on planets this small, and it’s exciting to see this new molecule in a place we didn’t expect, since it gives us a new way to figure out how these planets formed. And small planets are especially interesting, because their compositions are really dependent on how the planet-formation process happened.”