Super Venus in our cosmic neighborhood
Wolf 437, also called Gliese 486, is a red dwarf fairly close to the Sun – just 26 light-years away. What makes it interesting is a planet that astronomers now present in Science. Gliese 486 b moves around its parent star in a circular orbit within 1.5 days and at a distance of only 2.5 million kilometers (Earth: 150 million kilometers). Since its rotation around its own axis always takes the same time, the planet always turns the same side to its sun – similar to the moon to the earth.
Although the star Gliese 486 is much fainter and cooler than the Sun, its proximity to the planet heats its surface to at least 430 degrees Celsius. As a result, the surface of Gliese 486 b likely resembles that of Venus, with a hot and arid landscape covered with glowing lava flows. Calculations also show that the exoplanet has a composition similar to Venus and Earth, including a metallic core. Those who spend time on Gliese 486 b also feel an attractive force that is about 70 percent stronger than that on our home planet.
Unlike Venus, however, Gliese 486 b may have only a thin atmosphere – or none at all. Model calculations provide both scenarios, since planetary gas envelopes can evaporate over time under stellar irradiation. On the other hand, the planet’s gravity helps maintain them. It is difficult to determine the balance between these two factors mentioned above.
«The discovery of Gliese 486 b was a stroke of luck. Another 100 degrees hotter, and the entire surface of the planet would be lava. Its atmosphere would be vaporized rock,» says José A. Caballero of the Centro de Astrobiología (CSIC-INTA, Spain) and co-author of the study. «On the other hand, if Gliese 486 b were a hundred degrees colder, it would be unsuitable for further observations.»
Because of its close proximity, astronomers now hope to be able to view it more closely with future telescopes.