In what appears to be a record, two different teams of astronomers have confirmed the existence of a seventh planet orbiting a dwarf star 2,500 light-years away. And incredibly, all seven planets are caught in a tight orbit closer than the Earth’s distance to the Sun.
Astronomers working at the European Southern Observatory (ESO) in Chile have discovered seven planets orbiting the star Gliese 667C.
Two exoplanets have been discovered in the star’s habitable zone, which has just the right range of distance where liquid water can exist on a planet’s surface.
A super-Earth is an extrasolar planet with a mass higher than Earth’s, but substantially below the mass of the Solar System’s smaller gas giants Uranus and Neptune, which are both more or less 15 Earth masses.
The term super-Earth refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability.
Astronomers at the European Southern Observatory in Chile found out that 40 per cent of red dwarves are orbited by super-Earths. Red Dwarfs are by far the most common type of star in the Milky Way galaxy, so there might be tens of billions of such planets in our galaxy alone.
If you really hate living here on Earth the next best place to be is just a hop, skip, and a jump away!
But research to appear in Astronomy and Astrophysics has found three more - among them a “super-Earth” seven times our planet’s mass, in the habitable zone where liquid water can exist.
Many more observations will be needed to confirm any other similarities.
But the find joins an ever-larger catalogue of more than 800 known exoplanets, and it seems only a matter of time before astronomers spot an “Earth 2.0” - a rocky planet with an atmosphere circling a Sun-like star in the habitable zone.
HD 40307, which lies 42 light-years away, is not particularly Sun-like - it is a smaller, cooler version of our star emitting orange light.
But it is subtle variations in this light that permitted researchers working with the Rocky Planets Around Cool Stars (Ropacs) network to find three more planets around it.
NASA’s Kepler mission has confirmed its first planet in the “habitable zone,” the region where liquid water could exist on a planet’s surface. Kepler also has discovered more than 1,000 new planet candidates, nearly doubling its previously known count. Ten of these candidates are near-Earth-size and orbit in the habitable zone of their host star. Candidates require follow-up observations to verify they are actual planets.
The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our sun. The planet is about 2.4 times the radius of Earth. Scientists don’t yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets.
A diagram to help people envisage how the Kepler-22 system compares to our arrangement of planets.
I will take this opportunity to emphasize once again that it is not yet possible to know whether this planet (or the other candidates) are Earth like; we only know they are Earth sized (in the case of Kepler-22b slightly larger than the Earth) and are in orbits that could allow for liquid water on their surfaces.
Also, the number of Kepler candidate planets are multiplying rapidly. Our galaxy is likely awash with planets. Kepler satellite’s main goal was to get a statistical count of planets and their distribution, and it is performing magnificently. Hopefully Congress can find the few million dollars to fund an extended mission while the satellite is still operational.
Scientists have tracked down another goldilocks planet 31 light-years from Earth, and according to astronomers it has some strong points in its favor when it comes to the possibility of harboring the ingredients for life. HD85512b orbits an orange dwarf in the constellation Vela, and it’s just the right distance from the sun—and just the right mass—to rank among the most Earth-like planets ever discovered.
In conjunction with the 217th meeting of the American Astronomical Society, NASA is giving several presentations on the latest findings from their Kepler team.
The news release:
NASA’s Kepler mission confirmed the discovery of its first rocky planet, named Kepler-10b. Measuring 1.4 times the size of Earth, it is the smallest planet ever discovered outside our solar system.
The discovery of this so-called exoplanet is based on more than eight months of data collected by the spacecraft from May 2009 to early January 2010.
“All of Kepler’s best capabilities have converged to yield the first solid evidence of a rocky planet orbiting a star other than our sun,” said Natalie Batalha, Kepler’s deputy science team lead at NASA’s Ames Research Center in Moffett Field, Calif., and primary author of a paper on the discovery accepted by the Astrophysical Journal. “The Kepler team made a commitment in 2010 about finding the telltale signatures of small planets in the data, and it’s beginning to pay off.”
Kepler’s ultra-precise photometer measures the tiny decrease in a star’s brightness that occurs when a planet crosses in front of it. The size of the planet can be derived from these periodic dips in brightness. The distance between the planet and the star is calculated by measuring the time between successive dips as the planet orbits the star.
Kepler is the first NASA mission capable of finding Earth-size planets in or near the habitable zone, the region in a planetary system where liquid water can exist on the planet’s surface. However, since it orbits once every 0.84 days, Kepler-10b is more than 20 times closer to its star than Mercury is to our sun and not in the habitable zone.
Kepler-10 was the first star identified that could potentially harbor a small transiting planet, placing it at the top of the list for ground-based observations with the W.M. Keck Observatory 10-meter telescope in Hawaii.
Scientists waiting for a signal to confirm Kepler-10b as a planet were not disappointed. Keck was able to measure tiny changes in the star’s spectrum, called Doppler shifts, caused by the telltale tug exerted by the orbiting planet on the star.
“The discovery of Kepler 10-b is a significant milestone in the search for planets similar to our own,” said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington. “Although this planet is not in the habitable zone, the exciting find showcases the kinds of discoveries made possible by the mission and the promise of many more to come,” he said.
Knowledge of the planet is only as good as the knowledge of the star it orbits. Because Kepler-10 is one of the brighter stars being targeted by Kepler, scientists were able to detect high frequency variations in the star’s brightness generated by stellar oscillations, or starquakes. This analysis allowed scientists to pin down Kepler-10b’s properties.
There is a clear signal in the data arising from light waves that travel within the interior of the star. Kepler Asteroseismic Science Consortium scientists use the information to better understand the star, just as earthquakes are used to learn about Earth’s interior structure. As a result of this analysis, Kepler-10 is one of the most well characterized planet-hosting stars in the universe.
That’s good news for the team studying Kepler-10b. Accurate stellar properties yield accurate planet properties. In the case of Kepler-10b, the picture that emerges is of a rocky planet with a mass 4.6 times that of Earth and with an average density of 8.8 grams per cubic centimeter — similar to that of an iron dumbbell.
Ames manages Kepler’s ground system development, mission operations and science data analysis. NASA’s Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development.
Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data.
NASA prepared a video:
The planet, while only being a little larger than the Earth in radius, is not very Earth-like. Think of it as more of an ultra-Mercury. It would be very hot on the side that always faces its star, probably molten. It is denser than the Earth (which is mostly made of iron but has plenty of lighter elements) and the surface gravity would be twice that of Earth’s (so you’d weigh over twice as much at the surface!)
Still, this detection proves that Kepler can indeed find Earth-sized planets.
Note that the planet, like all of Kepler planet candidates, needs to go through a confirmation process. This is slow as it takes (large) ground telescopes to determine if the signal is a false positive (likely due to background binary stars behind the candidate solar system, from our perspective.)
As such, actual planet announcements are running a full year behind the original Kepler data collection. We will be hearing of more Kepler discoveries for years to come, including planets in their stars’ habitable zones!
As I type this more presentations by the Kepler team are ongoing in Seattle:
And there will be a featured presentation on Thursday summarizing some of the scientific findings:
This is the new golden age of astronomy!
Summary: Astronomers are re-thinking the requirements that need to be met for an exoplanet to be considered ‘habitable.’ A new simulation of the Gliese 581 system is helping astrobiologists refine their search for Earth-like worlds in the Universe. Gleise 581 recently made news because a planet could be orbiting within the system’s habitable zone.