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Astronomers find oldest solar twin

Our Sun is approximately 4.6 billion years old, far older than humankind, and still older than our ability to observe it with telescopes. Thus, our best source for information about how the Sun has evolved and will evolve is other stars similar to our own. Those similar stars fall into one of three categories, based upon how like our Sun they are: solar-type stars, solar analogues, and solar twins, which are most similar to the Sun. Solar twins are very much like the Sun in terms of mass, temperature, and relative abundance of different chemicals, and are also the rarest of the three classes.

Their rarity makes searching for solar twins an arduous task, but worthwhile; solar twins that are different ages than the Sun can provide a tremendous quantity of data on the life stages of our own star. Now, new observations by the European Southern Observatory’s Very Large Telescope (VLT) in Chile have revealed the oldest known solar twin: HIP 102152. The new study was led by Jorge Melendez of the Universidade de São Paulo in Brazil.

Melendez and team actually studied two solar twins to more precisely determine their ages and chemical compositions. One of the stars, 18 Scorpii, was found to be quite a bit younger than the Sun, at only 2.9 billion years old. In contrast, HIP 102152 turned out to be nearly twice as old as the Sun, 8.2 billion years old, providing a unique opportunity to learn what our Sun will be like when it reaches that great age.

In particular, HIP 102152 has shed light on an enduring mystery surrounding the chemical abundances within our Sun. Melendez and colleagues used the UVES spectrograph on the VLT, which splits light into its component colors to reveal the chemical composition and other properties of the object that emitted the light – in this case, the stars 18 Scorpii and HIP 102152. The spectrographic data indicated that HIP 102152 contains less lithium than the Sun.

Scientists have long puzzled over why the Sun contains only 1% of the lithium that was present in the matter from which it originated. Previous studies showed that younger solar twins, such as 18 Scorpii, contain significantly higher abundances of lithium. Now, the new findings about HIP 102152 suggest that lithium content does decrease as a star ages, though the mechanism behind this remains unknown.

HIP 102152 is also remarkable in that its chemical composition is subtly different from other solar twins, but very similar to that of the Sun, showing a dearth of elements that are common in rocky planets, such as Earth and Mars. Also, information from the HARPS spectrograph indicates that there are no giant gas planets in the star’s habitable zone that could disrupt the formation of rocky planets.

The new research will be published in the Astrophysical Journal Letters.

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Story: Anthony Weiner paying for supporters

Anthony Weiner’s road to the New York mayoral primary got a bit rockier after reports surfaced in The New York Post that the former congressman was paying actors to boost the crowds at his campaign events.

On Wednesday, the Post reported that Weiner’s campaign was working with Crowds on Demand, a company that specializes in providing crowds of actors for a price.

According to the Post’s source, the campaign reached out to the California business after new revelations of inappropriate behavior surfaced.  Sydney Leathers, an Indiana woman who had been in contact with Weiner even after his resignation from Congress, came forward earlier this summer. His campaign has been on the defensive ever since, losing standing in the polls and trying to regain its footing after the rehabilitation narrative had been shown false.

One of the most recent instances of the campaign’s use of “rent-a-crowds” came in the Dominican Day Parade on August 11. In that event, actors were paid $15 an hour to provide enthusiastic backing for the candidate.

Crowds on Demand did not comment, but Weiner spokeswoman Barbara Morgan told the Post that they had  “never heard of this company and certainly never used them.”

“We are proud we’ve always had the biggest and most fired-up crowds,” she also said. “That’s enthusiasm the other campaigns just can’t buy.”

The Post’s source, however, said that the Santa Monica-based Crowds on Demand was tasked with providing people who could act as if they were “either supporters or people who met him and became supporters as a result of that encounter.” Besides bolstering the number of existing supporters, the goal was apparently also to show that people skeptical of his candidacy would be convinced by meeting and talking to him.

Weiner could use the show of support given that he’s gone from frontrunner to fourth place in the crowded mayoral field in less than a month, according to the most recent poll from Quinnipiac University. New York City Public Advocate Bill de Blasio has the backing of 36% of likely Democratic voters, while only 8% say they would vote for Weiner. A month ago, Weiner was sitting at 26% and de Blasio 15%, showing just how much the race has flipped in such a short time period.

After the report was published Wednesday morning, Weiner tweeted that it was a hoax and questioned whether the Post would retract its story.

