عدد المساهمات : 38337
تاريخ التسجيل : 21/09/2009
|موضوع: At 11.2 billion years old, oldest planetary system discovered by astronomers الجمعة 30 يناير 2015, 04:23|| |
| Jan. 29, 2015|
- اقتباس :
At 11.2 billion years old, oldest planetary system discovered by astronomers
The prehistoric star is considered cool and small when compared to our Sun. The figure only has about 75 percent of Earth's mass
LOS ANGELES, CA (Catholic Online): The prehistoric star is considered cool and small when compared to our Sun. The figure only has about 75 percent of Earth's mass and is positioned just over 115 light years from Earth, inside the Milky Way Galaxy.
The five planets that are orbiting around it are somewhat smaller than Earth, believed to be between the sizes of Mercury and Venus. All five rotate swiftly around their host star and make complete orbits in less than 10 days. Astronomers think they each are probably rocky, due to their size.
It was not until three years ago that scientists knew planets could form around such primordial stars. The origins of Kepler 444 are thought to have been during an early era of the universe.
Astronomers had been previously uncertain if stony planets would have been able to form such a long period ago. This would have occurred when the universe was five times younger than the age it is now.
The discovery also proposes that there could have been ancient life in the universe and that it is much more likely than has ever been believed before. Astronomer Dr. Sarbani Basu, at Yale explains that the find suggests that the planets were possibly like Earth. They exist in a habitable zone, meaning there could have been ancient life there as well.
It was not until three years ago that scientists knew planets could form around such primordial stars. The origins of Kepler 444 are thought to have been during an early era of the universe, when elements that were heavier than helium and hydrogen were much scarcer than they were when the Sun was formed 4.6 billion years ago.
Basu says that when the Big Bang created only helium and hydrogen and all other elements, what scientists call "metals," were formed inside of stars. She added that with each generation, metals in the universe increase. The detail alone that Kepler 444 is a low metal star just helps to reinforce that it is a very old one.
Since heavy metals such as iron are considered the building blocks of rocky planets, astronomers originally thought that planetary systems would be uncommon around ancient stars.
"The discovered system does not have only 1 planet but 5 of them," Dr. Tiago Campante says. Campante works as a researcher at a university in the United Kingdom and is also one of the lead authors of the paper.
Campante declared that in order to understand the planetary system, astronomers had to first try to understand the host star. Astronomers must rely on information taken by NASA's Kepler spacecraft, which took images of the star one time a minute for four years, observing small variations in the brightness of the star.
Kepler 444 is believed to have come from the first generation of stars, so this planetary system tells astronomers that planets were forming around stars approximately 7 billion years before the Earth's own solar system.