Tag: Kelly

NASA’s Orion Engineer Admits They Can’t Get Past Van Allen Radiation Belts

‘If this does not get the skeptics going wild on the moon debate, we don’t know what will.In the video presentation above, NASA engineer Kelly Smith explains about many of the risks and pitfalls surrounding the new Orion Deep Space Mission to the planet Mars.Surprisingly, chief among Kelly’s concerns is whether or not his spacecraft can successfully pass through the perilous Van Allen Radiation Belts. Such is the prospective danger in fact, that NASA will have to [...]

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Warp in spacetime lets astronomers watch the same star explode four times



Excerpt from csmonitor.com

Thanks to a phenomenon known as gravitational lensing, the Hubble Space Telescope has captured four images of the same supernova explosion.

For the first time, a cosmic magnifying glass has allowed scientists to see the same star explosion four times, possibly offering a revealing glimpse into these explosive stellar deaths and the nature of the accelerating universe.

Astronomers using the Hubble Space Telescope have captured four images of a supernova explosion in deep space thanks to a galaxy located between Earth and the massive star explosion. You can see how Hubble saw the supernova in this NASA video. The galaxy cluster warped the fabric of space and time around it — like a bowling ball placed on a bed sheet — allowing scientists to see the supernova in four images.

"It was predicted 50 years ago that a supernova could be gravitationally lensed like this, but it's taken a long time for someone to find an example," lead study author Patrick Kelly, an astronomer at the University of California, Berkeley told Space.com. "It's fun to have been able to find the first one." 

The supernova, which was discovered on Nov. 11, 2014, is located about 9.3 billion light-years away from Earth, near the edge of the observable universe. The researchers have named the distant supernova SN Refsdal in honor of the late Norwegian astrophysicist Sjur Refsdal, a pioneer of gravitational lensing studies. Due to gravitational lensing, "the supernova appears 20 times brighter than its normal brightness," study co-author Jens Hjorth, head of the Dark Cosmology Centre at the Niels Bohr Institute at the University of Copenhagen, said in a statement.
The lensing galaxy, which is about 5 billion light-years from Earth, is part of a large cluster of galaxies known MACS J1149.6+2223. In 2009, astronomers discovered that this cluster was the source of the largest known image of a spiral galaxy ever seen through a gravitational lens.

The four images of the supernova each appeared separately over the course of a few weeks. This is because light can take various paths around and through a gravitational lens, arriving at Earth at different times.

Using gravity as a lens

Gravity is created when matter warps the fabric of reality. The greater the mass of an object, the more space-time curves around that object and the stronger its gravitational pull, the discovery enshrined in Einstein's theory of general relativity, which celebrates its centennial this year.

As a result, gravity can also bend light like a lens, meaning objects see n behind powerful gravitational fields, such as those of massive galaxies, are magnified. Gravitational lensing was first discovered in 1979, and today gravitational lenses can help astronomers see features otherwise too distant and faint to detect with even the largest telescopes.

"These gravitational lenses are like a natural magnifying glass. It's like having a much bigger telescope," Kelly said in a statement. "We can get magnifications of up to 100 times by looking through these galaxy clusters."

When light is far from a gravitationally lensing mass, or if the gravitationally lensing mass is not especially large, only "weak lensing" occurs, barely distorting the light. However, when the light comes from almost exactly behind the gravitationally lensing mass, "strong lensing" can happen. 

When a strongly lensed object occupies a large patch of space — for instance, if it's a galaxy — it can get smeared into an "Einstein ring" surrounding a gravitationally lensing mass. However, strong lensing of small, pointlike items — for instance, super-bright objects known as quasars — often produces multiple images surrounding the gravitationally lensing mass, resulting in a so-called "Einstein cross."

The observations of SN Refsdal mark the first time astronomers on Earth have witnessed strong lensing of a  supernova, with four images of an exploding star arrayed as an Einstein cross.