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Cassini reveals oddities of Titan’s icy shell, leaving scientists baffled

Titan, the largest moon of Saturn, is an inscrutable world. Its thick murky atmosphere is all but impenetrable to telescopes. With an equatorial radius of 1,600 miles, it is the second largest moon in the Solar System after Jupiter’s Ganymede and is even larger than the planet Mercury. Its surface is unimaginably cold, -289 degrees Fahrenheit.

Yet even the cloud-enveloped Titan is slowly yielding its secrets. NASA’s Cassini spacecraft has been orbiting Saturn since 2004, and Titan has been an object of constant interest. In January 2005, Cassini released the Huygens probe into Titan’s atmosphere; the probe landed and took the first photographs of Titan’s surface before falling silent. Cassini has continued to examine Titan with cloud-penetrating radar and other instruments, and has made a new discovery concerning the moon’s shell of ice.

The Cassini data were analyzed by Douglas Hemingway and Francis Nimmo, planetary scientists at the University of California, Santa Cruz. The fresh data concerned Titan’s gravity and topography, and revealed a counterintuitive relationship between the two properties.

“Normally, if you fly over a mountain, you expect to see an increase in gravity due to the extra mass of the mountain,” Nimmo explained in a Jet Propulsion Laboratory press release. “On Titan, when you fly over a mountain, the gravity gets lower. That’s a very odd observation.”

Hemingway, Nimmo, and colleagues developed a new model to explain these anomalous readings. They propose that each relatively small rise in Titan’s topography is offset by a deeper, iceberg-like root massive enough to overwhelm the gravitational signature of the bump on the surface, yielding the “odd observation” of the relationship between Titan’s topography and gravity. Cassini would detect less gravity because water ice is less dense than water.

“It’s like a big beach ball under the ice sheet pushing up on it, and the only way to keep it submerged is if the ice sheet is strong,” Hemingway explained. “If large roots under the ice shell are the explanation, this means that Titan’s ice shell must have a very thick rigid layer.” The ice shell would be at least 40 kilometers thick according to the model.

It is not yet clear what processes formed Titan’s topographical features and their deep roots. Titan’s surface is distorted as it orbits Saturn, generating tidal heating, which could give rise to variations in the thickness of the ice shell.

The new findings were published in the August 28 issue of the journal Nature.

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Telescope captures tumultuous birth of a star

New observations by the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed in unprecedented detail the violent events associated with the early development of a young star. The new findings involve Herbig-Haro 46/47, two objects associated with a newborn star 1,400 light-years from Earth in the southern hemisphere constellation Vela.

Herbig-Haro 46/47 are members of a strange class of phenomena known as Herbig-Haro Objects, named after the astronomers George Herbig and Guillermo Haro, who first characterized their spectra in the 1940s. Herbig and Haro concluded that the objects they observed, which were associated with areas of star formation, were generated by the force of jets of material ejected by the young stars. The jets of material travel at over one million kilometers per hour. As this material slams into the surrounding gas, it creates a structure that glows intensely – a Herbig-Haro Object.

The new study of Herbig-Haro 46/47, led by Héctor Arce of Yale University, has revealed a previously undetected jet of material shooting away from the young star. Earlier images of the region in visible light showed a single jet directed towards Earth; the new data indicate a second, receding jet directed away from Earth. The receding jet was obscured in the earlier images by dust clouds around the young star.

ALMA’s new detailed look at Herbig-Haro 46/47 allowed Arce and colleagues to measure the velocities of the ejected material. Some of the ejected matter is blasting away from the star much faster than what prior studies indicated. This suggests that the jets of gas flowing out from the star carry far more energy and momentum than expected.

“ALMA’s exquisite sensitivity allows the detection of previously unseen features in this source, like this very fast outflow,” Arce explained in a European Southern Observatory press release. “It also seems to be a textbook example of a simple model where the molecular outflow is generated by a wide-angle wind from the young star.”

So detailed are the new images from ALMA that Arce and team were able to discern another outflow from a previously unknown, less massive companion of the young star.

“The detail in the Herbig-Haro 46/47 images is stunning. Perhaps more stunning is the fact that, for these types of observations, we really are still in the early days,” said ALMA astronomer Stuartt Corder, a coauthor on the paper describing the new observations. “In the future ALMA will provide even better images than this in a fraction of the time.”

