Physics & Astronomy News

<p>Artist rendering<br />
New radiation source could be less harmful alternative to x-rays
A new source of intense terahertz (THz) radiation, which could offer a less harmful alternative to x-rays and has strong potential for use in industry, is being developed.
<p>Though Mercury may look drab to the human eye, different minerals appear in a rainbow of colors in this image from NASA's MESSENGER spacecraft. (Image credit: NASA/Johns Hopkins University APL/Carnegie Institution of Washington)</p>
Mercury May Have a Thinner Crust Than We Thought
Scientists used careful mathematical calculations to determine the density of Mercury’s crust, which is thinner than anyone thought.

<p>An artistic view of frequency conversion from near-infrared to mid-infrared through a nonlinear crystal. (Photo: Alexander Gelin)</p>
Molecules Brilliantly Illuminated
A new high-power laser system generates ultrashort pulses of light covering a large share of the mid-infrared spectrum.
<p>A cloud of atoms is held above a chip by electromagnetic fields. The EPR paradox was observed between the spatially separated regions A and B (Illustration: University of Basel, Department of Physics)</p>
EPR paradox observed in many-particle system for the first time
Physicists have observed the quantum mechanical Einstein-Podolsky-Rosen paradox in a system of several hundred interacting atoms for the first time.

Einstein’s “spooky action” goes massive!
The elusive quantum mechanical phenomenon called entanglement has now been made a reality in objects almost macroscopic in size.
Organic solar cells reach record efficiency
In an advance that makes a more flexible, inexpensive type of solar cell commercially viable, researchers have demonstrated organic solar cells that can achieve 15% efficiency.
New exotic phenomena seen in photonic crystals
Researchers observe, for the first time, topological effects unique to an 'open' system.

Science Facts

Big Fish

by Gene Mascoli and

Hubble Space Telescope in orbit as seen from the Space Shuttle.: Image Courtesy NASA, STScI The phrase 'big fish eat little fish' may hold true when it comes to planets and stars. Perhaps as many as 100 million of the sun-like stars in our galaxy harbor close-orbiting gas giant planets like Jupiter, or stillborn stars known as brown dwarfs, which are doomed to be gobbled up by their parent stars. Space Telescope Science Institute astronomer Mario Livio and postdoctoral fellow Lionel Siess did not directly observe the planets, because they had already been swallowed by their parent stars. But Livio did find significant telltale evidence that some giant stars once possessed giant planets that were then swallowed up. The devouring stars release excessive amounts of infrared light, spin rapidly, and are polluted with the element lithium.

About 4 to 8 percent of the stars in our galaxy display these characteristics, according to Livio and Siess. This is consistent with estimates of close orbiting giant planets, based on discoveries of extrasolar planets by radial velocity observations, which measure the amount of wobble in a star due to the gravitational tug of an unseen companion. An aging solar-type star will expand to a red giant and in the process engulf any close-orbiting planets. If the planets are the mass of Jupiter, or greater, they will have a profound effect on the red giant's evolution. First, according to Livio's calculations, such a star is bigger and brighter because it absorbs gravitational energy from the orbiting companion. This heats the star so that it puffs off expanding shells of dust, which radiate excessive amounts of infrared light.

The orbiting planet also transfers angular momentum to the star, causing it to 'spin up' to a much faster rate than it would normally have. Giant planets carry the lion's share of angular momentum in a stellar system. For example, Jupiter and Saturn contain 98 percent of the angular momentum in the solar system. Finally, a chemical tracer is the element lithium, which is normally destroyed inside stars. A newly devoured Jovian planet would provide a fresh supply of lithium to the star, and this shows up as an anomalous excess in the star's spectrum. In our solar system Jupiter is too far from the Sun to be swallowed up when the Sun expands to a red giant in about 5 billion years. However, detections of extrasolar planets do show that Jupiter-sized planets can orbit unexpectedly close to their parent stars. Some are even closer than Earth is to our Sun. These worlds are doomed to be eventually swallowed and incinerated.

24 GPS satellites orbit Earth.
Tick-Tock Atomic Clock

Modern navigators rely on atomic clocks. Instead of old-style springs or pendulums, the natural resonances of atoms -- usually cesium or rubidium -- provide the steady 'tick' of an atomic clock. The b ...
continue reading this fact
The Weightless Environment Brings Special Challenges To Astronauts. Mark Lee Tetherless and Free
Mixed Up In Space

Imagine waking up in space. Groggy from sleep, you wonder ... which way is up? And where are my arms and legs? Throw in a little motion sickness, and you'll get an idea of what it can feel like to be ...
continue reading this fact
False-color image of Jupiter
Jupiter's Great Red Spot - A Super Storm

The most prominent and well-known feature of the planet Jupiter is the Great Red Spot. It is not a surface feature, as the hard core of Jupiter lies at the bottom of an atmosphere that is thousands of ...
continue reading this fact

Science Quote

'We are all in the gutter, but some of us are looking at the stars.'

Oscar Wilde

All rights reserved. © Copyright '1995-'2018   Privacy Statement | Cookie Policy