Hubble Sees Messier 70: Tight and Bright

In this image, the NASA/ESA Hubble Space Telescope has captured the brilliance of the compact center of Messier 70, a globular cluster. Quarters are always tight in globular clusters, where the mutual hold of gravity binds together hundreds of thousands of stars in a small region of space. Having this many shining stars piled on top of one another from our perspective makes globular clusters a popular target for amateur skywatchers and scientists alike.

Messier 70 offers a special case because it has undergone what is known as a core collapse. In these clusters, even more stars squeeze into the object's core than on average, such that the brightness of the cluster increases steadily towards its center.

The legions of stars in a globular cluster orbit about a shared center of gravity. Some stars maintain relatively circular orbits, while others loop out into the cluster's fringes. As the stars interact with each other over time, lighter stars tend to pick up speed and migrate out toward the cluster's edges, while the heavier stars slow and congregate in orbits toward the center. This huddling effect produces the denser, brighter centers characteristic of core-collapsed clusters. About a fifth of the more than 150 globular clusters in the Milky Way have undergone a core collapse.

Although many globular clusters call the galaxy's edges home, Messier 70 orbits close to the Milky Way's center, around 30 000 light-years away from the Solar System. It is remarkable that Messier 70 has held together so well, given the strong gravitational pull of the Milky Way's hub.

Messier 70 is only about 68 light-years in diameter and can be seen, albeit very faintly, with binoculars in dark skies in the constellation of Sagittarius (The Archer). French astronomer Charles Messier documented the object in 1780 as the seventieth entry in his famous astronomical catalogue.

This picture was obtained with the Wide Field Camera of Hubble’s Advanced Camera for Surveys. The field of view is around 3.3 by 3.3 arcminutes. 

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Nasa struggles even as its science missions bring universe into sharper focus

Life is tough these days at NASA, the space agency that can’t launch anyone into space.

It wrestles with basic questions: Where to go? How to get there? When? And for what purpose?

It killed a plan to return to the moon and now is building a jumbo rocket to go to ... well, it’s unclear. Maybe to an asteroid: a rock to be named later.

NASA is betting that private companies will create a commercial taxi for flights to low Earth orbit. In the meantime, NASA astronauts ride on aging Russian rockets that look increasingly creaky. At any given moment, a few Americans are on the international space station, circling the planet every 90 minutes, nearly as anonymous as they are weightless.

But even as NASA goes through this awkward transition in human space flight, the agency has one bright spot: science. NASA’s scientific missions — robotic probes, telescopes, satellites — are bringing Earth, the sun, the solar system and the universe into sharper focus.

Science at NASA is not without serious problems, a fact expected to be reflected in the Obama administration’s budget request Monday.

The James Webb Space Telescope, the successor to the Hubble, has gone far over budget and is still years from launch. The next Mars rover has also experienced cost overruns. As a result, planetary science, one of the divisions within NASA’s science directorate, will suffer a sharp cut under the new Obama budget, according to scientists familiar with the administration’s plans. Scientists expect that NASA will terminate its collaboration on two European-led robotic Mars missions scheduled for later this decade.

The question is: To what extent will future science missions be squeezed, delayed or terminated by the NASA budget crunch? What’s certain is that NASA has managed in recent years to launch a formidable fleet of scientific instruments.

NASA’s internal chart shows 86 missions, involving 96 spacecraft, either in service or preparation. That doesn’t include the two European Mars missions. It does include other international collaborations, and the extended operations of aging spacecraft that have completed their primary mission and are still blinking away.

One probe, New Horizons, is on its way to Pluto. Another, Messenger, has been orbiting Mercury since March. A lunar orbiter launched in 2009 has mapped the moon in unprecedented detail, and two more NASA spacecraft achieved lunar orbit six weeks ago on a mission to study the moon’s gravitational field and interior structure.

NASA’s Juno spacecraft blasted off in August on a five-year mission to Jupiter. The robotic probe Cassini continues to study Saturn, and in a week will make another close pass of the huge moon Titan.

Kepler, a space telescope launched in 2009, has found 61 planets by last count, with many more candidate planets yet to be confirmed. The longer Kepler observes a small patch of deep space, the more likely it is that it will detect a true Earth twin — a planet that’s both Earth-size and in a propitious orbit that puts it in a star’s “habitable zone.”

NASA is eager to see what happens on the morning of Aug. 6, when the $2.5 billion Mars Science Laboratory, launched in November, lands in a crater and dispatches a souped-up rover, Curiosity, to look for signs that Mars was once warm, wet and teeming with Martian life. The laboratory will land on Mars using a never-before-deployed technology called a sky crane.

