NASA’s K2 Finds Dead Star Vaporizing a Mini “Planet”

Scientists using NASA’s repurposed Kepler space telescope, known as the K2 mission, have uncovered strong evidence of a tiny, rocky object being torn apart as it spirals around a white dwarf star. This discovery validates a long-held theory that white dwarfs are capable of cannibalizing possible remnant planets that have survived within its solar system.


“We are for the first time witnessing a miniature “planet” ripped apart by intense gravity, being vaporized by starlight and raining rocky material onto its star,” said Andrew Vanderburg, graduate student from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and lead author of the paper published in Nature.

In this artist’s conception, a tiny rocky object vaporizes as it orbits a white dwarf star. Astronomers have detected the first planetary object transiting a white dwarf using data from the K2 mission. Slowly the object will disintegrate, leaving a dusting of metals on the surface of the star.

 

Credits: CfA/Mark A. Garlick

 

 

As stars like our sun age, they puff up into red giants and then gradually lose about half their mass, shrinking down to 1/100^th of their original size to roughly the size of Earth. This dead, dense star remnant is called a white dwarf.


The devastated planetesimal, or cosmic object formed from dust, rock, and other materials, is estimated to be the size of a large asteroid, and is the first planetary object to be confirmed transiting a white dwarf. It orbits its white dwarf, WD 1145+017, once every 4.5 hours. This orbital period places it extremely close to the white dwarf and its searing heat and shearing gravitational force.


During its first observing campaign from May 30, 2014 to Aug. 21, 2014, K2 trained its gaze on a patch of sky in the constellation Virgo, measuring the minuscule change in brightness of the distant white dwarf. When an object transits or passes in front of a star from the vantage point of the space telescope, a dip in starlight is recorded. The periodic dimming of starlight indicates the presence of an object in orbit about the star.

The diagram depicts a model of light curve shapes. The red line indicates the symmetric shape of a hypothetical Earth-size planet transit while the blue line is the asymmetric shape of the tiny disintegrating planet and its comet-like trailing dusty tail. The black dots are measurements recorded by the K2 mission of WD 1145+017.

Credits: CfA/A. Vanderburg

 

 

A research team led by Vanderburg found an unusual, but vaguely familiar pattern in the data. While there was a prominent dip in brightness occurring every 4.5 hours, blocking up to 40 percent of the white dwarf's light, the transit signal of the tiny planet did not exhibit the typical symmetric U-shaped pattern. It showed an asymmetric elongated slope pattern that would indicate the presence of a comet-like tail. Together these features indicated a ring of dusty debris circling the white dwarf, and what could be the signature of a small planet being vaporized.


“The eureka moment of discovery came on the last night of observation with a sudden realization of what was going around the white dwarf. The shape and changing depth of the transit were undeniable signatures,” said Vanderburg.


In addition to the strangely shaped transits, Vanderburg and his team found signs of heavier elements polluting the atmosphere of WD 1145+017, as predicted by theory.


Due to intense gravity, white dwarfs are expected to have chemically pure surfaces, covered only with light elements of helium and hydrogen. For years, researchers have found evidence that some white dwarf atmospheres are polluted with traces of heavier elements such as calcium, silicon, magnesium and iron. Scientists have long suspected that the source of this pollution was an asteroid or a small planet being torn apart by the white dwarf's intense gravity.


Analysis of the star's atmospheric composition was conducted using observations made by the University of Arizona's MMT Observatory.

Read more here:http://www.nasa.gov/ames/kepler/nasa-k2-finds-dead-star-vaporizing-mini-planet

Red Wolf Still In Texas?

In case you've not checked the blog roll, Cryptomundo has posted  Red wolf-like animals still in Texas?  So if you are interested in canids check it out.
 

Is It Possible Scientists may have found the earliest evidence of life on Earth?

But you'll notice if you visit the page it's still "maybe"/"might not be"/"Could be"!

Julia Rosen

http://news.sciencemag.org/biology/2015/10/scientists-may-have-found-earliest-evidence-life-earth 

 

When did life on Earth begin? Scientists have dug down through the geologic record, and the deeper they look, the more it seems that biology appeared early in our planet’s 4.5-billion-year history. So far, geologists have uncovered possible traces of life as far back as 3.8 billion years. Now, a controversial new study presents potential evidence that life arose 300 million years before that, during the mysterious period following Earth’s formation.

 
The clues lie hidden in microscopic flecks of graphite—a carbon mineral—trapped inside a single large crystal of zircon. Zircons grow in magmas, often incorporating other minerals into their crystal structures of silicon, oxygen, and zirconium. And although they barely span the width of a human hair, zircons are nearly indestructible. They can outlast the rocks in which they initially formed, enduring multiple cycles of erosion and deposition.


