Archive for the ‘Space’ Category

ANN ARBOR, Mich.—Using the deepest X-ray image ever taken, a University of Michigan astronomer and her colleagues have found the first direct evidence that massive black holes were common in the early universe. This discovery from NASA’s Chandra X-ray Observatory shows that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies.

By pointing Chandra at a patch of sky for over six weeks, astronomers obtained what is known as the Chandra Deep Field South (CDFS). When combined with very deep optical and infrared images from NASA’s Hubble Space Telescope, the new Chandra data allowed astronomers to search for black holes in 200 distant galaxies, from when the universe was between about 800 million and 950 million years old.

“We had reason to expect that black holes existed in many of the very first galaxies, but they had evaded our searches until now. When I compared Chandra’s data to my theoretical models I was stunned by their agreement. It’s the dream of any theoretician,” said Marta Volonteri, a U-M associate professor of astronomy and co-author of the study that appears in this week’s Nature.

The super-sized growth means that the black holes in the CDFS are related to quasars, very luminous, rare objects powered by material falling onto supermassive black holes. However, the sources in the CDFS are about a hundred times fainter, and the black holes are about a thousand times less massive than the ones in quasars.

It was found that between 30 percent and 100 percent of the distant galaxies contain growing supermassive black holes. Extrapolating these results from the small observed field to the full sky, there are at least 30 million supermassive black holes in the early Universe. This is a factor of 10,000 larger than the estimated number of quasars in the early Universe.


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Drs. Stephen Potter and Encarni Romero-Colmenero from the South African Astronomical Observatory (SAAO) and collaborators have found evidence for the existence of an extraordinary planetary system where two giant planets are orbiting a close pair of “suns”.

If confirmed, this will be an example of a very strange planetary system, given the nature of the stellar pair. The two stars, referred to as a white dwarf and a red dwarf, are each smaller than our Sun and are so close that they take only a couple of hours to orbit each other. The pair of them would actually fit comfortably within our Sun! By chance, the system is oriented in such a way that the stars appear to eclipse each other once every orbit as viewed from Earth. Dr. Potter and his collaborators noticed that the eclipses were not occurring on time, but were sometimes too early or too late. This led them to hypothesize the presence of two giant planets whose gravitational effect would cause the stars’ orbit to wobble and consequently slightly alter the measured time between eclipses. The astronomers were also able to infer that the masses of the two planets must be at least  6 and 8 times that of Jupiter and take 16 and 5 years respectively to orbit the two stars. The system is too far away from us to be imaged directly.

This binary star system (known as UZ For) would be an extremely inhospitable environment. Due to their close proximity, the gravity of the white dwarf is constantly “stealing” material from the surface of the red dwarf in a continuous stream. This stream crashes onto the white dwarf where it gets super-heated to millions of degrees and subsequently floods the entire planetary system with enormous amounts of deadly X-rays.

This discovery was made possible by new SAAO and Southern African Large Telescope (SALT) observations combined with archival data spanning 27 years, gathered from multiple observatories and satellites.

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The VLT Survey Telescope (VST) is the latest telescope to be added to ESO’s Paranal Observatory in the Atacama Desert of northern Chile. It is housed in an enclosure immediately adjacent to the four VLT Unit Telescopes on the summit of Cerro Paranal under the pristine skies of one of the best observing sites on Earth.

The VST is a wide-field survey telescope with a field of view twice as broad as the full Moon. It is the largest telescope in the world designed to exclusively survey the sky in visible light. Over the next few years the VST and its camera OmegaCAM will make several very detailed surveys of the southern sky. All survey data will be made public.

The first released VST image shows the spectacular star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula, as it has never been seen before. This vast region of gas, dust and hot young stars lies in the heart of the Milky Way in the constellation of Sagittarius (The Archer). The VST field of view is so large that the entire nebula, including its fainter outer parts, is captured — and retains its superb sharpness across the entire image. The data were processed using the Astro-WISE software system developed by E.A. Valentijn and collaborators at Groningen and elsewhere.


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