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Contact: Jane Platt (818) 354-0880
FOR IMMEDIATE RELEASEJune 1, 1999
ASTRONOMERS FIND SUN'S COOLEST NEIGHBORS
A pair of near-infrared telescopes sponsored by NASA and the
National Science Foundation has detected the coolest brown dwarfs
ever seen -- celestial objects that are neither fish nor fowl, or
in this case, neither planet nor star.
Brown dwarfs are often thought of as "stellar wannabes."
They are failed stars that never got hot enough to ignite the
nuclear fusion process that makes stars shine brightly. On the
other hand, they tend to be more massive than planets and do not
form around a star, as the planets in our solar system did.
"These latest discoveries are merging the fields of stellar
astronomy and planetary science," said Adam Burgasser, physics
graduate student at the California Institute of Technology,
Pasadena, CA. He is leading the hunt for these objects along
with Dr. Davy Kirkpatrick, senior staff scientist at the
JPL/Caltech Infrared Processing and Analysis Center.
After sorting through millions of celestial objects,
Burgasser discovered four brown dwarfs in images taken by a pair
of 1.3-meter (51-inch) telescopes near Tucson, AZ, and at Cerro
Tololo, Chile. The telescopes, used for the Two-Micron All Sky
Survey (2MASS), study near-infrared wavelengths that can't be
seen by the naked eye. They sense heat and thus detect heat-
emitting objects like stars and galaxies normally hidden by
curtains of cold dust. In this case, the brown dwarfs are too
cold to be seen in visible wavelengths, but 2MASS was able to
detect the small amounts of heat they emit.
Armed with this information, Michael Brown, Caltech
assistant professor of planetary astronomy, studied the objects
using the Keck Telescope atop Mauna Kea, HI, to look for the
presence of methane, a telltale chemical fingerprint of very cool
"Methane forms only in objects cooler than 900 degrees
Celsius (1,652 Fahrenheit)," Burgasser said. "That's only four
times hotter than the maximum setting on a conventional kitchen
"We think these brown dwarfs are only 30 light years away,"
said Kirkpatrick. "Because our telescopes can only see the
closest examples, this means the Milky Way must be brimming with
objects like these." The newly discovered brown dwarfs are
located in the constellations of Ursa Major (the Big Dipper),
Leo, Virgo, and Corvus.
The 2MASS telescopes are in the midst of a 3-1/2-year survey
of the entire sky. The survey is designed to catalog one million
galaxies, 300 million stars, and other celestial objects
throughout our Milky Way galaxy. The 2MASS telescopes actually
discovered five methane brown dwarfs, but one of them had been
found previously by the Sloan Digital Sky Survey, also supported
by NASA and the National Science Foundation.
The 2MASS project is based at the University of
Massachusetts, Amherst, where its principal investigator Dr.
Michael Skrutskie is a physics and astronomy professor. The
JPL/Caltech Infrared Processing and Analysis Center combines and
processes 2MASS images into usable data.
As part of NASA's Origins Program, 2MASS is funded by NASA's
Office of Space Science and the National Science Foundation.
Results from 2MASS will benefit future Origins missions,
including Space Infrared Telescope Facility and the Next
Generation Space Telescope. JPL manages the program for NASA's
Office of Space Science, Washington, DC. JPL is a division of
the California Institute of Technology, Pasadena, CA.
The current images, and additional 2MASS information and
images are available at: http://www.ipac.caltech.edu/2mass.
2MASS information and images are also available at: http://pegasus.phast.umass.edu.