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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.

BEIJING, Aug. 3 (Xinhuanet) -- NASA Tuesday confirmed a 4-foot in diameter sphere debris as a fuel tank that was part of the space shuttle Columbia's electrical power system,according to U.S. news reports.NASA engineers identified the 4-foot piece of spherical debris as one of the18 tanks that held chilled oxygen and hydrogen used by the shuttle's electricity-generating fuel cells.This Aug. 1, 2011 handout photo provided by the Nacogdoches Police Department shows a 4-feet in diameter sphere found in Lake Nacogdoches, Texas on Monday, Aug. 1. Police say low water levels at the lake during the drought have led to recovery of a container-like object that could be from space shuttle Columbia. The shuttle broke apart and burned in February 2003, scattering remnants over East TexasPolice in the city of Nacogdoches, about 160 miles northeast of Houston, said Monday the low water levels of Lake Nacogdoches during the record drought revealed an unexpected object that could be from space shuttle Columbia. The shuttle broke apart and burned as it re-entered the atmosphere on February 1, 2003.The tank will be moved to the Kennedy Space Center, where the rest of the Columbia is stored. Approximately 40 percent of the spacecraft has been recovered.

SAN FRANCISCO, June 28 (Xinhua) -- Google has launched a new site wdyl.com, a search service standing for "what do you love" and integrating a variety of Google's search products on one page.According to a report by technology blog TechCrunch, wdyl.com was quietly rolled out several days ago and the formal launch was set for Monday, but engineering issues have been holding it back until early Tuesday morning.The site can return users a single page of relevant results across a variety of Google's search services for whatever query is typed into the search box, whose search button is even a heart.For example, after typing in "pasta," several columns appear on the search results page, allowing users to see images of pasta, watch videos of pasta, or browse latest news about pasta.Other search results include pasta-related maps, books, blogs, patents, translation, popularity on the web and etc.

CHENGDU, Sept. 3 (Xinhua) -- A list of this year's top 500 Chinese enterprises was unveiled in the city of Chengdu in southwest China's Sichuan Province on Saturday.The Sinopec Group was ranked first, with last year's revenues reaching 1.97 trillion yuan (307.81 billion U.S. dollars), followed by the China National Petroleum Corp. and State Grid Corp., whose revenues hit 1.72 trillion yuan and 1.53 trillion yuan last year, respectively.The rest of the top 10 was rounded out by the Industrial and Commercial Bank of China, China Mobile, China Railway Group, China Railway Construction Corp., China Construction Bank, China Life Insurance Co. and Agricultural Bank of China.The list is the 10th of its kind to be jointly released by the China Enterprise Confederation and the China Enterprise Directors Association. The threshold for entering the list was raised to 14.2 billion yuan in revenues, an increase over the 11.08-billion-yuan threshold used during the previous year.Revenues for China's top 500 companies rose 31.6 percent year-on-year to 36.31 trillion yuan in 2010, while their total assets increased by 18.4 percent to 108.1 trillion yuan, the two organizations said.The companies reported profits of 2.08 trillion yuan for last year, a rise of 38.67 percent from one year earlier.They paid 2.73 trillion yuan in taxes in 2010, accounting for 37.3 percent of the country's total tax revenues.

BEIJING, July 6 (Xinhua) -- The Ministry of Health has issued a national standard on compound food additives to better regulate the production and use of such additives and ensure food safety.Compound food additives, which are designed to improve food quality or assist in food processing, should be used sparingly in food products, according to the standard the ministry issued Tuesday.Titled the General Rule on Compound Food Additives, the standard stipulates that each of the ingredients used for making compound food additives, which are a mix of two or more single food additives, should meet national standards concerning food safety.No chemical reaction should occur and no new compounds should be generated during the production process of compound food additives, according to the standard.Compound food additives producers should clarify limits of the amounts of harmful substances, such as lead and arsenic, in their products and take measures to control the levels of harmful substances, according to the standard, which will come into effect on Sept. 5 this year.