Israeli-Swiss Researchers Make an Unusual Discovery - a Star Orbited by a Brown Dwarf'

Two Israeli researchers working in conjunction with a Swiss team have discovered an unusual planetary system outside the solar system.

The Swiss team has been searching the skies using telescopes in France and Chile while the Israeli researchers, Professor Tsevi Mazeh and Dr. Shay Zucker of Tel Aviv University, handled the data analysis. A preliminary analysis of the light coming from one of the stars the team had been investigating, known as HD41004, indicated that the star had a nearby planet which made a complete orbit approximately every 30 hours. But according to Zucker, this seemed very suspicious, since no planet discovered hitherto orbits its star that quickly.

The two Israelis therefore performed further analysis of the star's light, using a new technique that they had developed. "Using this technique, we discovered that in truth, there were two stars," Zucker said. "The smaller star is orbited by a body called a `brown dwarf' - a body that is similar to a star, and larger than an ordinary planet. It was this [body] that was completing a revolution every 30 hours."

Additional observations and analyses, however, revealed that this system also contained a real planet that orbited the larger star. This planet completes one revolution approximately every 600 days.

Though the first planets outside the solar system were discovered only some 10 years ago, today about 100 are known. The HD41004 system, however, is the first system ever discovered that contains a double star, a brown dwarf and a planet. The existence of such a system may indicate that the birth process of double stars, planets and brown dwarfs are more closely related than had previously been thought, Zucker said.