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Public·60 Moonbaes
Vsevolod Chernov
Vsevolod Chernov

Barbara Nova [CRACKED]

Ananova is "the world's first virtual newscaster." Last week she began broadcasting in cyberspace with the opening, computer-generated words: "Hello world. Here is the news - and this time it's personal."

barbara nova


But Mark Hird, publishing director of Ananova Ltd., a division of the British Press Association, predicts that Ananova will rapidly become "an artificial personal assistant for hundreds of thousands of Web surfers."

In addition to viewing Ananova's virtual newscasts, surfers can ask her to produce tailored e-mail news bulletins on subjects of special interest, browse entertainment listings, and buy tickets. And they can use her as a dedicated search engine.

To make sure she doesn't giggle while giving the details of a plane crash, says Robert Simpson, Ananova Ltd.'s CEO, producers press buttons to make her expression match the tone of what she is reading.

But, commercial director Vivienne Adshead says the company spent a lot of energy honing Ananova's image. Part of that was finding that "people said they preferred to get their information from a woman."

However, the astronomers could discern that the supernova was surrounded by shells of gas, some of it containing hydrogen that had likely been cast off in previous nova eruptions, decades before the supernova occurred. These are much more frequent weak explosions that do not destroy the star.

While similar shells of material had been seen before in a handful of Type Ia supernovae, their origin was debated, and they had never before been firmly linked to novae. Some doubted that the material was even near to the supernova at all.

PTF 11kx was different. The surrounding gas was moving too slowly to be from the supernova, but too fast to be a typical stellar wind. Lars Bildsten, director of the Kavli Institute for Theoretical Physics at the University of California Santa Barbara, hypothesized that it was material shot out from a previous nova eruption, which had been slowed as it collided with the wind from the red giant star.

But if this was the case, the very fast-moving supernova ejecta should have eventually collided with the nova material. About two months after the explosion, this is exactly what happened. New observations showed that the supernova ejecta was smashing into the interior shell of material. It was impossible to doubt that this gas was near the supernova.

The team was further convinced of the nova hypothesis based on its similarity to RS Ophiuchi, a recurrent nova in our own galaxy. Unlike distant supernovae, RS Oph is close enough that its properties are known: It is a compact white dwarf star (similar to what the core of the sun will become in 5 billion years) in orbit with a red giant star.

Material that is being blown off the red giant in a stellar wind is landing on the white dwarf, and, as the material builds up, it periodically explodes as a nova eruption. RS Oph has these explosions every 20 years or so, with the last occurring in 2006.

The PTF team previously showed that SN 2011fe, the closest Type Ia supernova in 25 years, could not be a nova of the type suspected in PTF 11kx. And any red giant in the binary system is expected to survive the explosion of the white dwarf.

A recent study found no such survivor in a nearby supernova remnant and concluded that it must have been caused by the merger of two white dwarf stars. Finally, other studies showed that some supernovae are so bright that they almost certainly result from the merger of two white dwarf stars.

Predicting the exact number of supernovae that may arise from novae is difficult, since the authors think they got lucky and saw the nova at just the right angle so that they could infer its presence.

But novae look very different from different directions, so if they had seen the explosion from a different perspective, they might have missed it. Still, they estimate that novae give rise to more than one-tenth of a percent of all Type Ia supernovae, but less than 20 percent.

Andy Howell, second author on the study, says: It is a total surprise to find that thermonuclear supernovae, which all seem so similar, come from different kinds of stars. It is like discovering that some humans evolved from ape-like ancestors, and others came from giraffes. 041b061a72


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