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NASA’s Hubble Space Telescope Solves Mystery on Source of Supernova in Nearby Galaxy

Baltimore, MD – Using NASA’s Hubble Space Telescope, astronomers have solved a longstanding mystery on the type of star, or so-called progenitor, which caused a supernova seen in a nearby galaxy. The finding yields new observational data for pinpointing one of several scenarios that trigger such outbursts.

Based on previous observations from ground-based telescopes, astronomers knew the supernova class, called a Type Ia, created a remnant named SNR 0509-67.5, which lies 170,000 light-years away in the Large Magellanic Cloud galaxy.

Theoretically, this kind of supernova explosion is caused by a star spilling material onto a white dwarf companion, the compact remnant of a normal star, until it sets off one of the most powerful explosions in the universe.

Astronomers failed to find any remnant of the companion star, however, and concluded that the common scenario did not apply in this case, although it is still a viable theory for other Type Ia supernovae.

“We know Hubble has the sensitivity necessary to detect the faintest white dwarf remnants that could have caused such explosions,” said lead investigator Bradley Schaefer of Louisiana State University (LSU) in Baton Rouge. “The logic here is the same as the famous quote from Sherlock Holmes: ‘when you have eliminated the impossible, whatever remains, however improbable, must be the truth.’”

The cause of SNR 0509-67.5 can be explained best by two tightly orbiting white dwarf stars spiraling closer and closer until they collided and exploded.

For four decades, the search for Type Ia supernovae progenitors has been a key question in astrophysics. The problem has taken on special importance during the last decade with Type Ia supernovae being the premier tools for measuring the accelerating universe.

Type Ia supernovae release tremendous energy, in which the light produced is often brighter than an entire galaxy of stars. The problem has been to identify the type of star system that pushes the white dwarf’s mass over the edge and triggers this type of explosion. Many possibilities have been suggested, but most require that a companion star near the exploding white dwarf be left behind after the explosion.

Therefore, a possible way to distinguish between the various progenitor models has been to look deep in the center of an old supernova remnant to search for the ex-companion star.

In 2010, Schaefer and Ashley Pagnotta of LSU were preparing a proposal to look for any faint ex-companion stars in the center of four supernova remnants in the Large Magellanic Cloud when they discovered the Hubble Space Telescope already had taken the desired image of one of their target remnants, SNR 0509-67.5, for the Hubble Heritage program, which collects images of especially photogenic astronomical targets.

In analyzing the central region, they found it to be completely empty of stars down to the limit of the faintest objects Hubble can detect in the photos. Schaefer suggests the best explanation left is the so-called “double degenerate model” in which two white dwarfs collide.

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NASA forces Apollo astronaut to give back space camera

Former astronaut Edgar Mitchell has reluctantly given back the space camera he brought home from his 1971 Apollo 14 moon mission, rather than face a federal lawsuit over its ownership.

The 81-year-old argued the data acquisition camera was a gift from NASA, and earlier this year - four decades after taking it to space - he tried to auction it through the British firm Bonhams.

NASA says the camera is U.S. government property and sued Mr Mitchell to get it back after learning in March the device was up for sale.

In papers filed Thursday, the U.S. Attorney’s Office in Miami stated Mr Mitchell, the sixth man to walk on the moon, will 'relinquish all claims of ownership, legal title, or dominion' of the 16mm motion picture camera.

Mr Mitchell agreed to allow Bonhams' New York auction house, where the camera was consigned for sale last June, to release the artifact to the government. Bonhams had estimated the camera's value at $60,000 to $80,000.

Once returned to NASA, the space agency will pass it on to the National Air and Space Museum in Washington for display within 60 days.

Both sides will pay their own legal expenses. A judge was expected to sign off on the settlement in the coming days.

Mitchell’s attorney Armen R. Vartian said his client decided the settlement was the best way to resolve a conflict with NASA.

'I think both sides saw the lawsuit as something that should not continue,' he added.

Mr Mitchell is one of 12 humans to have walked on the moon. He later received the Presidential Medal of Freedom.

The data acquisition cameras (DAC), measuring six inches, by four inches by two inches, were taken into space to record engineering data and lunar surface imagery.

This particular camera was one of two that went to the moon's surface on the Apollo 14 mission, which Mr Mitchell piloted. It shot the final five minutes of the lunar module, named Antares, landing on the moon.

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