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发布时间: 2025-05-31 00:00:43北京青年报社官方账号
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WASHINGTON, Aug. 31 (Xinhua) -- Astronomers using NASA's Chandra X-ray Observatory discovered the first pair of supermassive black holes in a spiral galaxy similar to the Milky Way, NASA announced Wednesday.Approximately 160 million light years from Earth, the pair is the nearest known such phenomenon.The black holes are located near the center of the spiral galaxy NGC 3393. Separated by only 490 light years, the black holes are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago.Both of the supermassive black holes are heavily obscured by dust and gas, which makes them difficult to observe in optical light. Because X-rays are more energetic, they can penetrate this obscuring material. Chandra's X-ray spectra show clear signatures of a pair of supermassive black holes."If this galaxy weren't so close, we'd have no chance of separating the two black holes the way we have," said Pepi Fabbiano of the Harvard-Smithsonian Center for Astrophysics, who led the study that appeared Wednesday in on-line issue of the journal Nature. "Since this galaxy was right under our noses by cosmic standards, it makes us wonder how many of these black hole pairs we've been missing."Previous observations in X-rays and at other wavelengths indicated that a single supermassive black hole existed in the center of NGC 3393. However, a long look by Chandra allowed the researchers to detect and separate the dual black holes. Both black holes are actively growing and emitting X-rays as gas falls towards them and becomes hotter.When two equal-sized spiral galaxies merge, astronomers think it should result in the formation of a black hole pair and a galaxy with a disrupted appearance and intense star formation. A well-known example is the pair of supermassive black holes in NGC 6240, which is located about 330 million light years from Earth.However, NGC 3393 is a well-organized spiral galaxy, and its central bulge is dominated by old stars. These are unusual properties for a galaxy containing a pair of black holes.

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LOS ANGELES, Sept. 10 (Xinhua) -- Scientists at the University of California Los Angeles campus have announced that they have successfully used new prediction algorithms to forecast climate up to 16 months in advance.Professor Michael Ghil said in a UCLA news release Friday his team used new prediction algorithms based on matching ocean temperature records with new theories on how long-term climate trends are influenced by short-term weather extremes.That's twice as far into the future as previously accomplished.Ghil, a distinguished professor of climate dynamics in the UCLA Department of Atmospheric and Oceanic Sciences and senior author of the research, said the new prediction formulas will give climate experts and governments clues about long-term swings in the El Nino/La Nina oscillation in the Pacific Ocean, which drastically affects weather in the Americas, Asia and Australia.The new forecasting tool uses sea temperatures and has been tested on decades of historical data. The forecasts were then cross-checked against actual climate trends.The UCLA team also said that their 16-month forecasts were more accurate than previous forecasts that went only 8 months forward.Ghil emphasized that the forecasting tools are for climate, which is long-range, global patterns, but not for meteorology, which is short-term weather forecasting."Certain climate features might be predictable, although not in such detail as the temperature and whether it will rain in Los Angeles on such a day two years from now," said Ghil, who is also a member of UCLA's Institute of Geophysics and Planetary Physics. "These are averages over larger areas and longer time spans."The study is currently available online in the journal Proceedings of the National Academy of Sciences (PNAS) and will be published in an upcoming print edition of the journal.

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XICHANG, Sichuan, June 21 (Xinhua) -- China successfully launched a new communication satellite, the Zhongxing-10, from its Xichang Satellite Launch Center in southwest Sichuan Province on early Tuesday.The satellite, carried by a Long March-3B rocket carrier, blasted off from the center at 0:13 a.m., said a statement from the center.According to statistics from the control center, the satellite successfully separated from its carrier rocket and entered Earth's orbit as scheduled, 26 minutes after being launched.The Zhongxing-10 was designed and manufactured by the China Academy of Space Technology under the China Aerospace Science and Technology Corporation.The satellite will provide communication, broadcasting and data transmission services for users in China and the Asia-Pacific region. It will replace the Zhongxing-5B satellite, which was launched in 1998.The launch was the 138th mission for the Long March carrier rocket series.

