The Ghost Head Nebula

NGC 2080. Credit: Mohammad Heydari-Malayeri (Observatoire de Paris) et al

This image from NASA's Hubble Space Telescope reveals a vibrant green and red nebula far from Earth, where nature seems to have put on the traditional colours of the season. These colours, produced by the light emitted by oxygen and hydrogen, help astronomers investigate the star-forming processes in nebulas such as NGC 2080.

The light from the nebula captured in this image is emitted by two elements, hydrogen and oxygen. The red and the blue light are from regions of hydrogen gas heated by nearby stars. The green light on the left comes from glowing oxygen. The energy to illuminate the green light is supplied by a powerful stellar wind (a stream of high-speed particles) coming from a massive star just outside the image.

The white region in the center is a combination of all three emissions and indicates a core of hot, massive stars in this star-formation region. The intense emission from these stars has carved a bowl-shaped cavity in the surrounding gas.

In the white region, the two bright areas (the "eyes of the ghost") - named A1 (left) and A2 (right) - are very hot, glowing "blobs" of hydrogen and oxygen. The bubble in A1 is produced by the hot, intense radiation and powerful stellar wind from a single massive star. A2 has a more complex appearance due to the presence of more dust, and it contains several hidden, massive stars. The massive stars in A1 and A2 must have formed within the last 10,000 years, since their natal gas shrouds are not yet disrupted by the powerful radiation of the newly born stars.

This "enhanced colour" picture spanning 55 light years in the above image is composed of three narrow-band-filter images obtained with Hubble's Wide Field Planetary Camera 2. The colours are red (ionized hydrogen, H-alpha, 1040 seconds), green (ionized oxygen, 1200 seconds) and blue (ionized hydrogen, H-beta, 1040 seconds).

The Ghost Head Nebula NGC 2080 is a star forming region in the Large Magellanic Cloud, a satellite galaxy of our own Milky Way.

Halloween's ancient & astronomical origins date back to the ancient Celtic festival of Samhain (pronounced sow-in).
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The Celts, who lived 2,000 years ago in the area that is now Ireland, the United Kingdom, and northern France, celebrated their new year on November 1. This day marked the end of summer and the harvest and the beginning of the dark, cold winter, a time of year that was often associated with human death. Celts believed that on the night before the new year, the boundary between the worlds of the living and the dead became blurred. On the night of October 31, they celebrated Samhain, when it was believed that the ghosts of the dead returned to earth. In addition to causing trouble and damaging crops, Celts thought that the presence of the otherworldly spirits made it easier for the Druids, or Celtic priests, to make predictions about the future. For a people entirely dependent on the volatile natural world, these prophecies were an important source of comfort and direction during the long, dark winter.

To commemorate the event, Druids built huge sacred bonfires, where the people gathered to burn crops and animals as sacrifices to the Celtic deities.

During the celebration, the Celts wore costumes, typically consisting of animal heads and skins, and attempted to tell each other's fortunes. When the celebration was over, they re-lit their hearth fires, which they had extinguished earlier that evening, from the sacred bonfire to help protect them during the coming winter.

By A.D. 43, Romans had conquered the majority of Celtic territory. In the course of the four hundred years that they ruled the Celtic lands, two festivals of Roman origin were combined with the traditional Celtic celebration of Samhain.

The first was Feralia, a day in late October when the Romans traditionally commemorated the passing of the dead. The second was a day to honor Pomona, the Roman goddess of fruit and trees. The symbol of Pomona is the apple and the incorporation of this celebration into Samhain probably explains the tradition of "bobbing" for apples that is practiced today on Halloween.

By the 800s, the influence of Christianity had spread into Celtic lands. In the seventh century, Pope Boniface IV designated November 1 All Saints' Day, a time to honor saints and martyrs. It is widely believed today that the pope was attempting to replace the Celtic festival of the dead with a related, but church-sanctioned holiday. The celebration was also called All-hallows or All-hallowmas (from Middle English Alholowmesse meaning All Saints' Day) and the night before it, the night of Samhain, began to be called All-hallows Eve and, eventually, Halloween. Even later, in A.D. 1000, the church would make November 2 All Souls' Day, a day to honor the dead. It was celebrated similarly to Samhain, with big bonfires, parades, and dressing up in costumes as saints, angels, and devils. Together, the three celebrations, the eve of All Saints', All Saints', and All Souls', were called Hallowmas.

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Seeing Colour in Nebulae from A Quantum Diaries Survivor
Celestial Mandrill Is A Cosmic Ghost from Scientific Blogging
Astronomers simulate life & death in the Universe from Science Daily
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Stellar Jewel Box

Star Cluster Bursts into Life in New Hubble Image. Click Image to Enlarge

Thousands of sparkling young stars are nestled within the giant nebula NGC 3603. This stellar "jewel box" is one of the most massive young star clusters in the Milky Way Galaxy.