The new study will be published in the Astrophysical Journal.

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San Diego Mayor Bob Filner resigns

San Diego Mayor Bob Filner is expected to resign Friday afternoon, as part of a deal with other city officials that was reported Thursday. Over the past several weeks, Filner has come under fire for allegations of sexual harassment and the bad news only seemed to get worse for the first Democrat elected mayor of the city in more than two decades.

When Filner’s behavior as both mayor and a ten-term congressman representing San Diego in the U.S. Congress first came to light, he announced he would attend therapy. But on Wednesday, the day he was slated to return to work, he was seen carrying boxes out of his office. Word of a proposed settlement became public knowledge following three days of mediation.

City attorney Jan Goldsmith acknowledged the deal but did not go into detail about it, saying “The City Council has not heard of this proposal, and our process at City Hall as well as the mediation process requires that we maintain the confidentiality of the proposal until they have heard of it.”

According to the New York Times, the past six weeks have seen eighteen women come forward to accuse the seventy-year-old Filner of sexual harassment, including “a retired Navy rear admiral, a great-grandmother, a university dean and Mr. Filner’s former communications director, Irene McCormack Jackson.”

Jackson filed a lawsuit against Filner and the city, and it seems likely that the deal will include at least partial coverage of his legal bills.

Public pressure has increased on Filner to resign as the weeks dragged on, including from California Senator Barbara Boxer.

The San Diego City Council is expected to discuss and vote on the deal Friday afternoon in a closed session. If accepted and Filner does resign, the next step would be a special election to find his replacement. He was elected last year to his first term as mayor.

A special election is estimated to run between $3 and $6 million, and would be held within 90 days.

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NASA’s new Giant Magellan Telescope will provide images of Big Bang universe

The next generation of ground-based telescopes will take another giant leap forward on Saturday, with the completion of the third mirror for the upcoming Giant Magellan Telescope (GMT).

The GMT will commence its scientific endeavors at the Las Campanas Observatory in 2020, joining a battery of smaller telescopes in Chile’s Atacama Desert. It will feature a segmented primary mirror composed of seven monolith mirrors forming a single optical surface, and a light-capturing aperture 80 feet in diameter. The GMT will boast 10 times the resolving power of the venerable Hubble Space Telescope. It will collect more light than any telescope in history. However, before the GMT can employ these formidable advantages in scientific objectives, its mammoth mirrors must be completed.

The third such mirror will be cast in a rotating furnace at the University of Arizona’s Seward Observatory Mirror Lab, the only facility on Earth capable of creating such enormous mirrors. As with the other six mirrors that will comprise the GMT’s main optical surface, the third mirror will weigh approximately 20 tons and measure 27 feet in diameter.

The spin-casting process creates the essential paraboloid shape for the mirror; thanks to the spinning motion, a depression forms in the center of the casting medium as its outer edges rise up the walls of the furnace. In the case of the GMT mirrors, about 21 tons of borosilicate glass flow into a prefabricated mold to form the lightweight honeycomb structure of the mirror; this structure will be very stiff and allow the mirror to adjust rapidly to temperature fluctuations at night, preventing distortion of the images obtained. Once it is cast, the third mirror will be polished to an optical surface accuracy within approximately 25 nanometers.

The GMT’s optical systems will be the most sophisticated ever deployed. Light will reflect off the seven mirror segments of the primary mirror, again off the seven smaller secondary mirrors, and finally down through the central primary segment to the imaging cameras. The secondary mirrors are flexible, thanks to hundred of actuators under the surface of each, to counteract atmospheric turbulence and provide unprecedented resolution.

The GMT is a joint endeavor by institutions around the world, including Astronomy Australia Ltd., Australian National University, Carnegie Institution for Science, Harvard University, Korea Astronomy and Space Science Institute, Smithsonian Institution, University of Texas at Austin, Texas A&M University, University of Arizona, and University of Chicago.

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Former Pakistani President Pervez Musharraf is indicted

Former Pakistani President Pervez Musharraf was indicted on Tuesday in the 2007 assassination of Benazir Bhutto. According to CBS News, Pakistani television reports indicated that Musharraf was “charged with murder, conspiracy to commit murder and facilitating murder.”

The indictment was handed down in Rawalpindi, a city near the capital Islamabad and where Bhutto was killed in a bombing in December 2007 following a political rally.

