Venus-like exoplanet discovered

The hunt for exoplanets continues in the hope of finding Earth's 'twin'. The latest discovery is of a Venus-like exoplanet cool enough to potentially host an atmosphere and close enough to study in detail.

exoplanet MAIN

The latest addition to known exoplanets could provide a new opportunity to study a rocky, Venus-like planet in detail. Credit: Dana Berry

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The hunt for exoplanets has uncovered a Venus-like rocky exoplanet just 39 lightyears away from Earth, meaning it is close enough to study in detail.

GJ 1132b is hot as an oven, yet cool enough to potentially host an atmosphere.

It orbits a red dwarf that is one fifth the size of the Sun every 1.6 days at a distance of just over 2.2 million kilometres.

The planet’s temperature is about 230°C, meaning any water would have boiled off, but it is still cool enough to host an atmosphere.

It is also much cooler than any other rocky exoplanet yet discovered.

The key discovery is that the planet is so close to Earth that any atmosphere would be able to be studied with the Hubble Space Telescope.

“Our ultimate goal is to find a twin Earth, but along the way we’ve found a twin Venus,” says astronomer David Charbonneau of the Harvard-Smithsonian Center for Astrophysics (CfA).

“We suspect it will have a Venus-like atmosphere too, and if it does we can’t wait to get a whiff.”

“This planet is going to be a favourite target of astronomers for years to come,” adds lead author Zachory Berta-Thompson of the Massachusetts Institute of Technology (MIT).

“If we find this pretty hot planet has managed to hang onto its atmosphere over the billions of years it’s been around, that bodes well for the long-term goal of studying cooler planets that could have life.

We finally have a target to point our telescopes at, and [can] dig much deeper into the workings of a rocky exoplanet and what makes it tick.”

GJ 1132b was discovered by the MEarth-South array, which consists of eight robotic telescopes at the Cerro-Tololo Inter-American Observatory in Chile.

The array is specifically aimed at hunting for exoplanets orbiting red dwarfs.

It does so using the transit method, which involves looking for the dimming of light from a star in order to detect a planet passing by it in orbit.

MEarth-South detected such a transit in order to spot GJ 1132b and additional observations were carried out by both the array and the Magellan Clay telescope in Chile.

The team were also able to measure the red dwarf’s wobble, caused by the gravitational pull of the planet, and used this to determine the planet’s mass.

Through these observations, the team calculated that GJ 1132b is 16 per cent larger than Earth with a diameter of about 9,200 miles.

Its mass is 60 per cent greater than Earth and it has a rocky surface.

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The team now plan to carry out further observations with the Hubble and Spitzer space telescopes to study the planet in more detail, but also to hunt for any possible planetary siblings that may also be orbiting the star.