Scientists have discovered that the sun and its nearest twin star, Alpha Centauri A, share an odd solar quirk: a puzzling cool layer in their wispy, hot atmospheres.

Astronomers have captured what may be the first-ever direct photograph of an alien planet in the process of forming around a nearby star.

LOS ANGELES — By taking a fresh look at old data, an international team of astronomers has discovered a possible super-Earth planet relatively nearby that could potentially hold liquid water, scientists announced last week.

The research, released by the journal Astronomy Astrophysics, used a novel technique to analyze previous measurements of a nearby star. The paper drew some praise even as other experts in the field expressed caution about the results.

The finding adds three planet candidates around the dwarf star HD 40307, about 42 light-years away. Combined with three others that were discovered in 2008, they bring the total to six. Five are clustered close to the star, nearer than Mercury’s orbit around the sun.

But one of the three new finds lies far enough away to be in what’s known as the habitable zone, where a planet could support liquid water — and perhaps life.

That candidate planet, dubbed HD 40307g, has seven times the mass of Earth, the scientists reported.

“It’s likely that it’s sufficient in mass that it does have an atmosphere,” said co-author Hugh Jones, an astronomer at the University of Hertfordshire in England. “But we don’t know.”

It’s difficult to draw extensive conclusions about such super-Earths because no such mid-range planet exists in our own solar system. But Jones did say that HD 40307g is far enough way from its star to be able to rotate freely and possibly have a proper night and day, making it even more likely to have an Earth-like climate. The closer-in planets are gravitationally locked into the star’s motion, just as the moon is locked into Earth’s, which is why we only see one side of it.

Although the planet appears somewhat closer to its star than Earth is to the sun, the dwarf star is also smaller and dimmer than the one at the center of our solar system.

Jones and his collaborators found the new planet by looking through old measurements collected by the 3.6-meter telescope at La Silla Observatory in Chile. They used a technique called the radial velocity method, which takes advantage of the Doppler effect.

The finding has yet to be confirmed by other analysis or observations. Not everyone is convinced this particular planet exists.

Francesco Pepe of the Geneva Observatory said his team already had seen the signals described in the new paper. In fact, they originally produced the data in question.

“These signals are, however, at the edge of detectability and some doubts remain(ed) on their planetary nature,” Pepe wrote in an email. “It is our policy to exclude any possible other explanation and to collect sufficient data to confirm the (possible) additional planets.”

Article source: http://www.bendbulletin.com/article/20121114/NEWS0107/211140350/

Twinkling stars are not the only diamonds in the sky. Scientists on Thursday reported the existence of a “diamond planet” twice the size of Earth, and eight times its mass, zooming around a nearby star.

In fact, this is not the first diamond planet ever discovered, but it is the first found orbiting a sun-like star and whose chemical makeup has been specified.

The discovery means that distant rocky planets can no longer be assumed to have chemical constituents, interiors, atmospheres, or biologies similar to those of Earth, said lead researcher Nikku Madhusudhan, a Yale postdoctoral researcher in physics and astronomy.

The planet was first observed last year — but researchers initially assumed it was similar in its chemical make-up to Earth.

It was only after a more detailed analysis that the French-American research team determined the planet is vastly different from our own.

It “appears to be composed primarily of carbon (as graphite and diamond), iron, silicon carbide, and, possibly, some silicates,” the authors wrote in a statement ahead of their findings’ publication in the US journal Astrophysical Journal Letters.

“The surface of this planet is likely covered in graphite and diamond rather than water and granite,” he explained.

In fact, the planet, dubbed Cancri 55 e, appears to have no water at all. And as much as a third of the planet’s substantial mass could be made of diamond, a super-dense compound of carbon.

In comparison, the Earth’s interior is rich in oxygen and very poor in carbon, explained Kanani Lee, also of Yale and another of the study’s co-authors.

The researchers estimated the planet’s radius with data collected while it was transiting in front of its star.