Not long after the assassination, Musharraf said in an interview that he had warned Bhutto about the security threats she faced upon her return from exile. “I knew that she’s under threat. She herself knew that…There’s no real protection against a suicide bomber really.”

Bhutto was the first female prime minister of a Muslim country when she came to power in Pakistan in the late 1980s. She also served another term in the mid-1990s. General Musharraf overthrew the government of Prime Minister Nawaz Sharif in 1999, and when he instituted strict policies intended to keep both Bhutto and Sharif out of office, she went into exile.

Bhutto’s widower, Asif Ali Zardari, has been president of Pakistan since his election in 2008 after he took over as leader of his wife’s political party, the Pakistan People’s Party. Sharif is once again prime minister, meaning that Musharraf’s old rivals hold the two highest positions of power in Pakistan, although Zardari is slated to complete his term next month.

After being exiled since his removal from power in 2008, Musharraf returned to Pakistan earlier this year in an attempt to reenter politics, an effort that was stymied by the government.

But with relations between the civilian government and military ever tenuous, there is concern that the court’s move could potentially destabilize the country.

CBS’s report cited both a “Western diplomat” and a member of Sharif’s party as giving voice to the possibility that the former prime minister might be angling for revenge against the man who deposed him in 1999, which might cause renewed domestic conflict and, by extension, difficulties for the United States as it attempts to secure continued support of the Pakistani government in its counterterrorism operations.
Whatever the motivation, the indictment is a stark change for the country and its long history of deference to its military. The charges against the seventy-year-old Musharraf marked a first in Pakistan’s sixty-six year history: never before has a general once so powerful been charged with a crime.

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NASA image shows orbits of Potentially Hazardous Asteroids

NASA has compiled an evocative new image, PIA17041, showing the orbits of all known Potentially Hazardous Asteroids (PHAs). The image shows the Sun and the orbits of our solar system’s inner, rocky planets, Mercury, Venus, Earth, and Mars, relatively close to it. The outer boundary of the image is the concentric, but far more distant, orbit of Jupiter. Between the sun and the orbit of Jupiter, intermingled with the orbits of the rocky planets, are myriad more elliptical orbits of varying size.

These orbits are those of the 1,400 PHAs recorded as of early 2013. PHAs are considered hazardous because of their comparatively large sizes of at least 460 feet in diameter and their orbits’ proximity to that of Earth, within 4.7 million miles. However, simply being classified as a PHA does not mean that an asteroid is on a collision course with Earth; none of the PHAs shown in the image poses an actual threat to Earth within the next hundred years. Scientists will continue to track the PHAs and keep an eye out for undiscovered asteroids that might be a danger to Earth; with more data, the asteroids’ orbits can be refined and their future close flybys and impact probabilities can be calculated more precisely.

The image was released by NASA, the Jet Propulsion Laboratory, and Caltech on August 2.

In late June, NASA announced the discovery of the 10,000th near-Earth object (NEO), asteroid 2013 MZ5. NEOs’ orbits bring them to within 28 million miles of Earth, and they range in size from several feet to 25 miles across, in the case of 1036 Ganymede, the largest known NEO. It is estimated that, of the 10,000 known NEOs, 10 percent are more than six-tenths of a mile across and could cause global decimation if an impact with Earth occurs.

Asteroids are relics of the formation of our solar system 4.6 billion years ago. Most asteroids reside in the asteroid belt between the orbits of Mars and Jupiter. However, the effects of Jupiter’s tremendous gravity and occasional interactions with Mars can alter asteroids’ orbits and send them tumbling towards or away from the Sun. These errant asteroids become locked into highly elliptical orbits that take them across the orbits of the planets, as seen in the image PIA17041.

The majority of asteroids are not NEOs. The largest NEO is the aforementioned 1036 Ganymede, which is 25 miles across. The largest object in the asteroid belt is the dwarf planet Ceres, which is 592 miles in diameter. Ceres and the somewhat smaller, lumpier asteroid Vesta are considered to be failed planets, their early growth hindered by the formation of Jupiter. NASA’s Dawn mission, which launched in September 2007, will orbit and study Vesta and Ceres.

