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Archive for the 'UCL Science Picture of the Week' Category

The coolest place in London

By Oli Usher, on 18 May 2015

Quantum refrigerator. Photo: O. Usher (UCL MAPS)

Quantum refrigerator. Photo: O. Usher (UCL MAPS)

This photo shows a specialised refrigerator, used for cooling objects to within a fraction of absolute zero, located in the Physics building on UCL’s main campus.

When in operation, the refrigerator is entirely enclosed in a sealed and insulated housing, which has been removed here for maintenance.

As with a household fridge, the temperature drops as you go down – with the highest of the four shelves being at a temperature of about 50 Kelvins (-223 Celsius) and the bottom one at just 0.03 K (-273 C).

The refrigerator is used to cool small objects, such as transistors, down to levels where thermal effects (such as the vibration of the atoms in them) are eliminated, allowing quantum effects to be observed.

Samples can be raised or lowered through each shelf via a circular hole in the centre of the refrigerator.

The refrigerator is cooled by a mixture of liquid Helium-3 and Helium-4. The lowest shelf of this refrigerator has a strong claim to being the coldest place in London (alongside a handful of similar facilities at other London universities).

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X-Ray observations probe Sagittarius A*

By Oli Usher, on 14 May 2015

Sagittarius A*

Sagittarius A* region, as observed by NASA’s Chandra X-Ray Observatory. Credit: NASA/CXO

This image shows the centre of the Milky Way galaxy, as seen in X-rays by the Chandra X-Ray Observatory. X-rays are produced by high-temperature, high-energy phenomena.

Within this region lies Sagittarius A*, the Milky Way’s central black hole.

An international team of astronomers, including UCL’s Silvia Zane, has just published new research on a magnetar (a type of super-magnetic neutron star) that is orbiting Sagittarius A*, explaining why it is cooling far slower than theories suggest.

New space photos from UCL’s observatory

By Oli Usher, on 29 April 2015

Messier 51, from the University of London Observatory. Credit: UCL/ULO/Ian Howarth

Messier 51, from the University of London Observatory. Credit: UCL/ULO/Ian Howarth

The University of London Observatory – UCL’s astronomical observatory in Mill Hill, North London – has to deal with England’s murky skies and London’s bright lights, but it can still make some impressive images. Messier 51, seen in the picture above, is actually not one galaxy but two – a large spiral galaxy (Messier 51a) interacting with a smaller dwarf galaxy (NGC 5195). Over the next few hundred million years, they will merge together into one larger galaxy.

Such mergers are quite common. Large spiral galaxies can absorb dwarf galaxies without major disruption to their shapes, though the (rarer) mergers between similarly-sized galaxies tend to destroy all structure, leaving a largely featureless elliptical galaxy. This will be the fate of the Milky Way when it merges with the Andromeda Galaxy in a few billion years time.

The Messier 51 pair are a popular target for amateur astronomers – on a dark night, even relatively basic telescopes can pick out the very faint comma-shape of the galaxy pair, visible near one end of the Plough (Ursa Major).

The picture is one of several newly processed images just published by UCL’s observatory, based on data gathered by astronomy students. The observatory now routinely archives all the digital data gathered with its Celestron telescopes, which are used intensively for undergraduate teaching. This growing archive of data means that multiple observations can be easily combined into a single image, improving contrast and revealing faint details that would otherwise be invisible.

A selection of several dozen of these images from the observatory, with multiple observations processed and combined to form colour composites, is available online to the public. They are free to reuse and reproduce.

Darkness falls across the land

By Dewi W Lewis, on 24 March 2015

 

eclipse

These two photographs were taken in the quad during the eclipse. The first at 9:25 the second at 9:31am.

During this time the light dropped by a factor of 16: dropping from an Exposure Value (EV) value of 11 to 7, or 4 stops, to the photographers amongst you.

My eyes told me it got “a bit darker”, the reality was far more!

Hydrophobic art

By Oli Usher, on 5 March 2015

paint

Yau Lu (UCL Chemistry) is the lead author of some research which hit the headlines last week. His team has succeeded in making a water-resistant and self-cleaning coating which is both highly effective and very strong. Previous coatings have been weak, and easily scratched or flaked off.

Here, he shows how the hydrophobic  paint can be used to create a water-repellent design on glass. The hydrophobic coating, water and dye all come together to create an ephemeral artwork:

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Where noble gases won UCL a Nobel Prize

By Oli Usher, on 2 March 2015

IMG_0073-cc

Readers familiar with UCL will immediately recognise the Slade School of Fine Art – the North Wing on UCL’s historic (and grade I listed) quadrangle. What they may not know is that the building, which dates back to the 1870s, was originally also home to UCL’s Department of Chemistry.

