Not a Quirk But a Quark ... a Quark Star!

Super-luminous stellar explosion observed via Caltech's Palomar Observatory, possibly resulting in a quark star

Illustration of a supernova explosion.
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Astronomers recently announced that they have found a novel explanation for a rare type of super-luminous stellar explosion that may have produced a new type of object known as a quark star.

Three exceptionally luminous supernovae explosions have been observed in recent years. One of them was first observed using a robotic telescope at the California Institute of Technology's (Caltech) Palomar Observatory.

Data collected with Palomar's Samuel Oschin Telescope was transmitted from the remote mountain site in southern California to astronomers via the High-Performance Wireless Research and Education Network (HPWREN), funded by the National Science Foundation (NSF). The Nearby Supernova Factory research group at the Lawrence Berkeley Laboratory reported the co-discovery of the supernova, known as SN2005gj.

Researchers in Canada have analyzed this, along with two other supernovae, and believe that they each may be the signature of the explosive conversion of a neutron star into a quark star.

These three supernovae, each 100 times brighter than a typical supernova, have been difficult to explain. The Canadian research team thinks the explosions herald the creation of a previously unobserved and new class of objects, designated as quark stars.

A quark star is a hypothetical type of star composed of ultra dense quark matter. Quarks are the fundamental components of protons and neutrons, which make up the nucleus of atoms. The most dense objects known to exist today are neutron stars--stars composed entirely of tightly packed neutrons. A typical neutron star is some 16 miles across, yet has a mass one and a half times the mass of our Sun.

Neutron stars are formed when a massive star undergoes a supernova explosion at the end of its life. The question is, is a neutron star indeed the most dense object that exists? It is thought that if the neutrons are too tightly packed--if what scientists consider a neutron star is too dense--the resulting instability may lead to a further collapse, resulting in a second explosion and the creation of a quark star. The energy that powers that second explosion comes from neutrons breaking down into their component parts: quarks.

Further observations should help to confirm or defeat the hypothesis of quark stars, but in either case, the use of a high-speed network like HPWREN helps astronomers across the world explore the frontiers of science.

About HPWREN

HPWREN is an NSF-funded network research project, which also functions as a collaborative cyberinfrastructure on research, education and first responder activities. It includes creating, demonstrating and evaluating a non-commercial, prototype, high-performance, wide-area, wireless network in San Diego, Riverside and Imperial counties in California. The network includes backbone nodes at the University of California, San Diego, and San Diego State University campuses, and a number of "hard to reach" areas in remote environments.

Caltech's Palomar Observatory and the nearby Supernova Factory Research Group at the Lawrence Berkeley Laboratory have also been supported in part by NSF.

--	Lisa-Joy Zgorski, (703) 292-8311 lisajoy@nsf.gov

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Citizen Astronomy

By Janet Raloff

Voorwerp's DiscovererA month after Galaxy Zoo got started, this primary-school teacher had already discovered what may be a totally novel type of celestial object. Edd Edmondson

When a small band of astronomers launched Galaxy Zoo almost a year ago, they didn’t know what to expect. They had a boatload of photos (scientific translation: roughly 1 million) depicting never-before-seen patches of the sky. These researchers and their colleagues lacked the time and stamina to sequentially sift through the images, one by one, classifying the galaxies they showed.

In theory, computers could have been tasked with screening those photos. But image-processing software doesn’t yet hold a candle to our brains’ accuracy at evaluating whether shapes match — or don’t — the samples they’ve been trained to compare.

So the researchers took a gamble. Not a terribly expensive one. But there was, theoretically, science on the line.

They loaded all of the images onto a computer along with a little training session and then, last July, invited all comers to log on and characterize the types of galaxies present in a randomly selected series of photographs that the site served up. All had been taken as part of the Sloan Digital Sky Survey.

From a scientific standpoint, Galaxy Zoo started paying dividends almost from day one. “This is not something we expected,” notes Chris Lintott, an Oxford University scientist and “zookeeper.” The hope was that hundreds of people would log on. To date, almost 150,000 have.

And the idea that many of the images might one day be categorized illustrates how low the zookeepers’ expectations had been. On average, each of the images on the site has already been seen and characterized by 50 people. Those 50 million photo evaluations “is simply fantastic,” Lintott says, “and illustrates for us one of the huge advantages of getting the public involved. It gives us an error bar on the classifications.”

