More than three dozen elusive whitedwarf stars have been found in a halo of objects surrounding our galaxy,marking the first direct evidence for previously unseen "darkmatter" and lending support to a widely held theory that there is muchmore to the universe than meets the eye.

The landmark finding, derived froma menagerie of data that had been lying around for between six and 30 years,accounts for at least 3 percent of the suspected dark matter in our galaxy,and possibly as much as 35 percent.

It is the first tantalizing piece ofa puzzle that physicists and cosmologistshave been trying to put together for seven decades.

The 38 old and dead white dwarfs foundin the study are the remains of the earliest stars that formed when ourgalaxy was young. It's akin to finding a cemetery loaded with billionsof corpses of people who all died after reaching age 100, then having tofold that thinking into what we thought we knew about human evolution.

And while the result shows that somefraction of supposedly mysterious dark matter is not really dark at all,nor even mysterious, it may shake up what we know about the formation andevolutions of stars and galaxies, several leading experts told SPACE.com.

"If it is correct then it is a fantasticallyimportant result," said Kim Griest, a physicist at University of California,San Diego.

Griest has worked since the mid 1990son the MACHO project, which uses a technique called microlensing to inferthe presence of unseen objects by noting how more distant light is bentas it travels past the hidden object. The group predicted last year thatthese white dwarfs, or something like them, existed.

The newly found white dwarfs providea natural explanation for the microlensing results, according to Ben R.Oppenheimer of the University of California, Berkeley, and his colleagues,who discuss their discovery in the March 23 issue of the journal Science.

If true, "then there are likely moreof these white dwarfs than there are all other stars in theMilky Way combined," Griest said. He added that "current theories can'tcope" with such a finding and it would "trigger a revolution" in ideasabout how galaxies and stars form and evolve.

"I would characterize [the study] asgroundbreaking," said Brad Hansen, a Princeton researcher who specializesin white dwarfs but was not involved in the new research. "There have beenhints and speculations before," he said, but this result confirms thatthere are a significant number of white dwarfs in the galactic halo.

Missing mass

Just as the invisible wind can be inferredby a dancing leaf, dark matter is assumed to exist based on how stars andgalaxies behave.

In the 1930s, astronomer Fritz Zwickynoted that distant clusters of galaxies did not contain enough stars toaccount for their swift movement. Other scientists found that thegravity generated by observed matter -- mostly stars -- is not enough tokeep individual galaxies and clusters of galaxies from simply flying apart.Resulting calculations showed that 90 to 95 percent of the mass in theuniverse is unaccounted for.

So theorists were forced to concludethat there is some sort of invisible or hard-to-see stuff out there, whichthey dubbed dark matter.

The new discovery confirms the existenceof one kind of dark matter, called normal or baryonic dark matter. Thehunt is still on for a more exotic type of dark matter, called nonbaryonic,assumed to be made of strange particles that behave in ways not entirelyknown.

Not really dark

White dwarfs are the dying embers thatrepresent the end of the line for roughly 94 percent of all stars. (Ourown Sun, now middle-aged at about 4.5 billion years old, will one day expandinto a red giant, shed much of its outer self into space, and then shrivelinto a white dwarf. The expulsion of material generates new stars.)

White dwarfs have collapsed into adense sphere that can be as small as Earth, and their masses average abouthalf that of the Sun.They are cool compared to younger stars, and so they are very dim.

But they are not completely dark.

Most researchers have expected formany years that at least part of what is termed dark matter would in factbe visible, though faint. Looking at it this way, dark matter is all aroundus, said Oppenheimer, the lead author of the study, in a telephone interview."You as a human being are in a sense dark matter, although in the infraredyou would look like a hundred-watt light bulb."

Oppenheimer and others agree that theterm "dark matter" can now seem confusing when used to describe the visibleremains of a star.

Next page: Challenging ideas aboutstar formation