Physical sciences news, 12/24/07 - 12/30/07

High-energy galactic objects

Objects in our galaxy that are capable of generating hard X-rays or the even higher-energy gamma-rays are quite unusual, and therefore of significant scientific interest. A European ground-based observatory known as H. E. S. S. (High Energy Stereoscopic System) is capable of indirectly detecting TeV gamma-rays. One of the sources it has found, designated as HESS J1837-069, has also been detected by the Japanese Suzaku satellite X-ray observatory, and is suspected to be what is called a "pulsar wind nebula". A similar object, HESS J1614-518, which is the brightest extended TeV gamma-ray source discovered in the H. E. S. S. galactic plane survey, has also been observed as a weak X-ray source by Suzaku.

• Mysterious Cosmic Powerhouses Explored
• Discovery of Extended X-Ray emission from the unidentified TeV source HESS J1614-518 using the Suzaku Satellite
• The INTEGRAL - HESS/MAGIC connection: a new class of cosmic high energy accelerators from keV to TeV

X-rays from rotating radio transients

Compact objects first known only by periodic short bursts of radio-frequency photons have been suspected to be rotating neutron stars and are called "rotating radio transients". Periodic X-ray bursts occurring much more frequently from one such object (J1819-1458) have been detected by the XMM-Newton satellite X-ray observatory, and they support the identification of the object as a neutron star.

• XMM-Newton Detects Pulsed Heartbeat Of A Weird New Type Of Star
• Pulsed Heartbeat Star
• Discovery of Pulsations and a Possible Spectral Feature in the X-ray Emission from Rotating Radio Transient J1819-1458

Star formation

Yet another illustration of the value of observing astronomical objects in diverse portions of the spectrum comes from studies of a protostar known as HH-211. Radio-frequency observations show jets of matter emerging from the poles of the rotating protostar, while infrared observations show emissions from shocked molecular hydrogen in a region of gas surrounding the jets. The observations support the hypothesis that the jets carry off angular momentum, allowing gradual growth of the protostar.

• Jets Are a Real Drag
• Jets Spiral in 'Reverse Whirlpool' from Star
• Submillimeter arcsecond-resolution mapping of the highly collimated protostellar jet HH 211

Extrasolar planets

The existence of most extrasolar planets detected so far has been deduced indirectly from perturbations in the movement of its parent star. But extrasolar planet HD 189733b has proven to be one of the most amenable extrasolar planets to direct observation. (For example, here.) Now it has actually been observed by reflected light from the stellar parent.

• Polarization technique focuses limelight
• Studying Planets With Sunglasses
• First Reflected Light from an Exoplanet?

Nanoparticle medicine

In the last year or so there has been quite a flood of reports of the use of nanoparticles as medical diagnostic tools or mechanisms for combating cancer and infectious diseases by heating or delivery of drugs. The past week has brought two more examples, involving gold nanoparticles. In one example the nanoparticles bind specifically to tumor cells, where they can be observed using laser illumination. In a second example the nanoparticles bind to the parasite responsible for toxoplasmosis. The parasite is destroyed when the nanoparticles are heated using suitable illumination from a laser.

• Gold Nanoparticle Probes May Allow Earlier Cancer Detection
• 'Golden Bullet' Shows Promise For Killing Common Parasite