At a distance of just 39 light years is an exoplanet called GJ 1132B that astronomers say is 1.4 times the size of our planet and has atmosphere.
The discovery was made by a team of astronomers including those from the Max Planck Institute for Astronomy in Germany. The latest discovery is the first ever time astronomers have directly detected atmosphere around a planet with mass and radius close to Earth’s mass and radius (1.6 Earth masses, 1.4 Earth radii).
Astronomers imaged the star GJ 1132 and measured the slight decrease in its brightness as the planet GJ 1132B and its atmosphere absorbed some of the starlight while passing directly in front of their host star. GJ 1132b is a transiting planet: From the perspective of an observer on Earth, it passes directly in front of its star every 1.6 days, blocking some of the star’s light. The size of stars like GJ 1132 is well known from stellar models. From the fraction of starlight blocked by the planet, astronomers can deduce the planet’s size – in this case around 1.4 times the size of the Earth.
The team used the GROND imager at the 2.2-m ESO/MPG telescope of the European Southern Observatory in Chile to observe the planet simultaneously in seven different wavelength bands.
The new observations showed the planet to be larger at one of the infrared wavelengths than at the others.This suggests the presence of an atmosphere that is opaque to this specific infrared light (making the planet appear larger) but transparent at all the others.Different possible versions of the atmosphere were then simulated by team members at the University of Cambridge and the Max Planck Institute for Astronomy.
According to those models, an atmosphere rich in water and methane would explain the observations very well.Observations to date do not provide sufficient data to decide how similar or dissimilar GJ 1132b is to Earth. Possibilities include a “water world” with an atmosphere of hot steam, researchers said. The research was published in the Astronomical Journal.