Dead Star Warps Light of Companion Red Star, Astronomers Say

NASA's Kepler space telescope, in concert with Cornell-led measurements of stars' ultraviolet activity, has observed the effects of a dead star bending the light of its companion red star.

The findings are among the first detections of this effect -- a result predicted by Einstein's theory of general relativity -- in binary, or double, star systems.

The dead star, also called a white dwarf, is the burnt-out core of what used to be a star like our sun. It is locked in an orbiting dance with its partner, a small "red dwarf" star. While the tiny white dwarf is physically smaller than the red dwarf, it is more massive. When the white dwarf passed in front of its star, its gravity caused the starlight to observably bend and brighten.

"This white dwarf is about the size of Earth but the mass of the sun," said Phil Muirhead, Ph.D. '11, of the California Institute of Technology and lead author of the findings to be published April 20 in the Astrophysical Journal, titled "Characterizing the cool KOIs: A mutually eclipsing post-common envelope binary."

"It's so hefty that the red dwarf, though larger in physical size, is circling around the white dwarf," Muirhead continued.

The research team used Cornell-led ultraviolet measurements of the star called (Kepler Object of Interest) KOI-256 taken by the Galaxy Evolution Explorer (GALEX), a NASA space telescope operated by Caltech. The GALEX observations were conducted by Cornell researchers Jamie Lloyd, associate professor of astronomy and of mechanical and aerospace engineering; Kevin Covey, former postdoctoral associate now at Lowell Observatory; and Lucianne Walkowicz of Princeton University and Evgenya Shkolnik of Lowell Observatory.

Still in early phases and for which Cornell students are now being recruited by Lloyd, the GALEX program measures ultraviolet activity in all the stars in the Kepler field of view -- an indicator of potential habitability for planets.

Graduate student and co-author Jim Fuller also did a theoretical analysis of the star system in the context of its future and past evolutions.

The red dwarf orbits the white dwarf in just 1.4 days. This orbital period is so short that the stars must have previously undergone a "common-envelope" phase in which the red dwarf orbited within the outer layers of the star that formed the white dwarf, Fuller explained.

Moreover, the short orbital period means the red dwarf's days are numbered: In a few billion years, the intense gravity of the white dwarf will strip material off the red dwarf, forming a hot accretion disk of in-falling material around the white dwarf.

"This system is especially exciting because it allows us to accurately characterize the peaceful state of these systems before the violent mass-transfer phase begins," Fuller said.

 

Kepler's primary job is to scan stars in search of orbiting planets. As the planets pass by, they block the starlight by miniscule amounts, which Kepler's sensitive detectors can see.

So far, Kepler has identified more than 2,700 planet candidates. Still ongoing is the mission's search for planets similar to Earth in size and temperature that orbit a star like our sun. Ultimately, Kepler will reveal how common Earth-size planets are in the Milky Way galaxy.

To learn more about this particular star system, Muirhead and colleagues also used the Hale Telescope at Palomar Observatory near San Diego. Using a technique called radial velocity, they discovered that the red dwarf was wobbling around like a spinning top. The wobble was too big to be from the tug of a planet. That's when they knew they were looking at a massive white dwarf passing behind the red dwarf, rather than a gas giant passing in front.

One of the consequences of Einstein's theory of general relativity is that gravity bends light. Astronomers regularly observe this phenomenon, often called gravitational lensing, which has been used to discover new planets and hunt for free-floating planets.

In this new study, scientists used gravitational lensing to determine the mass of the white dwarf. By combining this information with all the data they acquired, they were able to accurately measure the mass of the red dwarf and the physical sizes of both stars.

Source story:Science Daily

N.H.Khidr

Universe older than thought

Planck space telescope shows the most detailed map ever created of the cosmic microwave background.

The universe is 100 million years older than thought, according to the best-ever map of the oldest light in space.

Europe’s Planck space observatory looked back at the afterglow of the Big Bang, and those results have now added about 80 million years to the universe's age, putting it at 13.81 billion years old, according to Voice of Russia, SPACE.com

The adjustment also means space and time are expanding slightly slower than scientists thought.

These discoveries come from a new all-sky map of ancient cosmic light by the Planck probe, which has measured what's called the cosmic microwave background in greater detail than ever before.

R.S

Apple apologizes to Chinese consumers

Apple apologised to Chinese consumers after government media attacked its repair policies for two weeks in a campaign that reeked of economic nationalism.

A statement Apple posted in Chinese on its website said the complaints had prompted "deep reflection" and persuaded the company of the need to revamp its repair policies, boost communication with Chinese consumers and strengthen oversight of authorised resellers.

State broadcaster CCTV and the ruling party's flagship newspaper, People's Daily, had led the charge against the American company.

They accused Apple of arrogance, greed and "throwing its weight around" and portrayed it as just the latest Western company to exploit the Chinese consumer.

The attacks quickly backfired, though, and were mocked by the increasingly sophisticated Chinese consumers who revere Apple and its products. State-run media also inadvertently revived complaints over shoddy service by Chinese companies.

Nonetheless, Apple responded with an apology from CEO Tim Cook.

"We've come to understand through this process that because of our poor communication, some have come to feel that Apple's attitude is arrogant and that we don't care about or value feedback from the consumer," his Chinese statement said.

"For the concerns and misunderstandings passed on to the consumer, we express our sincere apologies."

Although Apple enjoys strong support from Chinese consumers, the vehemence of the attacks and the importance of the Chinese market appeared to have persuaded the company to smooth its relations with Chinese consumers and authorities.

The People's Daily newspaper ran an editorial last Wednesday headlined: "Strike down Apple's incomparable arrogance."

It wrote: "Here we have the Western person's sense of superiority making mischief.

"If there's no risk in offending the Chinese consumer, and it also makes for lower overheads, then why not?"

Chinese observers accused People's Daily of gross hypocrisy and pointed out that the newspaper had maintained a stony silence when Chinese companies were implicated over food safety, pollution and other scandals.

Meanwhile, CCTV was shamed when it emerged that celebrities had been recruited to blast the company on Weibo, China's version of Twitter, in what had been billed as a grassroots campaign.

Popular business magazine Caijing said its readers identified a long list of abusers, including state banks that lend to those with political connections while leaving ordinary savers with low rates on deposits.

A government oil company that sets gas prices and other rates as it sees fit, and state telecom providers notorious for their lack of customer service were also criticised.

Source: Associated press

B.N

Google Plans to Shut Down You Tube Till 2023

 

 

Google announced it was planning to shut down YouTube, the world's most popular video-sharing website, till 2023, according to the Voice of Russia.

 In April Fools’ prank video the company declared the site had been in an eight-year contest to find the best video and now the company’s specialists needed a decade to review all the videos and select the winner.

"Tonight at midnight, youtube.com will no longer be accepting entries. After eight amazing years, it is finally time to review everything that has been uploaded to our site and begin the process of selecting a winner," said the video clip.

The winner will get a $500 stipend a clip-on MP3 player and his video will become the sole video to be featured on YouTube when the website re-launches in 2023, the prank video adds.

At the moment the YouTube audience is estimated at 1 billion people.

 Launched in 2005 as a start-up, the You Tube is now described as “one of the most influential forces in today's media landscape.”

In 2006 Google bought You Tube for $1.76 billion, then the web-site’s audience was estimated at 50 million people per month.

H.M

 

 

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