An expanding universe

These new findings could help scientists measure the accelerating rate at which the universe is expanding, researchers say.

A computer model of the lensing cluster suggests the scientists missed chances to see the lensed supernova 50 and 10 years ago. However, the model also suggests more images of the explosion will repeat again within the next 10 years.

The timing of when all these images of the supernova arrive depends on the gravitational pull of the matter generating the gravitational lens. So, by measuring those times, the researchers hope to map how visible normal matter and invisible dark matter is distributed in the lensing galaxy.

Dark matter is currently one of the greatest mysteries in science, a poorly understood substance thought to make up five-sixths of all matter in the universe. A better understanding of how dark matter is behaving in this gravitationally lensing cluster might help shed light on the material's nature, Kelly said.

Analyzing when the images arrive could also help scientists pinpoint the rate at which the universe is expanding. Although there are already several ways to measure the cosmic expansion rate, "there has been a lot of heated debate between different methods, so it'd be interesting to see how this new technique might affect the area," Kelly said. "It's always nice to have completely independent measurements of the same quantity."

The scientists detailed their findings in the March 6 issue of the journal Science.

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Hubble’s ‘Einstein Cross’ Marks the Space-Warping Spot


Image: Einstein Cross revealed
Flash from the supernova's blast has been warped into four points of light surrounding an elliptical galaxy in a cluster called MACS J1149.2+2223, which is 5 billion light-years away in the constellation Leo.


Excerpt from nbcnews.com
By Alan Boyle


One hundred years after Albert Einstein published his theory of general relativity, the Hubble Space Telescope has provided a demonstration of the theory at work: a picture of a distant galaxy so massive that its gravitational field is bending the light from an even more distant supernova. 

The image, released Thursday, shows how the flash from the supernova's blast has been warped into four points of light surrounding an elliptical galaxy in a cluster called MACS J1149.2+2223, which is 5 billion light-years away in the constellation Leo. 

"It really threw me for a loop when I spotted the four images surrounding the galaxy," Patrick Kelly, an astronomer from the University of California at Berkeley, said in a news release. "It was a complete surprise." 

Maybe it shouldn't have been. The configuration is known as an Einstein Cross. It's a well-known but rarely seen effect of gravitational lensing, which is in line with Einstein's assertion that a massive object warps the fabric of space-time — and thus warps the path taken by light rays around the object. 

In this case, the light rays are coming from a stellar explosion that's directly behind the galaxy, but 4.3 million light-years more distant. Computer models suggest that the four-pointed cross will eventually fade away, to be followed within the next five years by the reappearance of the supernova's flash as a single image. 

Kelly is part of a research collaboration known as the Grism Lens Amplified Survey from Space, or GLASS. The collaboration is working with the Frontier Field Supernova team, or FrontierSN, to analyze the exploding star. He's also the lead author of a paper on the phenomenon that's being published this week by the journal Science as part of a package marking the 100th anniversary of Einstein's general relativity theory. 

The researchers suggest that a high-resolution analysis of the gravitational lensing effect can lead to better measurements of cosmic distances and galactic masses, including the contribution from dark matter. The Hubble team says the faraway supernova has been named "Refsdal" in honor of Norwegian astronomer Sjur Refsdal, who proposed using time-delayed images from a lensed supernova to study the expansion of the universe. 

"Astronomers have been looking to find one ever since," UCLA astronomer Tommaso Treu, the GLASS project's principal investigator, said in Thursday's news release. "The long wait is over!" 

The Einstein Cross is the subject of a Google+ Hangout at 3 p.m. ET Thursday, presented by the Hubble science team. You can watch the event now or later via YouTube. Check out a preprint version of the Science report.

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Whose messages are you listening to?

a message from Cheryl Richardson

Monday, 21 June, 2010  (posted 22 June, 2010)

New Rules

This morning I visited our farmer’s market to get some fresh vegetables and to see what kinds of ...

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