starship-design: Mysterious light leaves astronomers in the dark

["L. Parker" <lparker@cacaphony.net>]

Mysterious light leaves astronomers in the dark

BY JOHN NOBLE WILFORD
New York Times

Every night at their telescopes, astronomers invite the universe to a battle
of wits. Surprise us, they say, with some teasing wink of light, some few
cryptic clues to something unfamiliar and, better yet, an implied challenge
to a cherished theory. In most cases, astronomers boast, we will have it
figured out by dawn.

Now astronomers have an unyielding mystery on their hands, something they
have observed and pondered for three years, a point of light deep in the
northern sky that appears to be like nothing seen before.

This may turn out to be only a curiosity, an odd variation of a familiar
phenomenon, or it may be the first evidence of some unsuspected object with
reverberating theoretical implications -- similar in that sense to the
recent detection of planets around other stars.


No clues from spectrum

The mystery object has so far confounded astronomers because they cannot
decipher the language of its light. Usually, by breaking down the spectrum
of light into its component elements and charting the spikes and dips on a
graph, astronomers can identify and describe an object within minutes.

In this case, however, astronomers are finding nothing familiar about the
light spectrum, a couple of Everests representing emissions from the object
surrounded by lower peaks and broad valleys of heavy elements that blot out
the true contours of the object's nature. They are beginning to sympathize
with archaeologists who sought to read Egyptian hieroglyphics without the
Rosetta Stone.

``I've never seen a spectrum anything like this, and I take spectra for a
living,'' said S. George Djorgovski, an astronomer at the California
Institute of Technology who is the leader of the sky survey that detected
the mystery object.

Whatever the astronomers are seeing, it is probably not a star, at least not
any normal star. The light signature of stars is much simpler than this
object's. Nor is it a distant galaxy, which would have much different light
patterns.

With little evidence and even less conviction, some astronomers speculate
that the object is a quasar, one of the sources of tremendous energies at
the farthest reaches of the universe where the enormous gravitational power
of black holes presumably gobbles up surrounding matter. If it is a quasar,
it must be a rare kind beyond current understanding.

``It doesn't look like a quasar to my eye, but I may be wrong,'' said
Wallace Sargent, a Caltech astronomer and quasar specialist, who is also
director of the Palomar Observatory in Southern California, where the
discovery was made.
So if it is not a normal star, galaxy or strange quasar, astronomers say,
the most intriguing possibility is that the mystery object is announcing the
existence of an entirely new cosmic phenomenon.

``But we must do everything to rule out the known before we postulate that
we have discovered something really and truly new,'' Djorgovski said.


New discoveries ahead

Mystification is likely to be a more common experience in astronomy as more
powerful telescopes and instruments with improved sensitivity are used for
systematic probes deeper into the universe and over broader stretches of
sky.
Several comprehensive sky surveys under way or just beginning are expected
to discover many rare or even previously unknown types of astronomical
objects and forces.
Exploring the entire northern sky in different color filters, for example,
the Digital Palomar Sky Survey, now nearing completion, has collected data
on more than 50 million galaxies and about 2 billion stars. The census has
identified more than 70 quasars at such great distances that they are being
seen at a time when the universe was less than 10 percent of its present
age.

One surprising discovery was a star like light several hundred times
brighter than the galaxy with which it was associated. Astronomers are not
sure, but they suspect they were seeing the after-effects of a gamma-ray
burst, the most powerful events in the universe today.
First detected in the 1960s, gamma-ray bursts are examples of an
astronomical mystery that is only now being solved.


Isolating rare points

For the survey, astronomers devised computer programs to sift through
processed photographs for star like objects, then distinguish the stars from
galaxies and isolate rare points of light that are not immediately
recognizable. This was how the new mystery object showed up.

Djorgovski and his team examined the object's light spectrum. Some of the
lines of emissions, especially the two Everest spikes, looked too sharp to
be from a quasar. They combed the star catalogs and published research
papers, but found nothing like it.

A search in the archives of X-ray and infrared surveys failed to show
anything in those wavelengths at the location where the object's visible
light was detected.

``This was the first one of something new, and a complete mystery to us,''
Djorgovski said.