A satellite carrying an infrared telescope has discovered swarms of large particles around the star Vega, and scientists say they think the particles and the star make up a complete solar system like our sun and the nine planets and thousands of asteroids and meteorites that surround it.
If true, it is the first evidence that the universe contains a second solar system like this one.
Though scientists have speculated for years that the Earth and its eight sister planets are not alone in the cosmos, they have never had evidence that their speculations were correct.
"The discovery provides the first direct evidence that solid objects of substantial size exist around a star other than the sun," said a statement yesterday from the Jet Propulsion Laboratory in Pasadena, where the Infrared Astronomical Satellite (IRAS) pictures are analyzed.
"The material could be a solar system at a different stage of development than our own," the statement said. Vega is a young star only 1 billion years old. The Earth's sun is almost 5 billion years old.
Nevertheless, Vega is similar to the sun. Its surface temperature has been measured at 10,000 degrees, almost the same as the sun. This suggests that though it is younger, Vega and its surrounding system may be undergoing the same kind of evolution that this solar system went through 4 billion years ago. Among the bodies in evolution around Vega could be even the equivalent of a young Earth.
What the IRAS satellite has seen time after time since it left the Earth last January is that Vega has appeared "much brighter and larger in infrared light" than any other similar star the satellite has observed, strongly suggesting there were celestial bodies in orbit around Vega just as the planets in this solar system circle the sun.
Further investigation showed that the bodies orbiting Vega had temperatures measured by the infrared telescope at about 300 degrees below zero Fahrenheit. This is far above the temperature of empty interstellar space and approximates the temperature of the inner rings of Saturn.
The telescope on IRAS has no way of counting the number of bodies in orbit around Vega or even of estimating their size. But the statement released yesterday by JPL said the particles could range "from buckshot to the size of asteroids and planets."
The statement said the material the telescope sees around Vega "could be comparable in mass to all the nine planets and other matter in our solar system, excluding our sun."
While the telescope is sensitive to heat, it cannot resolve, or "see," the mass of particles around Vega precisely enough to distinguish between them. All it sees is a ring of particles, not individual bodies. The buckshot-sized particles mentioned by JPL refer to small particles that may be in orbit around larger bodies, just as meteor showers and comets are in the Earth's orbit.
The telescope "sees" solid bodies circling Vega out to a distance of more than 7 billion miles, almost the distance from the sun to the most outer planets in this solar system. The third brightest star in the sky and the brightest star in the Constellation Lyra, Vega also is fairly close to this solar system, lying only 26 light years from Earth, or 156 trillion miles.
IRAS scientists H. H. Aumann of JPL and Fred Gillett of Kitt Peak National Observatory in Arizona said the bodies circling Vega must be larger than cosmic dust grains "because such small particles would already have gravitationally been drawn back into the star, leaving only intermediate and large-scale debris in orbit around Vega."
Interestingly, scientists chose to point the IRAS telescope more frequently at Vega than any other star because it shines with the right brightness to calibrate the instrument.
The discovery that Vega may support a planetary system is a bonus of the decision to use the star the way a ship's navigator might use the north star Polaris to guide him across the seas.