On the horizon
In the hunt for the universe's first stars, some astronomers are looking no farther than their galactic backyard.
A team led by Anna Frebel of the Australian National University in Canberra has discovered a star in the Milky Way's halo that appears to be among the oldest yet observed. The discovery is boosting astronomers' confidence that they will be able to find and study the earliest stars, which formed a few hundred million years after the Big Bang. The discovery appears in today's edition of the journal Nature.
The star's age is inferred from its lack of metal. Metals and other heavy elements are forged in stellar furnaces. Stars shed this material at the end of their lives. Each generation of stars grows progressively metal rich, because the medium it springs from has been enriched by previous generations. Thus, the earliest stars would be virtually metal free.
The team's discovery, known as HE1327-2326, contains 300,000 times less iron than the sun, which is some 5 billion years old. This ranks HE1327-2326 as the most metal-starved star yet observed.
For the want of some sharks, the reef was lost. At least that's the conclusion of a team of Spanish and American marine scientists. The team built a detailed model of a typical Caribbean-reef food web - involving 250 species over 386 square miles and to a depth of 328 feet. The food web involved some 3,000 links among the species.
Among the results from the model: Overfishing of sharks appears to trigger a cascade of changes that undercuts the health of the reef itself. The team found that without sharks to feed on them, grouper populations grew. Groupers fed on the "grazers" such as parrotfish, which keep algae levels down. Combined with other human-induced changes to the reef, such as higher nutrient levels from land runoff, the undersea "weeds" won.
"It appears that ecosystems such as Caribbean coral reefs need sharks to ensure the stability of the entire system," says Enric Sala, deputy director of the Center for Marine Biodiversity and Conservation at the Scripps Institution of Oceanography in La Jolla, Calif., one of the participants in the study. The work appears in the April 12 issue of the Proceedings of the National Academy of Science.
Japan is reportedly set to expand its annual whale hunt to take two new species as well as nearly doubling its planned catch of minke whales. Under a new plan for what Tokyo calls its research whaling program, Japan would take humpback whales and fin whales in addition to the four species it currently hunts, sources close to the situation were quoted as telling Kyodo news agency.
The plan is to be submitted to the annual meeting of the International Whaling Commission (IWC) this summer. It calls for Japan initially to hunt about 10 humpbacks and 10 fin whales per year, Kyodo said, and to sharply increase the number of minkes it takes each year from the 440 it took in the Antarctic in the past whaling season.
Japan says it supports protection of endangered species but argues that others, such as the minke, are numerous enough to be hunted within limits.
Norway is the only country that hunts whales for profit. Iceland, like Japan, kills them for research in hunts sanctioned by the IWC. The US and other nations opposed to whaling say there is no scientific basis for the research.
Russian and French space officials signed a $448 million deal Monday to build a South American launchpad to send Russian rockets into space.
The deal includes terms for cooperation in planned launches of Russian Soyuz rockets from France's Kourou launchpad in French Guyana, starting in 2008.
Russia has pushed for access to Kourou because its proximity to the equator would allow Russian rockets to carry heavier cargoes to higher orbits.
Russia currently launches manned rockets from a launch pad in the Central Asian country of Kazakhstan.