A new 'secret' planetary system that includes three super-Earths and one outer giant planet has been discovered by astronomers at a distance of just 21 light years from Earth.
Named HD219134, the system in the constellation Cassiopeia hosts one outer giant planet and three inner superEarths, one of which transits in front of the star and has a density similar to the Earth's. It is by far the closest transiting planet known today, researchers said.HARPS-N, designed and built by an international consortium and installed at the Telescopio Nazionale Galileo in Spain's La Palma Island unveiled the exceptional planetary system around HD219134.
The star, a 5th magnitude K dwarf, slightly colder and less massive than our Sun, is so bright that we can follow it with a naked eye from dark skies, next to one leg of the W-shape Cassiopeia constellation, all year round in our boreal hemisphere, researchers said.
The cortege of planets composed of three mostly rocky super-Earths and an outer giant planet, a configu ration reminiscent of our own Solar System, they said. "When the first HARPS-N ra dial-velocity measurement indicated the presence of a 3 day planet around HD219134 we asked NASA for Spitzer space telescope to check for a potential transit of the plan et in front of the star, a mini eclipse, that would allow us to measure the size of the planet," said Ati Motalebi, astronomer at University of Geneva and lead author of the paper describing the discovery.
The mass of the planet obtained from the groundbased radial velocities, combined with the planet radius derived from space observations with Spitzer, yield the mean density of the planet.HD219134b was found to be 4.5 times more massive than the Earth and 1.6 times larger, what planet hunters call a super-Earth. Its mean density is close to the density of the Earth, suggesting a possibly similar composition as well. The team also discovered three additional longer-period planets in the system from the HARPS-N radial velocities.
Nasa ready to halt traffic jams at Mars
With five active spacecrafts now orbiting the Red Planet, including one from India, Nasa has beefed up traffic monitoring, communication and manoeuvre to ensure that the Mars orbiters do not collide with one another. The newly-enhanced collision-avoidance system accurately warns if two orbiters approach each other too closely. Currently, all the Mars orbiters use the communication and tracking services of Nasa's Deep Space Network, which helps bring trajectory information together and engineers can run computer projections of future trajectories out to a few weeks ahead for comparisons. "Previously, collision avoidance was coordinated between the Odyssey and MRO navigation teams. There was a less possibility of an issue," Nasa's Robert Shotwell said.