Monday, January 30, 2023

Science in pills: LUMINOUS CIRCLES ABOVE HELICOPTERS

Spectacular rings of light that are generated on helicopters during operations in desert conditions. The enormous downward thrust of the rotors raises an unavoidable sand cloud which strikes the blades generating circles of light on the top of the helicopter.

Helicopter rotors (shown here a tiltrotor) are often made from titanium, stainless steel or nickel alloys. The effect is caused by the pyrophoric oxidation of metal particles. At the base is the so-called Kopp-Etchell effect. 


When a helicopter descends into a sandy environment, the enormous downward thrust from the rotors inevitably kicks up a cloud of sand. Once in the air, the helicopter’s blades cut through this cloud, generating the halo.

But how? To prevent early degradation, most helicopter blades are coated with an abrasion strip. This strip, typically crafted out of a metal like titanium or nickel, prevents the leading edge of the rotor blade from being worn down too quickly by the various particulate hazards of the atmosphere.



This abrasion strip can handle a lot of wear and tear, but the desert is a harsh environment. Sand is harder than the titanium and nickel that make up the abrasion strip, so when the blades begin cutting through a cloud of sand, the particles hit the blades and send bits of metal flying into the air.

It turns out that the metals that make up the abrasion strips on helicopter blades, bracing themselves against the stinging force of the sand, can be pyrophoric. This means that the metals used are substances that can spontaneously ignite in air. But of course this doesn’t happen in normal circumstances; we don’t see bricks of titanium bursting into flames. Rather, the spinning blades of the helicopter generate a cloud of metal particles, just like the cloud of sand. Once in a powdered form, the metal particles can ignite and create the brilliant scenes above.

Sunday, January 29, 2023

What are the Intergalactic stars?

An intergalactic star, also known as an intracluster star or a rogue star, is a star not gravitationally bound to any galaxy. Although a source of much discussion in the scientific community during the late 1990s, intergalactic stars are now generally thought to have originated in galaxies.

Stellar outcasts apparently aren’t that rare. The estimated number of intergalactic stars in the Virgo cluster alone may be over one trillion. Despite the vast amount of these stars, astronomers think the night-sky view from a planet orbiting an intergalactic star wouldn’t be very exciting. The star isn’t in a galaxy, so while there might be a few far-off galaxies that would be visible, inhabitants wouldn’t have the crowded, starry skies humans can see from Earth. The effect would be even worse if the planet does not have a moon.

What is the smallest thing ever photographed?

It is the shadow produced by… an atom.

A team of researchers from Griffith University in Queensland (Australia) wanted to understand how many atoms were needed to generate a shadow and realized, with considerable surprise, that only one was enough.

The researchers had to wait five years for the atom to freeze and for its shadow to become dark enough to be visible.

In detail, David Kielpinski and colleagues confined atomic ions of ytterbium, a soft silvery metal (whose atomic number is 70), in a trap kept under high vacuum and at a temperature of a few millikelvins.

Next, a single ion was struck by light of a specific frequency and cast its shadow on a detector.

Only then was the digital camera connected to a very high resolution electron microscope able to capture the image you see in the figure.

We've Never Found Anything Like The Solar System. Is It a Freak in Space?

Since the landmark discovery in 1992 of two planets orbiting a star outside of our Solar System, thousands of new worlds have been added to a rapidly growing list of 'exoplanets' in the Milky Way galaxy.

We've learnt many things from this vast catalogue of alien worlds orbiting alien stars. But one small detail stands out like a sore thumb. We've found nothing else out there like our own Solar System.

Hubble Telescope Spotted Young, Unstable Variable Star in Nebula

 V 372 Orionis, a very bright variable star, appears in a new image captured by the Hubble Space Telescope . Released this Friday (27) by the European Space Agency, the photo shows it next to a smaller neighboring star. Both are located within the Orion Nebula, a large star-forming region.

 The image was produced from data from the Advanced Camera for Surveys and Wide Field Camera 3 cameras, which captured light at infrared and visible wavelengths. As they merge, they reveal fascinating details of this region of the nebula.

Saturday, January 28, 2023

The Galactic Centre in Infrared

What does the centre of our galaxy look like? In visible light, the Milky Way's centre is hidden by clouds of obscuring dust and gas. But in this stunning vista, the Spitzer Space Telescope's infrared cameras, penetrate much of the dust revealing the stars of the crowded galactic centre region.

A mosaic of many smaller snapshots, this detailed, false-colour image shows older, cool stars in bluish hues. Red and brown glowing dust clouds are associated with young, hot stars in stellar nurseries. The very centre of the Milky Way has been found capable of forming newborn stars.

We Share Smarts with Octopuses, and Now We Know Why

Scientists say that the abundance of microRNA types in our brains is a sign of our intelligence, one which we share with octopuses and other cephalopods.

Octopuses are incredibly intelligent creatures, though their intelligence is dramatically different from our own. They benefit from a big, central brain in addition to an ancillary brain in each of their eight tentacles. The animals demonstrate strange problem-solving skills, moving through mazes and opening tough-to-split shells in ways we struggle to understand.

Dark matter particle that may finally shed light on cosmic mystery the 'best of both worlds'

A phase change in the early universe and particles called HYPERs could make dark matter detectable in future experiments.

A new dark matter model suggests a new candidate for the constituent particles of this mysterious form of matter that could mean it is detectable by future experiments.