— Don YeoManS
Milky Way blows
cosmic bubbles
By Ron Cowen
The Milky Way is blowing bubbles of
cosmic proportions.
Twin bubbles of gamma ray–emitting
gas, each the size of a small galaxy, sit
above and below the center of the Milky
Way like the ends of a giant dumbbell,
astronomers have discovered.
Douglas Finkbeiner of the Harvard-Smithsonian Center for Astrophysics in
Cambridge, Mass., and colleagues analyzed data from NASA’s Fermi Gamma-ray Space Telescope to find the bubbles.
Finkbeiner described the findings,
which appear in the Dec. 1 Astrophysical
Journal, during a November 9 briefing.
The bubbles aren’t readily apparent
because a high-energy gamma-ray fog,
discovered by Finkbeiner and his col-
leagues last year, fills the sky, mainly
due to high-speed electrons and protons
interacting with light and interstellar
gas in the galaxy. But when Finkbeiner
and his colleagues subtracted the fog
from the Fermi telescope’s data, they
uncovered the two giant lobes.
Spacecraft encounters comet
Small but spunky, hyperactive Comet Hartley 2 is shaped like a peanut
and spews several jets of gas and dust from both its day and night sides,
NASA’s EpoXI spacecraft has revealed. Intriguingly, the activity of the comet
appears to be driven by the sudden venting into space of frozen carbon
dioxide— dry ice —rather than the frozen water that has been seen coming
off many other comets, said principal mission scientist mike A’Hearn of the
University of maryland in College park. It’s the emission of carbon dioxide,
rather than frozen water, that waxes and wanes most dramatically as the
active portions of the 2-kilometer-long comet rotate in and out of sunlight,
A’Hearn noted during a November 4 press briefing at NASA’s Jet propulsion
Laboratory in pasadena, Calif., just a few hours after EpoXI passed within
700 kilometers of the elongated object. As images from the encounter
arrived at the lab, JpL planetary scientist Don Yeomans commented: “this
is the type of moment that scientists live for.” — Ron Cowen
from top: GSfC/NASA; JpL/NASA, UmD
www.sciencenews.org
