Tamara Traubman
Astronomers have discovered a new planet orbiting a star called Epsilon Eridani which is not far from the solar system. According to Prof. Jeff Marcy, an astronomer from the University of California at Berkeley and a partner in the research, "the discovery could help find out if the Earth, with all the variety of life forms on it, is a unique jewel in the universe or something common."
On Friday, Prof. Mercy and his colleagues presented their findings at the General Assembly of the International Astronomical Union in Manchester, UK. "The star Epsilon Eridani is only ten light-years away from us," Marcy said at the meeting. "This is a very exciting discovery. In a hundred or two hundred years, this could be one of the first planets that humanity will visit."
The team discovered the planet by observing the oscillations of the star Epsilon Eridani affected by the gravitational pull of the planet orbiting it. According to these fluctuations - an aid used by astronomers in their search for new planets - the researchers calculated the mass of the planet and its distance from the star. They discovered that the mass of the new planet is very similar to the mass of Jupiter, the largest planet in the solar system. They also discovered that for seven years the planet completes its orbit around Epsilon Eridani.
Another team - which studied Epsilon Eridani with the help of a telescope on Mount Mauna Kaa in Hawaii - noticed about two years ago a ring of dust around the star that is "amazingly similar", according to one of the researchers, Prof. Benjamin Zuckerman from the University of California, Los Angeles, to the Kuiper belt - the belt of comets at the edge our solar system. He and his colleagues then even noticed a bright area and predicted that it was a planet orbiting the star.
"This system is very similar to ours," Zuckerman said. "If we could see what our solar system looked like about four billion years ago, it must have been pretty similar to what Epsilon Eridani looks like today. The consequences are that if there is one system similar to ours on a star so close, it can be assumed that there are many others as well."
Epsilon Eridani was also one of the first places to which the famous astronomer Frank Drake pointed a radio telescope in search of alien civilizations in the late 50s. "What Drake did not know then," Zuckerman explains, "is that Epsilon Eridani is too young for intelligent life to develop on the planets around it. He is even too young for a primitive life to develop in him."
Either way, the planet orbiting Epsilon Eridani does not seem like a good candidate for life to grow on it. This is because its large mass causes gravitational conditions too strong for the existence of life.
In recent years, astronomers have been conducting an intensive pursuit to identify new planets outside the solar system. Of the forty planets discovered in the last decade, most of them have a mass similar to that of Jupiter or greater than it. The smaller and farther the planet is from its parent star, the harder it is to detect. Therefore, although astronomers are also interested in discovering smaller planets, they are difficult to detect with existing methods.
However, a team led by Marcy announced about two months ago that they had discovered the two smallest planets discovered so far. One revolved around the star Ceti@79 and the other around the star HD@46375. Both have a mass similar to that of Saturn, that is, less than a third of that of Jupiter.