In fact, although the oldest rocks on Earth date back only 4 billion years, researchers have found zircons up to 4.4 billion years old. These crystals provide a rare glimpse into the first chapter of Earth’s history, known as the Hadean eon. “They are pretty much our only physical samples of what was going on on the Earth before 4 billion years ago,” says Elizabeth Bell, a geochemist at the University of California, Los Angeles (UCLA), and lead author of the new study, published online today in the Proceedings of the National Academy of Sciences.
  

Image by Robert Simmon, based on data from the University of Maryland’s Global Land Cover Facility

In the study, Bell and her colleagues examined zircons from the Jack Hills in Western Australia, a site that has yielded more Hadean samples than anywhere else on Earth, searching for inclusions of carbon minerals like diamonds and graphite. The mere presence of these minerals does not prove biology existed when the zircons formed, but it does provide the opportunity to look for chemical signs of life. The team eventually found small bits of potentially undisturbed graphite in one 4.1 billion-year-old crystal. The graphite has a low ratio of heavy to light carbon atoms—called isotopes—consistent with the isotopic signature of organic matter. “On Earth today, if you were looking at this carbon, you would say it was biogenic,” Bell says. “Of course, that’s more controversial for the Hadean.”


The authors list several nonbiological processes that could explain their findings, but they favor the idea that the graphite started out as organic matter in sediments that got dragged into the Earth’s mantle during the collision of tectonic plates. As the sediments melted to form magma, the elevated temperatures and pressures transformed the carbon into graphite, which eventually found its way into a zircon crystal.


If this story is true, and life existed 4.1 billion years ago, Bell says that the new results would corroborate growing evidence of a more hospitable early Earth than scientists once imagined. “The traditional view of the Earth’s first few hundred million years was that this was a sterile, lifeless, hot planet that was constantly being bombarded by meteorites,” she says. But partly thanks to the wealth of information revealed by the Jack Hills zircons in recent years, scientists have come to see the early Earth as much milder and more amenable to life.


“We know there was liquid water,” says Mark van Zuilen, a geomicrobiologist at the Paris Institute of Earth Physics. “There’s nothing that holds us back from assuming life was there.” However, van Zuilen and others say they’re not sure the new study provides compelling evidence that it was.


Some of this circumspection has roots in recent history. In 2008, researchers announced that diamond-graphite inclusions in 4.3-billion-year-old zircons had potentially biological signatures, inspiring Bell and her team to start looking through UCLA’s own collection of Jack Hills crystals. But subsequent analysis showed the 2008 inclusions came from lab contamination, not early Earth. In the new study, the researchers took measures to prevent similar problems.


“That one negative experience doesn’t mean nobody should try again,” says John Eiler, a geologist at the California Institute of Technology in Pasadena. “But let’s just say, I’m cautious.” For one, he says, researchers need to settle some important debates, like whether the inclusions in Hadean zircons truly preserve original material, or if they’ve been altered, for example, during a later bout of metamorphism. He also questions whether organic matter can survive in magma chambers long enough to form graphite, casting doubt on the proposed mechanism.


Those issues aside, most scientists—including the authors—agree that the data do not yet exclude nonbiological explanations. Many abiotic processes can produce carbon with isotopic signatures similar to organic matter. For instance, the graphite could contain carbon from certain kinds of meteorites, which have light isotopic compositions. Alternatively, some invoke chemical processes, like the so-called Fischer-Tropsch reactions, in which carbon, oxygen, and hydrogen react with a catalyst like iron to form methane and other hydrocarbons. Such reactions probably occurred near hydrothermal vents in the Hadean, van Zuilen says, and can impart isotopic signatures that are indistinguishable from biological materials.


One way to settle the question that doesn’t rely on isotopes involves studying Mars, which, unlike Earth, still has rocks older than 4 billion years on its surface. “If we can find evidence for the existence of life on Mars at that time, then it will be easier to argue the case that it was also present on Earth,” says Alexander Nemchin, a geochemist at Curtin University in Bentley, Australia, and lead author of the 2008 study on diamond inclusions.


For now, scientists must make do with zircons, the only materials that preserve any record—however cryptic—of the Hadean eon. Bell acknowledges the need to test her team’s hypothesis on additional samples. She says researchers must make a concerted effort to find more Hadean carbon in Jack Hills zircons and see if it too has potentially biological origins. “Hopefully we didn’t just chance on the one freak zircon that had graphite in it,” she says. “Hopefully there is actually a fair amount of it.”