Even if the world’s best characterizer was cataloging a million galaxies, there’s no way to evaluate whether he or she got sloppy mid-way through. You’d either have to accept the individual’s assessment or not. “Here we have multiple independent classifications,” Lintott observes. And by essentially averaging their assessments — and, potentially identifying outliers — the experts can tabulate the viewers’ apparent reliability. In fact, if there’s no clear consensus, that may itself point to something the experts need to see for themselves.

Moreover, Lintott observes, “We soon realized the public is very good at finding weird things.”

One of the first to emerge — now known as Hanny’s Voorwerp — may be the only known celestial object of its kind in the universe. Lintott will be the lead author of a research paper that formally announces the weird object’s discovery. He expects to submit it next week for publication in the Monthly Notices of the Royal Astronomical Society. This journal, which neither comes out monthly nor runs notices of the RAS, is the leading British site for astronomical publishing.

To show how much he and his colleagues value the nonscientist who first brought the object to their attention (a Dutch primary school teacher named Hanny van Arkel), they will make her a co-author on their paper.

The Voorwerp was hardly the only oddity zoogoers identified. “We’ve now collected a long list of weird things,” Lintott says. Some are objects that appear to be so-called gravitational lenses. “And we have this wonderful object called the blue banana.” He acknowledges having “no idea what it is yet. So at some point I’ve got to spend a few days trying to find out.”

But that’s when he gets a spare moment. Besides having full-time jobs, Lintott and the other zookeepers have been scurrying around at a furious pace to make use of the steady stream of data being served up by the public zoogoers. “We’ve already submitted four papers to the journals based on Galaxy Zoo data,” Lintott told me last night, “and there are about 25 separate research projects underway” based on GZ assessments.

So successful was Galaxy Zoo, that its developers will shortly roll out Galaxy Zoo Two. It will “ask the public to make more detailed classifications than we have before of the brightest quarter-of-a-million galaxies or so,” Lintott says. And the new zoo will make it easier to identify the more unusual objects. Viewers can simply tag images they think deserve professional follow-up.

The best thing about this is that it engages the public in science and lets former outsiders experience not only the wonder of discovery but an ability to interact online with scientists and fellow enthusiasts. Actually, it sounds a lot like being a Science News reporter.

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Big haul of Crohn's genes shows disease complexity

By Ben Hirschler

LONDON (Reuters) - Scientists have linked 32 genetic variations to Crohn's disease, a bowel disorder, highlighting the complexity of many common diseases and the difficulties facing researchers seeking treatments.

Scientists said on Sunday that new research had tripled the number of genetic regions implicated in Crohn's, the most common form of inflammatory bowel disease, and many more were probably still undiscovered.

"These explain only about a fifth of the genetic risk, which implies that there may be hundreds of genes implicated in the disease, each increasing susceptibility by a small amount," said Jeffrey Barrett from the Wellcome Trust Centre for Human Genetics at the University of Oxford, who led the research.

Scientists have known for years that genes, along with environmental factors, play a role in increasing the risk that people will develop many common problems like asthma, high blood pressure, rheumatoid arthritis, cancer and heart disease.

But they are still trying to work out which parts of the genome -- the 3 billion sub-units of DNA in our cells -- are actually responsible.

One way to find out is to conduct genome-wide association studies, in which genetic markers from thousands of volunteers are analyzed in order to identify genetic differences between diseased and healthy individuals.

The latest picture to emerge for Crohn's, which was reported in the journal Nature Genetics, represents the most complete picture yet assembled of the genetic influences on risk of a common disease.

Significantly, three of the individual genes that have been implicated in Crohn's have previously been shown to influence risk of type 1 diabetes and asthma, suggesting a possible common genetic mechanism underlying these disorders.

Crohn's disease affects between one in 500 and one in 1000 people in the industrialized world, causing inflammation, pain, ulcers and diarrhea.

Modern biotech drugs like Abbott Laboratories's Humira, UCB's Cimzia and Johnson & Johnson's Remicade can help, but many patients end up needing surgery.

By pinpointing genes linked to the condition, researchers hope to find fresh targets for new drugs.

One of the most promising is thought to be the CCR6 gene, which is believed to be part of the signaling machinery that causes white blood cells in the gut to become over-active, leading to inflammation.

The same white blood cells are also present in inflamed joints, implying that CCR6 may play a role in rheumatoid arthritis as well, making it of added interest to the pharmaceutical industry, Barrett and colleagues said.

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