Archive for November, 2010
This artist’s impression shows HIP 13044 b, an exoplanet orbiting a star that entered the Milky Way from another galaxy
Astronomers claim to have discovered the first planet originating from outside our galaxy.
The Jupiter-like planet, they say, is part of a solar system which once belonged to a dwarf galaxy.
This dwarf galaxy was in turn devoured by our own galaxy, the Milky Way, according to a team writing in the academic journal Science.
The star, called HIP 13044, is nearing the end of its life and is 2000 light years from Earth.
The discovery was made using a telescope in Chile.
Planet hunters have so far netted nearly 500 so-called “exoplanets” outside our Solar System using various astronomical techniques.
But all of those so far discovered, say the researchers, are indigenous to our own galaxy, the Milky Way.
This find is different, they say, because the planet circles a sun which belongs to a group of stars called the “Helmi stream” which are known to have once belonged to a separate dwarf galaxy.
This galaxy was gobbled up by the Milky Way between six and nine billion years ago in an act of intergalactic cannibalism.
The new planet is thought to have a minimum mass 1.25 times that of Jupiter and circles in close proximity to its parent star, with an orbit lasting just 16.2 days.
The exoplanet was detected by a team using the MPG/ESO 2.2-m telescope in Chile
It sits in the southern constellation of Fornax.
The planet would have been formed in the early era of its solar system, before the world was incorporated into our own galaxy, say the researchers.
“This discovery is very exciting,” said Rainer Klement of the Max Planck Institute for Astronomy in Heidelberg, Germany, who targetted the stars in the study.
“For the first time, astronomers have detected a planetary system in a stellar stream of extragalactic origin. This cosmic merger has brought an extragalactic planet within our reach.”
Dr Robert Massey of the UK’s Royal Astronomical Society said the paper provided the first “hard evidence” of a planet of extragalactic origin.
“There’s every reason to believe that planets are really quite widespread throughout the Universe, not just in our own galaxy, the Milky Way, but also in the thousands of millions of others there are,” he said, “but this is the first time we’ve got hard evidence of that.”
The new find might also offer us a glimpse of what the final days of our own Solar System may look like.
HIP 13044 is nearing its end. Having consumed all the hydrogen fuel in its core, it expanded massively into a “red giant” and might have eaten up smaller rocky planets like our own Earth in the process, before contracting.
The new Jupiter-like planet discovered appears to have survived the fireball, for the moment.
“This discovery is particularly intriguing when we consider the distant future of our own planetary system, as the Sun is also expected to become a red giant in about five billion years,” said Dr Johny Setiawan, who also works at the Max Planck Institute for Astronomy, and who led the study.
“The star is rotating relatively quickly,” he said. “One explanation is that HIP 13044 swallowed its inner planets during the red giant phase, which would make the star spin more quickly.”
The new planet was discovered using what is called the “radial velocity method” which involves detecting small wobbles in a star caused by a planet as it tugs on its sun.
These wobbles were picked up using a ground-based telescope at the European Southern Observatory’s La Silla facility in Chile.
By Neil Bowdler Science reporter, BBC News
In March 2009, NASA launched a spacecraft known as Kepler. This space observatory’s mission is to detect the presence of extrasolar planets (exoplanets), that is, planets located around stars outside of our solar system.
Artist’s conception of the Gliese 851 system
One of Kepler’s main objectives is to discover Earth-like planets- especially ones that exist in the so-called "Goldilocks zone," an area near a star in which water and air (the primary ingredients of life) can exist. To date, the Kepler mission team has released a list of over three hundred objects that are candidates for exoplanets and will release another list of four hundred candidates next February. How many of these objects are Earth-sized and exist in a Goldilocks zone remains to be seen.
Previously astronomers around the world had discovered over 400 exoplanets, but up to now, most are the size of or larger than Jupiter. In fact, most are much larger than Jupiter. And none have been located in a Goldilocks zone.
However, in April, scientists using the Hawaiian-based Keck Telescope announced they had discovered an Earth-sized planet at just the right distance from a star that would allow for air and liquid water. It has been designated Gliese 851g. 851g is about 50 percent larger than Earth and is 14 times closer to its star than the Earth is from our Sun. However, Gliese 851 is smaller and colder than our Sun, so the Goldilocks zone is much closer to Gliese 851 than it is in our solar system.
Gliese 851 is a type of star known as a red dwarf and has about one-third the mass of our Sun. It is located in the constellation of Libra, about 20 light years away. Astronomers believe that temperatures on Gliese 851g range from about 0 to 100 Â°F. Other planets have been discovered orbiting Gliese 851; one world is the size of Neptune and another seems to have a runaway greenhouse effect.
Currently, scientists do not have any technology capable of detecting life on other worlds, although such technology may someday exist.
Comparison of our Sun and Gliese 851
All images courtesy of NASA and Wikipedia. Â© 2010 Tessmann Planetarium, Santa Ana College.