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The Laboratory
in the News

Carbon dioxide release threatens oceans
Livermore researchers have found that continued release of carbon dioxide (CO2) during the next several centuries would make the oceans more acidic than they have been during the past 300 million years, resulting in damage to marine life.
The burning of coal, oil, and gasoline releases CO2 into the atmosphere. Since the Industrial Revolution, CO2 emissions have contributed to global climate change, notable by an increase in overall temperatures worldwide. Eventually, the ocean absorbs most of the CO2.
This absorption has been viewed as beneficial because it removed greenhouse gases from the atmosphere. However, recent research by Livermore scientists Kenneth Caldeira and Michael Wickett shows that continued CO2 emission to the atmosphere from the burning of fossil fuel may make the oceans more acidic than they have been for millions of years, except following extreme events in Earth’s remote past such as when the dinosaurs became extinct.
Caldeira and Wickett’s results appear in “Anthropogenic CO2 and Ocean pH” in the September 25, 2003, issue of Nature.
Their work complements other carbon cycle research at Livermore sponsored by the Department of Energy’s Office of Biological and Environmental Research. These investigations include experiments to understand how ocean acidity can be neutralized; studies of the interactions between the carbon cycle and climate, leading to a more systematic evaluation of climate models; and research on ways of storing CO2 underground so that it does not contaminate the atmosphere or the oceans.
Contact: Kenneth Caldeira (925) 423-4191 (caldeira2@llnl.gov).

Milky Way and neighboring galaxy formed in similar way
Astronomer Kem Cook of Livermore’s Institute of Geophysics and Planetary Physics and a collaboration of international researchers from South America, Australia, and Europe have discovered that a neighboring galaxy—the Large Magellanic Cloud (LMC)—and the Milky Way galaxy have similar early formation histories. The LMC is 160,000 light years away from our larger and more regular galaxy.
In their research, Cook and his collaborators identified a spherical halo in the LMC made of the oldest and most metal-poor stars moving like atoms in a hot gas. That halo is similar to a spherical halo in the Milky Way. They made this discovery by measuring the movement of 43 RR Lyrae stars in the inner regions of the LMC. RR Lyrae stars, which are found in both the Milky Way and the LMC, are excellent tracers of old, metal-poor star populations. The presence of spherical halos in both galaxies suggests that they had similar early formation scenarios: extended hierarchical accretion and rapid collapse.
Models of halo formation by accretion indicate that the old, metal-poor stars formed in small satellite galaxies, which were subsequently eaten up by the Milky Way. Models of halo formation by dissipational collapse indicate that the halo formed rapidly before the disk collapsed. When Cook and his collaborators applied these models to smaller galaxies such as the LMC, they found a halo was formed and populated by the LMC’s oldest objects.
Results from their research are featured in the September 12, 2003, issue of Science, in an article titled “Kinematic Evidence for an Old Stellar Halo in the Large Magellanic Cloud.”
Contact: Kem Cook (925) 423-4634 (cook12@llnl.gov).

A sharper view of the universe
A major milestone in astronomical history took place on September 20, 2003, at the W. M. Keck Observatory on Mauna Kea, Hawaii. That night, scientists used a laser to create an artificial guide star on the Keck II 10-meter telescope, which allowed them to correct the blurring of a star with the telescope’s adaptive optics systems. Laser guide stars have been used on smaller telescopes, but this is the first successful use on the current generation of large telescopes.
Installed in 1999, the Keck adaptive optics system allows astronomers to minimize the blurring effects of Earth’s atmosphere, producing images with unprecedented detail and resolution. The system uses light from a relatively bright star to measure the atmospheric distortions and then correct for them, but only about 1 percent of the sky contains stars sufficiently bright to be of use. By using a laser to create a virtual star, astronomers can study much fainter objects, increasing coverage to more than 80 percent of the objects in the sky.
On September 20, the system locked on a 15th magnitude star—a member of a T Tauri binary called HK Tau—and revealed details of the circumstellar disk of the companion star. Throughout the evening, the laser guide star held steady and bright, shining at a magnitude of about 9.5. Although that magnitude is 25 times fainter than what the human eye can see, it is ideal for the Keck adaptive optics system to measure and correct for atmospheric distortions.
Contact: Deanna Pennington (925) 423-9234 (pennington1@llnl.gov).

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UCRL-52000-03-12 | December 3, 2003