Little, rocky planets can coalesce around a wide variety of stars, suggesting that Earth-like alien worlds may have formed early and often throughout our Milky Way galaxy’s history, a new study reveals.
Astronomers had previously noticed that massive, Jupiter-like exoplanets tend to be identified around stars with high concentrations of so-called “metals” — elements heavier than hydrogen and helium. But smaller, terrestrial alien planets show no such loyalty to metal-wealthy stars, the new study found.
” Modest planets could be widespread in our galaxy, since they do not require a high content material of heavy components to form,” stated study lead author Lars Buchhave of the University of Copenhagen in Denmark. Buchhave and his colleagues analyzed data from NASA’s planet-hunting Kepler space telescope, which has been continuously observing much more than 150,000 stars since its launch in March 2009.
Kepler watches these stars for tiny brightness dips, some of which are triggered by alien planets that cross the stars’ faces from the telescope’s point of view. To date, Kepler has flagged far more than 2,300 exoplanet candidates. Whilst just a little fraction have been confirmed, Kepler scientists estimate that at least 80 percent will finish up being the actual deal. [ Gallery: A Globe of Kepler Planets ]
In the new study, the researchers looked at Kepler observations of 226 planet candidates circling 152 different stars. A lot more than three-quarters of these potential planets are smaller than Neptune — i.e., their diameters are less than four times that of Earth — and some of them are as diminutive as our own planet, researchers mentioned.
The astronomers studied the stars’ spectra and identified that modest, rocky worlds circle stars with a a lot broader range of metal content material than do giant planets.
“Naively, one may think that the much more material you have in the (protoplanetary) disk, the a lot more probably you are to form (small) planets,” Buchhave told Space.com via e-mail. “What we see, though, is that little planets form about stars with a wide range in heavy element content, even though the close-in Jupiter -kind planets appear to predominantly form around stars with a higher metal content.”
In reality, little, terrestrial planets can form around stars almost four times far more metal-poor than our personal sun, researchers mentioned. The final results recommend that Earth-size worlds may be common all through the Milky Way, maybe offering numerous places for life to gain a foothold.
“Since modest planets could be widespread in our galaxy, the probabilities of life creating could be larger, simply due to the fact there could be more terrestrial-sized planets exactly where life could evolve,” Buchhave said.
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Alien Earths May Be Widespread in Our Milky Way Galaxy by Mike Wall, SPACE.com Senior Writer Date: 13 June 2012 Time: 01:01 PM ET FOLLOW US SHARE An artist conception of a newly formed star surrounded by a swirling protoplanetary disk of dust and gas, where debris coalesces to create rocky ‘planetesimals’ that collide and grow to eventually form…