Scientists have found first direct evidence of existence of atmosphere around an exo-planet located some 39 light years away from Earth.
The exoplanet is GJ 1132b orbiting its host star GJ 1132, which is a red dwarf star, in the southern constellation Vela. The work was carried out by scientists at Max Planck Institute for Astronomy in Germany and colleagues. Astronomers imaged the planet’s host star, GJ 1132, and measured the slight decrease in brightness as the planet and its atmosphere absorbed some of the starlight while passing directly in front of their host star.
The GJ 1132b is said to be a super Earth with 1.6 Earth masses and 1.4 Earth radii. Scientists say that the detection of an atmosphere around such a planet is the first time an atmosphere has been detected around a planet with a mass and radius close to Earth’s mass and radius. 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.
Using the GROND imager at the 2.2-m ESO/MPG telescope of the European Southern Observatory in Chile, scientists observed 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.
“GJ 1132b provides a hopeful counterexample of an atmosphere that has endured for billion of years. Given the great number of M dwarf stars, such atmospheres could mean that the preconditions for life are quite common in the universe,” they said.
Researchers added that unfortunately, this planet is too hot to be considered habitable, so it does not have much bearing on our search for extraterrestrial life, although it confirms the detection of atmospheres on small planets.
The research was published in the Astronomical Journal.