A super-Earth discovered orbiting BARNARD’S STAR
The frozen rocky world lies just six lightyears away
A super-Earth – with a mass of more than three times our planet – has been discovered orbiting Barnard’s Star, the nearest star to us after Alpha Centauri’s triple-star system.
An international team identified the frozen world using data gathered over 20 years. Dubbed Barnard’s star b, or GJ 599 b, it is the secondclosest known exoplanet, six lightyears away.
The planet is at least 3.2 times as massive as Earth, and it orbits its red dwarf host star once every 233 days. It is the first time a small world so far from its star has been found using the radial velocity method – measuring the wobble in starlight as a planet orbits.
UK planet-hunter Guillem Anglada Escudé, of Queen Mary University, London, co-led the international discovery team, alongside Ignasi Ribas of Spain. Their find is part of the Red Dots project which focuses on red dwarf stars because they are dimmer with less glare to overwhelm faint planets.
Although the distance between the new world and Barnard’s Star is less than half the distance between Earth and the Sun, it gets just a 50th of the warmth. Temperatures are a chilly –170˚C, turning volatile compounds such as water to ice. That is too cold for life as we know it. However, Dr Escudé suggests that other sources of heat or a dense atmosphere might make conditions more hospitable.
Astronomers combined observations using high-precision instruments on telescopes around the world to identify the planet. “The combination of instruments was key to allowing us to cross-check our result,” says Dr Escudé.
There are hints in the data of another giant gas planet, more like Jupiter, taking more than 10 years to orbit Barnard’s Star, but that still has to be confirmed.
The closest Earth-sized rocky planet is Proxima b, which was discovered in 2016.
NASA’s InSight probe landed safely on Mars on 26 November to begin its investigation into what lies deep beneath its surface and to discover how it and other planets formed.
InSight descended through the atmosphere in six and a half minutes to settle on a volcanic plain called Elysium Planitia, near the Martian equator, becoming NASA’s eighth mission to make a successful soft landing on the Red Planet. Unlike Curiosity rover, the previous mission to land in 2012, InSight will not roam the planet, but study Mars from a fixed position.
InSight – short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport – touched down just before 19.53 UT after a 485 million km journey. Within the next six hours, the lander opened its two 2.2m-wide solar panels to collect sunlight and keep its batteries charged. It also sent home the first image of its surroundings, which appeared to be smooth in the immediate area but strewn with rocks in the near distance (see above).
In the days ahead, InSight’s robotic arm is due to be unstowed and extended so that a camera can photograph the ground to help engineers choose where to place its scientific instruments.
These include a dome-shaped seismometer called SEIS (the Seismic Experiment for Interior Structure) which will measure pulses from marsquakes and meteorite impacts. Another instrument, HP3 (the Heat Flow and Physical Properties Probe), is a burrowing probe contributed by the German Aerospace Center (DLR) which will dig 5m into the subsoil to measure heat coming from the planet’s interior and find out whether Mars still has a molten core.
It will take two or three months to deploy the experiments, during which time InSight is due to take readings with its weather sensors and magnetometer. Its mission is scheduled to last 709 sols (Mars days), or nearly two Earth years.
Meanwhile, landing sites have been selected for the next Mars rover missions, launching in 2020. NASA has chosen Jezero Crater, on the edge of giant impact basin Isidis Planitia, while sedimentrich Oxia Planum has been recommended for ESA’s British-built ExoMars rover.