Science News

Quirky Pulsar System Challenges Theories of Binary Formation; Observing Stem Cells at Work; Large scale carbon sequestration

Quirky Pulsar System Challenges Theories of Binary Formation
From a Cornell Press Release:

An ongoing sky survey using the Cornell-managed Arecibo radio telescope in Puerto Rico has turned up a massive, fast-spinning binary pulsar with a mysterious elongated orbit, researchers say.

The pulsar and its companion star challenge currently accepted views of binary pulsar formation and give researchers a new opportunity for understanding the fundamental properties of highly dense matter.

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A comparison of the orbits of the pulsar J1903+0327 and its possible sun-like companion star with the orbit of the Earth around the sun. The objects’ sizes are not to scale. (Bill Saxton, NRAO/AUI/NSF)
The pair of objects is quirky in several ways, said Jim Cordes, professor of astronomy at Cornell and one of the paper’s authors. The pulsar, JI903+0327, rotates once every 2.15 milliseconds, making it one of the faster-spinning among the known millisecond pulsars, or MSPs (pulsars that rotate once every 10 milliseconds or faster).

While about 50 MSPs have been identified in our galaxy, Cordes said, other MSPs in binary systems orbit in tight, precise circles. The JI903+0327 system’s orbit, by contrast, is highly eccentric.

“These are [usually] the most perfect circles in the universe,” said Cordes. “When we come across an object that has high eccentricity, it really stands out. We don’t know of any other MSP like this.”

The companion star itself is another anomaly: Apparently, it is a main sequence star (similar to our sun) rather than the more typical white dwarf or neutron star.

According to conventional scenarios for binary pulsar evolution, pulsars with slower spins are either isolated or, if in a binary, are likely to have been knocked into an eccentric orbit by the explosion of the supernova that created the pulsar. Faster spinning MSPs, on the other hand, have usually been “spun up” by momentum and matter accreted by their companion star’s precursor — and orbit in near-perfect circles.

Taken together, the newly discovered pulsar’s fast spin, eccentric orbit and unusual companion require an alternate explanation — possibly involving interaction with a third object or recent ejection from a globular cluster.

“In a globular cluster you’ve got all these other things happening — collisions, other interactions … that provide numerous pathways for formation,” Cordes said.

Meanwhile, the pulsar’s high mass (1.74 solar masses) could help physicists better understand how matter behaves in extreme conditions.

(More at Cornell)


Observing Stem Cells at Work

From a Fraunhofer-Gesellschaft Press Release:

Stem cells can differentiate into 220 different types of body cell. The development of these cells can now be systematically observed and investigated with the aid of two new machines that imitate the conditions in the human body with unprecedented accuracy.

Stem cells are extremely versatile: They can develop in 220 different ways, transforming themselves into a correspondingly diverse range of specialized body cells. Biologists and medical scientists plan to make use of this differentiation ability to selectively harvest cardiac, skin or nerve cells for the treatment of different diseases. However, the stem cell culture techniques practiced today are not very efficient. What proportion of a mass of stem cells is transformed into which body cells? And in what conditions? “We need devices that keep doing the same thing and thus deliver statistically reliable data,” says Professor G√ľnter Fuhr, director of the Fraunhofer Institute for Biomedical Engineering IBMT in St. Ingbert.

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Two prototypes of laboratory devices for stem cell differentiation enable the complex careers of stem cells to be systematically examined for the first time ever. These devices are the result of the international project ‘CellPROM’ – ‘Cell Programming by Nanoscaled Devices’ – which was funded by the European Union to the tune of 16.7 million euros and coordinated by the IBMT. “The type of cell culture used until now is too far removed from the natural situation,” says CellPROM project coordinator Daniel Schmitt – for in the body, the stem cells come into contact with solute nutrients, messenger RNAs and a large number of different cells. Millions of proteins rest in or on the cell membranes and excite the stem cells to transform themselves into specialized cells. “We want to provide the stem cells in the laboratory with a surface that is as similar as possible to the cell membranes,” explains Daniel Schmitt. “To this end, the consortium developed a variety of methods by which different biomolecules can be efficiently applied to cell-compatible surfaces.”

In the two machines – MagnaLab and NazcaLab – the stem cells are brought into contact with the signal factors in a pre-defined manner. In MagnaLab, several hundred cells grow on culture substrates that are coated with biomolecules. In NazcaLab, large numbers of individual cells, washed around by a nutrient solution, float along parallel channels where they encounter micro-particles that are charged with signal factors. “We use a microscope and a camera to document in fast motion how individual cells divide and differentiate,” says Schmitt. The researchers demonstrated on about 20 different cell models that the multi-talents can be stimulated by surface signals to transform themselves into specialized cells.

Large scale carbon sequestration

From Indiana University:

Indiana Geological Survey scientists at Indiana University will participate in a new $67 million U.S. Department of Energy project to test the feasibility of storing carbon dioxide at underground sites in Ohio and Indiana.

The evaluations are being carried out with the Midwest Regional Carbon Sequestration Partnership, a research consortium of government, academy and industry researchers led by Columbus, Ohio-based Battelle Memorial Laboratories.

One million metric tons of carbon dioxide, a greenhouse gas, will be diverted from a Greenville, Ohio, ethanol production facility for use in the study. The gas will be pressurized at the site and injected 3,000 feet underground into a saltwater-filled geological formation called the Mount Simon Sandstone. Scientists will evaluate the ability of the rock to securely contain the injected carbon dioxide. The sandstone is capped by a extensive layer of dense shale that prevents the relatively light carbon dioxide from escaping upward. Scientists also plan to evaluate the area surrounding a Duke Energy Corporation gasification power plant now being constructed at Edwardsport, Ind.

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In the middle of this diagram created by U.S. Geological Survey staff, carbon dioxide is routed from its emissions source (a power plant) to various storage “reservoirs” underground. The current DOE project will look at the storage of carbon dioxide in a 3,000-foot-deep saline aquifer. (Indiana University)

“As experts on the regional geology, the Indiana Geological Survey will support Battelle’s overall evaluation of the sequestration technology by providing detailed information about the character of the reservoir rock as well as the seal,” said John A. Rupp, assistant director of research for the survey, an Indiana University research institute.

The evaluation, injection and monitoring of carbon sequestration at the Ohio site will take approximately 10 years. This latest project is actually Phase III of the U.S. Department of Energy’s efforts to determine whether carbon sequestration is an effective approach toward reducing anthropogenic (human-caused) carbon dioxide emissions. Phases I and II determined the location of possible carbon dioxide reservoirs and examined how some of those reservoirs handled small-scale injections of carbon dioxide, up to 10,000 metric tons. Six Phase III tests have been funded at various localities around the nation; each will evaluate large-scale — one million tons — storage of injected carbon dioxide.

Rupp says carbon sequestration is only part of the solution to humanity’s greenhouse gas problem.

“Large fossil fuel-burning facilities can generate tens of millions of tons of carbon dioxide per year,” he said. “If we want to reduce anthropogenic emissions using carbon sequestration, we will have to deploy this technology on a massive scale. Ultimately we’ll need to include other ways of reducing emissions.”