Distant star's radiation bursts puzzle scientists

JANUARY 22, 1992: A group of scientists reported that for the last several months, a star about 815 light years away in the constellation Auriga has begun emitting unusual bursts of electromagnetic radiation. The star, Yale #2143, is barely visible to the naked eye or binoculars in the southern sky near Capella, one of the brightest points in our night sky.

Yale 2143 contains about twice the mass of our solar system and astronomers have speculated in the past that it may be a variable star or a member of a binary system. "Otherwise, not much is known about it," said Robert Hartman of the Kitt Peak National Observatory in a telephone interview. "But this isn't normal behavior for a star at its point in its life-cycle so we're very interested in it."

Normally, a star like Yale 2143 burns white-hot at a temperature from 7,000 to 10,000 Kelvin and has a life-cycle of several billion years. "It's larger and hotter than our sun, but otherwise it's really not that exceptional as stars go," said Hartman.

So why all the excitement in the astrophysics community about this nearly invisible and apparently non-descript member of the heavens?

"Because, quite simply, nothing we've seen has done this before." The star suddenly began emitting strong irregular bursts of invisible radio and microwave radiation a few months ago that are unusually focused around a small number of wavelengths. Scientists first noticed the bursts when they interfered with data collection from quasars and other deep-sky objects. "At first we didn't know where it was coming from, and then we weren't sure if it was coming from this particular star or another phenomenon behind it," said Mailika Gibbons, the graduate assistant credited with first observing the bursts. "But it quickly became clear that this was a local event, happening right in our stellar backyard."

Scientists are still collecting data and analyzing the phenomenon. When asked to speculate about its cause, Dr. Hartman declined, but emphasized that this event might lead to significant revision of our understanding of a star's life-cycle. "The main sequence of a star is presently understood to be a rather uneventful period. This could reveal it to be a time when dynamic changes occur."