Planets around stars are the rule rather than the exception

Jan 12, 2012

There are more exoplanets further away from their parent stars than originally thought, according to new astrophysics research.

In a new paper appearing in the Jan. 12 edition of the journal, Nature, Kem Cook as part of an international collaboration, analyzed microlensing data that bridges the gap between a recent finding of planets further away from their parent stars and observations of planets extremely close to their . The results point to more resembling our solar system rather than being significantly different.

Gravitational microlensing occurs when light from a source star is bent and focused by gravity as a second object (the lens star), which passes between the source star and an observer on Earth. A planet rotating around the lens star will produce an additional deviation in the microlensing. The first observations were made by the Massive Astrophysical Compact Halo Object (MACHO) collaboration, led by Livermore scientists.

The new research also determines that a large fraction of planets have orbital distances from 0.5 to 10 sun-Earth distances. In the past, using the technique, most found were like Jupiter and Saturn that orbited stars that were much closer to them than the sun is to Earth.

An is a planet outside our solar system. Over the past 16 years, astronomers have detected more than 700 confirmed exoplanets and have started to probe the spectra and atmospheres of these worlds. While studying the properties of individual exoplanets is undeniably valuable, a much more basic question remains: how commonplace are planets in the Milky Way?

The team found that approximately 17 percent of stars host Jupiter-mass planets. However, cool-Neptunes and super-Earths are more common, occurring 52 percent and 62 percent, respectively, of the time.

Gravitationally microlensing is very rare. In fact, fewer stars than one per million undergo micolensing at any time.

The team's result is consistent with every star of the Milky Way, hosting, on average, one planet or more in an orbital distance range of 0.5 to 10 sun-Earth distances.

"Our measurements confirm that low-mass planets are very common and the number of planets increases with decreasing planet mass, in an agreement with the predictions of the core accretion scenario of planet formation," Cook said. "Planets around stars in our galaxy appear to be the rule rather than the exception."

"We used to think that the Earth might be unique in our galaxy. But now it seems that there are literally billions of planets with masses similar to Earth orbiting stars in the Milky Way," concludes Daniel Kuba, of the European Southern Observatory and co-lead author of the paper .

Explore further: Image: Galactic wheel of life shines in infrared

Provided by DOE/Lawrence Livermore National Laboratory

4.4 /5 (9 votes)

Related Stories

Recommended for you

Image: Galactic wheel of life shines in infrared

13 hours ago

It might look like a spoked wheel or even a "Chakram" weapon wielded by warriors like "Xena," from the fictional TV show, but this ringed galaxy is actually a vast place of stellar life. A newly released ...

New window on the early Universe

Oct 22, 2014

Scientists at the Universities of Bonn and Cardiff see good times approaching for astrophysicists after hatching a new observational strategy to distill detailed information from galaxies at the edge of ...

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

Standing Bear
1.1 / 5 (13) Jan 12, 2012
This is what I have felt all along. It was only a protestant fantasy that assumed earth centricism and uniqueness of life only here on this world. We will probably find out that life is also prevalent on many of these worlds. Bearing in mind the tiny fraction of time that we have been able to be self aware nothwithstanding communications abilities with regard to geological time not to mention universal time scales, the fraction of these worlds inhabited by people we can communicate with electronically or gravitationally or thru superspace could be quite small. However, there may be many more planets with cultures from earlier eras mirroring our own developement....savages, feudals, bronze agers, etc. We did nothing until we were bioengineered by aliens 13 thousand years ago in some lab here that we have yet to find but suspect it to be under the Persian Gulf, the Black Sea, or the Indian continental shelf last seen above water in the last ice age.
GreyLensman
4.9 / 5 (10) Jan 12, 2012
Poor Standing Bear, you sounded quite sensible until you went bioengineered wingnut. If there's one thing that a large number of planets underlines, it's that life has many opportunities to form naturally, requiring neither supernatural nor extraterrestrial assistance.
Crazy_council
1 / 5 (1) Jan 13, 2012
Standing bear ----

I think life will be the rule but inteligence is a different matter, if inteligence was an inevatability of biological evolution, we would have had clever dinos, crocks ect ect.

It quite concevable that baterial life is everyware but
we may be the only planet that had the right curcumstances at the right time for intelegence to appear, i hope not, but when you add up what we have learnt about evolution on our planet, i think intelect like ours, is probebly extreemly rare among life brearing planets.
Cave_Man
1 / 5 (1) Jan 16, 2012
Well if there were another earth out there it could not only harbor any portion of our earths history (similar at least).

so imagine a parallel earth where a large rock never wiped out the dinosaurs, what would that species look like now? would the chain of evolution which took place here happen on other earth like planets, what are the constraints on how similar it would have to be?

reptilian overlords at the center of the galaxy is sounding more and more plausible.