That information, combined with an estimate of its mass, was used to model the planet’s chemical composition, based on a calculation of just what elements and compounds could result in that specific size and mass.

The planet’s orbit around its star is lightning fast — a year lasts just 18 hours, compared to the 365 days of an Earth year. And because it is so close to its star, the surface temperatures average 3,900 degrees Fahrenheit (2,148 degrees Celsius), rendering it completely inhospitable to life.

But the planet — 40 light years away from Earth in the Cancer constellation — opens new avenues for studying geochemical and geophysical processes of Earth-sized planets outside our solar system.

Article source: http://www.thehindubusinessline.com/news/science/article3990752.ece

A few degrees from the center of our galaxy, a black hole feeding off a nearby star is caught belching a sudden outburst of X-rays in a telltale pattern. NASA’s Swift satellite spotted this secretive pair 20-30 million light years from Earth.

Heated by a nearby star, this cloud of gas and dust forms the familiar shape of an equine head.

Washington: Astronomers have been baffled by an extraordinary amount of dust around a nearby star disappearing mysteriously.

“It’s as if the rings around Saturn had disappeared. This is even more shocking because the dusty disc of rocky debris was bigger and much more massive than Saturn’s rings,” said Benjamin Zuckerman, study co-author and professor of physics and astronomy at the University of California – San Diego (UCSD).

“The disc around this star, if it were in our solar system, would have extended from the sun halfway out to Earth, near the orbit of Mercury,” Zuckerman was quoted as saying in the journal Nature.

“It’s like the classic magician’s trick – now you see it, now you don’t,” said Carl Melis, post-doctoral scholar at the UCSD, who led the research. “Only in this case, we’re talking about enough dust to fill an inner solar system, and it really is gone!”

The cosmic vanishing act occurred around a star some 450 light years from Earth, in the direction of the constellation Centaurus, according to a university statement.

“A perplexing thing about this discovery is that we don’t have a satisfactory explanation to address what happened around this star,” said Melis. “The disappearing act appears to be independent of the star itself, as there is no evidence to suggest that the star zapped the dust with some sort of mega-flare or any other violent event.”

Melis describes the star, designated TYC 8241 2652, as a “young analog of our sun” that only a few years ago displayed all of the characteristics of “hosting a solar system in the making,” before transforming completely. Now, very little of the warm, dusty material thought to originate from collisions of rocky planets is apparent.

“Nothing like this has ever been seen in the many hundreds of stars that astronomers have studied for dust rings,” Zuckerman said.

“This disappearance is remarkably fast, even on a human time scale, much less an astronomical scale. The dust disappearance at TYC 8241 2652 was so bizarre and so quick, initially I figured that our observations must simply be wrong in some strange way.”

Norm Murray, director of the Canadian Institute for Theoretical Astrophysics, who was not part of the research group, said: “The history of astronomy has shown that events that are not predicted and hard to explain can be game-changers.”

IANS

Article source: http://zeenews.india.com/news/space/astronomers-baffled-by-vanishing-act-in-space_785917.html

In late 2009 scientists noticed a periodic dimming of a nearby star and announced the discovery of a “super-Earth” about 2.7 times the size of our planet. They thought the planet GJ1214b could be made mostly of water, but they weren’t sure.

Now, using the Hubble Space Telescope to study the color of sunset (in the infrared portion of the spectrum) on this world, astronomers say the planet is very likely made mostly of water.

The water world is close to its star, which is one-fifth the size of the Sun. (NASA, ESA, and Z. Berta)

In their forthcoming paper (see .pdf) in the Astrophysical Journal, the researchers say the world likely has a dense atmosphere of water vapor, and that its interior is wholly unlike our own.

The high temperatures and high pressures would form exotic materials like ‘hot ice’ or ‘superfluid water,’ the astronomers say.

This planet is only about 40 light years from Earth, so it would be a good candidate for study by the James Webb Space Telescope . . . if it’s ever completed.

Article source: http://blog.chron.com/sciguy/2012/02/astronomers-say-nearby-planet-is-a-water-world/