  

CANBERRA, Sept. 23 (Xinhua) -- A genetic study on Friday found Aboriginal Australians are descended from the first people to leave Africa up to 75,000 years ago.Researchers from the University of Western Australia, Murdoch University and an international team analyzed genetic material of a 100-year-old West Australian Aboriginal man's hair, and found he was directly descended from a migration out of Africa into Asia.The study revealed that Australian Aboriginal ancestors split from the first modern human populations to leave Africa, between 64,000 and 75,000 years ago, at least 24,000 years before other human migrations.According to Dr. Joe Dortch, an archaeologist at the University of Western Australia, the discovery rewrites the history of the human species by confirming humans moved out of Africa in waves of migrations rather than in one single out-of-Africa diaspora.It also rewrites the story about how Aborigines arrived in Australia some 50,000 years ago."So far there are no [archaeological] sites that are over 50, 000 years old so it puts a time limit on that and focuses our future efforts," he said in a statement released on Friday.Dr. Dortch believes the finding will foster a sense of pride in modern Australian Aborigines."No-one else in the world can say 'I am descended from people who have been here 75,000 years'."Associate Professor Darren Curnoe, leader of the Human Evolutionary Biology Lab in the School of Biological, Earth & Environmental Sciences at the University of New South Wales, said the study powerfully confirms that Aboriginal Australians are one of the oldest living populations in the world, certainly the oldest outside of Africa."Australians are truly one of the world's great human populations and a very ancient one at that, with deep connections to the Australian continent and broader Asian region. About this now there can be no dispute," he told Xinhua in an email note.Meanwhile, Professor Alan Cooper, Director of the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, said while this is a major step forward, the key unresolved question remains the unique story of Aboriginal history within Australia, such as what has happened in those 50,000 years of life in the harsh Australian environment."Unfortunately, the information from a single individual tells us very little about this fascinating, and critically important part of human history. Aborigines are one of the oldest continuous human populations outside Africa, as they note in the paper, and due to the geographic isolation and limited archaeological records remain one of the most mysterious chapters in human history," he told Xinhua on Friday.The study is published on Friday in the journal Science.Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. They together make up more than 2.5 percent of Australia's population.

  

SAN FRANCISCO, Sept. 22 (Xinhua) -- Former eBay Chief Executive Officer and California governor candidate Meg Whitman on Thursday was named Hewlett-Packard's new CEO, replacing Leo Apotheker who served 11 months on the job."We are fortunate to have someone of Meg Whitman's caliber and experience step up to lead HP," said the California-based company in a statement."We are at a critical moment and we need renewed leadership to successfully implement our strategy and take advantage of the market opportunities ahead," said the troubled tech giant.It noted that the job of the HP CEO now requires additional attributes to successfully execute on the company's strategy, adding Whitman "has the right operational and communication skills and leadership abilities to deliver improved execution and financial performance.""I am honored and excited to lead HP. I believe HP matters -- it matters to Silicon Valley, California, the country and the world," said Whitman in a statement.Whitman, 55, joined the HP board in January and served as president and CEO of eBay from 1998 to 2008, when she led the company through its initial public offering and massive growth.During her last years at eBay, she is blamed for not being able to halt the sales slowdown and overpaying for the 2005 acquisition of Skype with 4.1 billion dollars. In 2009, Skype was sold by eBay at a valuation of 2.75 billion dollars.Whitman won the Republican nomination for governor of California in 2010. She lost the election to Gov. Jerry Brown after spending more than 140 million dollars of her own fortune on the campaign. EnditemHP said the appointments are effective immediately, following the decision that Apotheker stepped down as president and CEO and resigned as a director of the company.Multiple U.S. media reported on Wednesday that Apotheker was to be ousted, sending HP shares soaring on the market and in the after-hour trading.Apotheker, 58, was named HP CEO 11 months ago to replace Mark Hurd, who was ousted due to a scandal over a personal relationship with a company contractor and then became co-president of Oracle. Before HP, Apotheker had served as CEO of German software giant SAP for 10 months.On Aug. 18, Apotheker announced that HP will shut down its mobile business, spin off its core personal computer business and transfer into a cloud-based software and services provider for businesses including a 10.3 billion-dollar acquisition of British software company Autonomy.Shares of the company plunged 20 percent the following day, the worst one-day loss since Black Monday in 1987.On Sept. 30, 2010, the day before Apotheker's appointment as HP CEO, the tech giant's stock closed at 42.04 dollars. On Tuesday, the price closed at 22.47 dollars, a decrease of 46.6 percent in less than a year.On Monday, HP was reported to begin sending over 500 employees pink slips in the WebOS division, after announcing to stop making WebOS devices in August.

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