An international team of astronomers has released to
the public the first data collected as part of the Radial
Velocity Experiment, an ambitious spectroscopic survey
aimed at measuring the speed, temperature, surface gravity
and composition of up to a million stars passing near the
The measurements, released Feb. 10 at an astrophysics
workshop at the Aspen Center for Physics in Colorado and
available online to other astronomers, includes examination
of old "fossil" stars that were born when our Milky Way
galaxy was in its infancy. Team members posit that such
data may eventually provide evidence to back up theories
that our galaxy has, over time, "cannibalized" other,
smaller galaxies and is "digesting" them.
"Our research focuses on the oldest stars and probes
the earliest phases of the evolution of our home galaxy,
the Milky Way," said RAVE team member Rosemary Wyse, a
professor in the Krieger School's
Henry A. Rowland
Department of Physics and Astronomy at Johns Hopkins.
"The unprecedented sample available with RAVE will allow me
— and now, with the release of this data, others
— to test ideas of our origins laid out by various
The team members are from the United States, Germany,
Australia, Canada, the Netherlands, the United Kingdom,
Slovenia, Italy, Switzerland and France.
The survey has been made possible by the unique
capabilities of the "six-degree field" multi-object
spectrograph on the 1.2-meter UK Schmidt Telescope of the
Anglo-Australian Observatory, located at Siding Spring
Observatory in New South Wales, Australia. This instrument
is capable of obtaining spectroscopic information for as
many as 150 stars at once, from an area of the sky equal to
more than 150 times the area covered by the full moon.
"The data we are making public today is twice the
sample size of any previous survey, and has extremely high
quality," Wyse said. "Other astronomers can definitely use
these data in their work. All they have to do is go to our
Web site [www.rave-survey.org]
and download it."
The RAVE survey measures the velocities of stars along
the line of sight, something that has previously been
difficult to obtain for such large samples of stars. Data
from RAVE's first year of operation consists of information
from some 25,000 stars, including measurement of their
brightness, color and motion across the sky.
"This data set will provide a unique resource for all
astronomers working in the field of galactic evolution and,
with our public data release, the astronomical community
can participate in our endeavor," said Tomaz Zwitter of the
Ljubljana University in Slovenia and project scientist of
the RAVE survey. "This first sample by itself is already
two times the size of the previous largest survey of stars
near the sun."
Matthias Steinmetz, director of the Astrophysical
Institute Potsdam and leader of the RAVE collaboration,
predicted that "the full RAVE survey will provide a vast
resource of stellar motions and chemical abundances,
allowing us to answer fundamental questions of the
formation and evolution of our galaxy."
Funding for RAVE is provided for Johns Hopkins by the
National Science Foundation and for other team members by
the national research councils of their countries, as well
as by private sources.