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3\12 Virtual Observatory Prototype Produces Surprise Discovery
Part 1 of 2

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FOR IMMEDIATE RELEASE: March 12, 2003

Virtual Observatory Prototype Produces Surprise Discovery
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Early demo project identifies new brown dwarf
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A new approach to finding undiscovered objects buried in immense 
astronomical databases has produced an early and unexpected payoff: a 
new instance of a hard-to-find type of star known as a brown dwarf.

Scientists working to create the National Virtual Observatory (NVO), 
an online portal for astronomical research unifying dozens of large 
astronomical databases, confirmed discovery of the new brown dwarf 
recently. The star emerged from a computerized search of information
on millions of astronomical objects in two separate astronomical 
databases. Thanks to an NVO prototype, that search, formerly an 
endeavor requiring weeks or months of human attention, took 
approximately two minutes.

NVO researchers emphasized that a single new brown dwarf added to a 
list of approximately 200 known brown dwarfs isn't as scientifically 
exciting as the timing of the new discovery and the tantalizing hint 
it offers to the potential of NVO. The discovery came at a stage when 
organizers were simply hoping to use NVO to confirm existing science, 
not make new findings. 

"This was just supposed to be a feasibility demo. We just wanted it to 
find all the brown dwarfs that others could find, to show that this 
was a valid approach," said Alex Szalay, director of the NVO project 
and Alumni Centennial Professor of Astronomy in the Johns Hopkins
Krieger School of Arts and Sciences. "This was the first time we 
turned the NVO devices on, and they immediately yielded a new 
discovery from data that's been publicly available for at least a year 
and a half."

According to Szalay, that's just the kind of finding organizers are 
hoping will start pouring from the NVO in a few more years: 
revelations available in data already gathered by observatories, 
probes and surveys, but left undiscovered because new technology is 
pouring new data so rapidly into a variety of different databases.

The new discovery came from one of three scientific prototypes NVO 
scientists presented at the January 2003 meeting of the American 
Astronomical Society. NVO partners at the California Institute of 
Technology's Infrared Processing and Analysis Center (IPAC)
implemented the software for the prototype that found the new brown 
dwarf. Principal contributors to the demonstration project included 
Davy Kirkpatrick and Bruce Berriman, the demonstration project leader, 
both from IPAC.

Different astronomical surveys and probes look at the sky with 
instruments sensitive to different portions of the electromagnetic 
spectrum. Often, the specific part of the spectrum measured by a 
particular instrument can be the key to gaining insights to a
particular class of objects or certain properties of those objects. 
But some of the oddest characters in the cosmos, such as brown dwarfs, 
only really start to stick out from the enormous background of the
universe when looked at by different instruments that show how the 
objects appear at points across the electromagnetic spectrum.

Among the key ingredients NVO will provide for multiple database 
searches is a standard way of delivering data, according to NVO 
co-director Roy Williams, a senior scientist at Caltech.

"The brown dwarf emerged from looking at two independent surveys 
together, and it's the standard way of delivering the data from the 
surveys that enables them to be federated and us to find out what's in 
there," Williams said. "It's hard to identify the brown dwarfs in 
either survey, but if you put them together, they start to come out."

"People can do these kinds of investigations without NVO," said Bob 
Hanisch, a Space Telescope Science Institute astronomer and NVO 
project manager. "But with the NVO, they'll run much more rapidly and
effectively. Many projects that astronomers can't take on now because 
of the sheer volume of sifting and searching involved will suddenly 
become much more feasible." Astronomers and computer scientists from
17 research institutions are currently collaborating to build the 
framework for the NVO, which is funded by a five-year, $10 million 
Information Technology Research Grant from the National Science 
Foundation. 

For the brown dwarf project, researchers wanted to show that they 
could use NVO connections they had built between two large databases 
-- the Sloan Digital Sky Survey (SDSS) and the Two Micron All Sky
Survey (2MASS) -- to confirm brown dwarfs already identified through 
previous non-NVO comparison of those databases.

Brown dwarfs were, for many years, a missing link in astronomers' 
model of star formation. The first definitive detection of a brown 
dwarf didn't come until 1995, when a team at Johns Hopkins and Caltech
announced that they had firmly identified one. Brown dwarfs are hard 
to detect because they're small, cool stars, sometimes described as 
"failed stars," with less than 8 percent the mass of the sun. That's 
still hundreds of times the mass of the gas giant planet Jupiter, but 
not massive enough to create the self-sustaining nuclear reaction that 
powers larger stars. As a result, a brown dwarf grows cooler and 
dimmer as it ages, making it increasingly difficult for astronomers to 
detect.

To find the new brown dwarf and two already-recognized brown dwarfs, 
the NVO project searched through information on 15 million 
astronomical objects in SDSS and 160 million objects in 2MASS. The 
prototype found that in the region of sky currently covered by both 
surveys (about 0.4 percent of the night sky) the two databases had 
300,000 astronomical objects in common or very likely to be references 
to the same physical object.

Additional selection criteria based on the brightness differences of 
the objects between the SDSS and 2MASS catalogs suggested that the NVO 
prototype had found seven new brown dwarf candidates, but followup
observations and human analysis whittled that list down to three, 
yielding the confirmed brown dwarf and two more candidates that have 
yet to be spectroscopically verified. Szalay said that was a fine 
success rate, given the magnitude of the data searched.

"We narrowed it down from tens of million of objects, to a few hundred 
thousand, to a handful," Szalay explained. "This is truly remarkable."

"The discovery of the new brown dwarf is a wonderful example of what 
can be done with powerful tools to mine large databases," said Rich 
Kron, astronomer at Fermilab and the University of Chicago and an SDSS
spokesperson. "Correlating different maps of the sky greatly expands 
the 'discovery space' of each survey.  No doubt, many more remarkable 
objects still remain to be found."

"The combined, multi-wavelength view of the universe is definitely 
more than the sum of its parts," says Roc Cutri, 2MASS project 
scientist and IPAC deputy director. "The SDSS and 2MASS data sets are
unprecedented resources for astronomical discovery in their own right, 
but the synergy realized by combining these massive data sets opens 
research possibilities that were only dreamed of before."

(continued)

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