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Meteor plume across northern hemisphere tracked by NASA

On February 15, 2013, all eyes were on asteroid 2012 DA14 during its close approach to Earth. However, as 2012 DA14 sailed safely past our planet, an unrelated meteor on a totally different trajectory blazed through the atmosphere before exploding 14.5 miles above the Russian town of Chelyabinsk. This meteor was considerably smaller than 2012 DA14, measuring 59 feet across and weighing 11,000 metric tons.

The unnamed meteor approached Earth from a direction within 15 degrees of the direction of the sun, a region of the sky that cannot be monitored by asteroid detection telescopes. It struck the atmosphere above the Kazakhstan/Russia border and headed northwest into Russia. The fireball screamed through the sky at 11.6 miles per second. Thirteen seconds after entering the atmosphere, the meteor shattered as forces from in front of it, caused by compression and heating of atmospheric gases, and from behind it exceeded its tensile strength.

The meteor explosion released nearly 500 kilotons of energy. This tremendous force hurtled fragments of the meteor towards the ground, and also, according to a new NASA study, spread hundreds of tons of dust through the atmosphere.

The new study, led by Chelyabinsk native Nick Gorkavyi of NASA’s Goddard Space Flight Center, is the first space-based study of the evolution of a dust plume from a meteor. Gorkavyi and colleagues used data from the Ozone Mapping Profiling Suite Instrument’s Limb Profiler on the NASA-NOAA Suomi National Polar-orbiting Partnership satellite, combined with atmospheric models, to track and map the distribution of debris through the atmosphere in the hours and days after the meteor exploded.

About 3.5 hours after the explosion, the satellite detected a dust plume in the stratosphere, at an altitude of around 25 miles and moving east in the stratospheric jet stream at approximately 190 miles per hour.

One day after the explosion, the plume was still flowing eastward and had reached the Aleutian Islands. The larger, heavier grains began to lose altitude and speed, whereas the smaller, lighter particles continued their journey.

Four days after the explosion, those lighter particles that had remained aloft had wound their way entirely around the northern hemisphere and back to Chelyabinsk.

Three months after the explosion, the satellite could still discern a plume of dust encircling the northern hemisphere.

“In the space age, with all of this technology, we can achieve a very different level of understanding of injection and evolution of meteor dust in the atmosphere,” Gorkavyi explained. “Of course, the Chelyabinsk bolide is much smaller than the ‘dinosaurs killer,’ and this is good: we have the unique opportunity to safely study a potentially very dangerous type of event.”

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Petition to oust San Diego Mayor Bob Filner gains support

“Filner: Resign or Recall” was the rallying cry  Sunday during the Freedom From Filner March in San Diego, which kicked off efforts to have controversial mayor Bob Filner recalled. Organizers have until September 26th to get the 102,000 signatures they need.

To date 16 women have come forward and accused Mayor Filner of sexual misconduct. Several of appeared at the rally Sunday, along with high profile attorney Gloria Allred, who represents three of the accusers. Allred called for Filner’s removal from office, telling the crowd: “There is no excuse for abuse and there is no excuse for you to stay in power.”

Mayor Filner has refused to step down from office since returning early from a behavior-therapy program in July. All nine San Diego city council members and both U.S. Senators from California, Diane Feinstein and Barbara Boxer, have called for Mayor Filner to recall. He rebuked their request, however, saying that although he had “failed to fully respect the women who work for me and with me” he expects to be vindicated by “a full presentation of the facts”.

The recall effort kicked off Sunday at 12:01 am, with canvassers sweeping San Diego’s popular Gaslamp District for signatures. Although there is a long road ahead of them, organizers and supporters of the effort are determined to see the recall through to completion. “We’re going to be everywhere. We’re going to be at sporting events. We’re going to be at street fairs, arts shows — you name it, we will be out there,” Dave McCulloch, one of the recall organizers, said Sunday.

Although there were Filner supporters at the rally Sunday, the embattled mayor’s popularity has plummeted since the allegations came to light. In a recent local news poll 81% of respondents said they would like to see Mayor Filner out of office. Many at the rally Sunday admitted to voting for Filner when he was elected in 2012, but now regret their actions.

Peggy Shannon, a 67 year old great-grandmother, is the latest woman to accuse Mayor Filner of sexual harassment. She stood by Allred, her attorney, at the march, but did not speak to the crowd. She has accused the mayor of hugging and kissing her on the lips at work, as well as making a number of lewd comments.

Despite a lack of support from his fellow politicians and the public at large, Mayor Filner returned to work on Monday.