It was in this building that some of UCL’s most famous contributions to chemistry were made: William Ramsay and his successor J Norman Collie both worked here.

In fact, as far as we can work out, it is the building in the world which has seen the discovery of the greatest number of chemical elements. Ramsay discovered argon, neon, krypton and xenon while working here, as well as isolating helium (which had been seen in the spectrum of the Sun, but not observed here on Earth) and radon. These elements are together known as the noble gases, and Ramsay’s discoveries secured for him the 1904 Nobel Prize in Chemistry – UCL’s first.

In 1913, the year of Ramsay’s retirement, UCL’s Chemistry department moved to a new purpose-built lab immediately behind its old home. The building – which still houses some of the department’s laboratories and offices – is now named after another towering figure in chemistry: Kathleen Lonsdale.

After a century of heavy use and piecemeal remodelling, the building is looking a little tired . A multi-million pound complete refurbishment of the building is planned to begin later this year.

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Twinkle: a new mission to study distant planets

By Oli Usher, on 9 February 2015

Twinkle. Credit: SSTL/Twinkle/DSS

A new satellite for observing extrasolar planets could be in orbit within four years, under plans drawn up by UCL and Surrey Satellite Technology Limited (SSTL). The Twinkle satellite, pictured above, will observe the light of distant stars with planets orbiting them.

As a planet passes between the star and Twinkle’s telescope, a small amount of the light passes through its atmosphere, imprinting on it the chemical signature of its atmosphere. This technique has been used by Hubble to analyse the atmospheres of a handful of exoplanets, but the Twinkle team hopes to probe at least 100 during the spacecraft’s mission.

UCL leads a consortium of UK institutes who will construct Twinkle’s scientific instrumentation, a highly precise infrared spectrometer which can tease out the faint signature of the planetary atmospheres from the starlight.

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Asteroid’s close encounter with Earth – the UCL view

By Oli Usher, on 2 February 2015

2004 BL86

Last week, asteroid 2004 BL86 passed near Earth. The ball of rock, a little over 300 metres across, passed 3.1 lunar distances from Earth.

This is far enough not to be of any serious concern – but it is closer than any other known asteroid will come to us until 2027. If an asteroid like 2004 BL86 were to hit Earth, we could expect widespread destruction – the famous Barringer Crater in Arizona was gouged out by an object just 50 metres across.

During its close approach, UCL’s observatory spotted the asteroid and snapped the picture above: a series of 30 second exposures separated by 9 second gaps. The asteroid can be seen moving rapidly against the background stars as the telescope was programmed to track the movement of the stars.

Reprogramming the telescope to hold the asteroid in its sights creates the image below – with the stars appearing as streaks instead.

2004 BL86

This video, featuring a series of observations of the asteroid made at the observatory over the night of 26-27 January, shows both types of observation, including a long shot tracking the asteroid across the sky.

Images by Steve Fossey, Theo Schlichter and Ian Howarth.

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A molecule-sized magnetic sensor

By Oli Usher, on 26 January 2015

STM image of iron phtalocyanine. Credit: Ben Warner, Fadi El Hallak and Cyrus Hirjibehedin (LCN)

STM image of iron phtalocyanine. Credit: Ben Warner, Fadi El Hallak and Cyrus Hirjibehedin (LCN)

This image shows a scanning tunnelling microscope (STM) image of a molecule of iron phtalocyanine, separated from an underlying layer of copper by a thin barrier of copper nitride.

The image is part of a new piece of research just published by UCL scientists. The iron phtalocyanine molecule forms part of a tiny magnetic sensor which is sufficiently sensitive that it can detect molecule-sized magnetic fields. This technology could allow far smaller hard disks and new computer memory designs.

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PanCam taking shape

By Oli Usher, on 8 December 2014

UCL’s contribution to the ExoMars Rover – the European Mars mission scheduled for touchdown in 2019 – is gradually taking shape. Quite literally.

The ExoMars PanCam optical bench being milled. Photo: MSSL

The ExoMars PanCam optical bench being milled. Photo: MSSL

This photo shows a prototype of the main structure of the panoramic camera (PanCam) instrument being machined out of a block of metal. PanCam will be the rover’s primary camera, producing high resolution 3D images of the Martian surface, and it is being being built by scientists and engineers at UCL’s Mullard Space Science Laboratory.

The ExoMars PanCam optical bench. Photo: MSSL

The Finished product. Photo: MSSL

The structure is known as the ‘optical bench’. All the precision-built optical components, including detectors, lenses, mirrors and filter wheels (below), will be attached to this rigid housing.

Filter wheels for ExoMars PanCam. Photo: MSSL

Filter wheels for ExoMars PanCam. Photo: MSSL

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