MessageToEagle.com - Billions of stars in our galaxy have captured nomad, alien worlds that once roamed interstellar space.
The nomad worlds, which were kicked out of the star systems in which they formed, occasionally find a new home with a different sun.
New research gives possible explanation of the existence of some planets that orbit surprisingly far from their stars, and even
the existence of a double-planet system.
"Stars trade planets just like baseball teams trade players," said Hagai Perets of the Harvard-Smithsonian Center for Astrophysics, who along with
Thijs Kouwenhoven of Peking University, China, presents a paper on the subject in the April 20th issue of The Astrophysical Journal.
To reach their conclusion, Perets and Kouwenhoven simulated young star clusters containing free-floating planets.
They found that if the number of rogue planets equaled the number of stars, then 3 to 6 percent of the stars would grab a planet over time.
The more massive a star, the more likely it is to snag a planet drifting by.
They studied young star clusters because capture is more likely when stars and free-floating planets are crowded together in a small space.
Over time, the clusters disperse due to close interactions between their stars, so any planet-star encounters have to happen early
in the cluster's history.
Rogue planets are a natural consequence of star formation. Newborn star systems often contain multiple planets. If two planets interact,
one can be ejected and become an interstellar traveler. If it later encounters a different star moving in the same direction at the same speed,
it can hitch a ride.
Every star in the galaxy has at least one planet, but that is leaving aside the potentially billions more planets
that were ejected from their solar system and are now hurtling through the universe all alone.
A captured planet tends to end up hundreds or thousands of times farther from its star than Earth is from the Sun. It's also likely to have
a orbit that's tilted relative to any native planets, and may even revolve around its star backward.
Astronomers haven't detected any clear-cut cases of captured planets yet. Imposters can be difficult to rule out. Gravitational
interactions within a planetary system can throw a planet into a wide, tilted orbit that mimics the signature of a captured world.
Finding a planet in a distant orbit around a low-mass star would be a good sign of capture, because the star's disk wouldn't have
had enough material to form the planet so far out.
A captured world drifts at the outer edge of a distant star system, so far from its Sun-like host that the star's disk is
barely resolvable at upper right. New research shows that one in 20 stars within our galaxy might have captured a free-floating planet
The best evidence to date in support of planetary capture comes from the European Southern Observatory, which announced in 2006
the discovery of two planets (weighing 14 and 7 times Jupiter) orbiting each other without a star.
"The rogue double-planet system is the closest thing we have to a 'smoking gun' right now," said Perets.
"To get more proof, we'll have to build up statistics by studying a lot of planetary systems."
Could our solar system harbor an alien world far beyond Pluto? Astronomers have looked, and haven't found anything yet.
"There's no evidence that the Sun captured a planet," said Perets. "We can rule out large planets. But there's a non-zero chance that
a small world might lurk on the fringes of our solar system."
Spectacular Sombrero Galaxy
Captured By Chandra/Hubble/Spitzer
It resembles a shining UFO or a wide-brimmed hat, but this isn't what it looks like.
One of most famous spiral galaxies (Messier 104) is also widely known as the "Sombrero" (the Mexican hat) because of its particular shape.
The galaxy's impressive, unusually large and extended central bulge and its lane of dark interstellar dust give the galaxy its unusual resemblance.
Invader From Another Galaxy
This alien intruder from another galaxy is in many ways different from other exoplanets observed by astronomers.
Located about 2000 light-years from Earth in the southern constellation
of Fornax (the Furnace), the Jupiter-like planet orbits a dying star of extragalactic origin and risks to be engulfed by it.
Alien Species Living In The Inner Milky Way Could Be In Danger
Few people doubt there is intelligent alien life in the Milky Way galaxy, but where can we expect to find it?
Astronomers think that while the inner sector of the MIlky Way Galaxy may be the most likely to support habitable worlds.
Unfortunately some of these places are also most dangerous to all life-forms.
Warp-Speed Planets Are Some Of The Fastest Objects In The Milky Way
Warped planets are some of the fastest objects in the Milky Way and they zoom through space near the speed of light.
Some years ago astronomers were astonished when they they found the first runaway star flying out of our Galaxy at a speed of 1.5 million miles per hour.
The discovery intrigued theorists, who wondered: If a star can get tossed outward at such an extreme velocity, could the same thing happen to planets?
Living Earth Simulator - Supercomputer Predicting The Future
In Douglas Adams book the Hitchhikers Guide to the Galaxy we encounter a machine called Deep Thought. It is the most powerful computer ever built. Deep Thought is capable of answering questions
concerning life, the Universe, and simply everything. Now scientists are planning to create a similar machine. It is called the Living Earth Simulator (LES).
Cosmic Robbers: Black Hole Jets May Cause
Galaxy NGC 3801 To Die And Lose Its Stars
Armchair explorers of the cosmos can now have at their fingertips the nearly 2,000 distant planetary systems discovered by NASA's Kepler Mission.
Now available for free from the iTunes App Store, Kepler Explorer was developed through the OpenLab initiative at UC Santa Cruz,
which brought together faculty and students in astrophysics, art, and technology for a summer institute last year.
A Merger Of Galaxy Clusters About 5.2 Billion Light Years From Earth
A violent collision between two galaxy clusters in which so-called normal matter has been wrenched apart from dark matter through a
violent collision between two galaxy clusters.
Astronomers have observed this cosmic event using a combination of powerful observatories in space and on the ground.
Galaxy With A Voracious Appetite
Observations by the two of the European Space Agency's space observatories have provided a multi-wavelength view of
the mysterious galaxy Centaurus A.
The new images, from the Herschel Space Observatory and the XMM-Newton x-ray satellite, are revealing further hints about
its cannibalistic past and energetic processes going on in its core.
Though the universe is filled with billions upon billions of stars, the discovery of a single variable star in 1923 altered the
course of modern astronomy. And, at least one famous astronomer of the time lamented that the discovery had shattered his world view.