NGC 3603 is a prominent star-forming region in the Carina spiral arm of the Milky Way, about 20,000 light-years away. This latest image from NASA's Hubble Space Telescope shows a young star cluster surrounded by a vast region of dust and gas. The image reveals stages in the life cycle of stars.

The nebula was first discovered by Sir John Herschel in 1834.
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Extreme star cluster in new Hubble images ESA Zoom-in animation.
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Beta Pictoris

NASA's Hubble Space Telescope revealed two dust disks circling the nearby star Beta Pictoris. The images confirm a decade of scientific speculation that a warp in the young star's dust disk may actually be a second inclined disk, which is evidence for the possibility of a planet that is at least as big as Neptune. Credit: NASA

Puffy debris disks around three nearby stars could harbour Pluto-sized planets-to-be, a new computer model suggests.

The "planet embryos" are predicted to orbit three young, nearby stars, located within about 60 light years or less of our solar system. Beta Pictoris & AU Microscopii are both about 12 million years old, while a third star, Fomalhaut, is aged at 200 million years old.


If confirmed, the objects would represent the first evidence of a never-before-observed stage of early planet formation. Another team recently spotted "space lint" around a nearby star that pointed to an even earlier phase of planet building, when baseball-sized clumps of interstellar dust grains are colliding together.

The thickness of a dust ring or debris disk depends on the size of objects orbiting inside it. The ring of dust thins as the star system ages, but if enough dust has clumped together to form an embryonic planet, it knocks the other dust grains into eccentric orbits. Over time, this can puff up what was a razor-thin disk.

The new finding will be detailed in an upcoming issue of the Monthly Notices of the Royal Astronomical Society.
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Solar Storm rips tail of Comet - from NASA. See short movie
Circumstellar Debris Disks resemble our Kuiper Belt from Hubble
Dawn's early light, Ceres & Vesta by Amara @ Scientific Blogging
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Planetary Nebulae

Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) STScI-PRC07-33a

The colourful, intricate shapes in these NASA Hubble Space Telescope images reveal how the glowing gas ejected by dying Sun-like stars evolves dramatically over time.

These gaseous clouds, called planetary nebulae, are created when stars in the last stages of life cast off their outer layers of material into space. Ultraviolet light from the remnant star makes the material glow. Planetary nebulae last for only 10,000 years, a fleeting episode in the 10-billion-year lifespan of Sun-like stars.

The name planetary nebula has nothing to do with planets. They got their name because their round shapes resembled planets when seen through the small telescopes of the eighteenth century.

The Hubble images show the evolution of planetary nebulae, revealing how they expand in size and change temperature over time. A young planetary nebula, such as He 2-47, is small and dominated by relatively cool, glowing nitrogen gas. In the Hubble images, the red, green, and blue colours represent light emitted by nitrogen, hydrogen, and oxygen, respectively.

Over thousands of years, the clouds of gas expand away and the nebulae become larger. Energetic ultraviolet light from the star penetrates more deeply into the gas, causing the hydrogen and oxygen to glow more prominently, as seen near the center of NGC 5315. In the older nebulae, such as IC 4593, at bottom, left, and NGC 5307, at bottom, right, hydrogen and oxygen appear more extended in these regions, and red knots of nitrogen are still visible.
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These four nebulae all lie in our Milky Way Galaxy. Their distances from Earth are all roughly the same, about 7,000 light-years. The snapshots were taken with Hubble's Wide Field Planetary Camera 2 in February 2007. Like snowflakes, planetary nebulae show a wide variety of shapes, indicative of the complex processes that occur at the end of stellar life.

He 2-47, is dubbed the "starfish" because of its shape. The six lobes of gas and dust, which resemble the legs of a starfish, suggest that He 2-47 puffed off material at least three times in three different directions. Each time, the star fired off a narrow pair of opposite jets of gas. He 2-47 is in the southern constellation Carina.

NGC 5315, the chaotic-looking nebula at top, reveals an x-shaped structure. This shape suggests that the star ejected material in two different outbursts in two distinct directions. Each outburst unleashed a pair of diametrically opposed outflows. NGC 5315 lies in the southern constellation Circinus.

IC 4593, is in the northern constellation Hercules. NGC 5307, displays a spiral pattern, which may have been caused by the dying star wobbling as it expelled jets of gas in different directions. NGC 5307 resides in the southern constellation Centaurus.

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A Grand Vision for European Astronomy from ESO
A New Reduction of the Hipparcos Catalogues from ESA
Mysterious radio signal from deep space @ Cosmos Magazine
Mysterious Energy Burst Stuns Astronomers from Science Daily
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Uncovering the Veil Nebula

The Veil Nebula from Vimeo. Click on arrows for full screen view.

When a star significantly heavier than our Sun runs out of fuel, it collapses and blows itself apart in a catastrophic supernova explosion. A supernova releases so much light that it can outshine a whole galaxy of stars put together.

The exploding star sweeps out a huge bubble in its surroundings, fringed with actual stellar debris along with material swept up by the blast wave. This glowing, brightly-coloured shell of gas forms a nebula: a supernova remnant. Such a remnant can remain visible long after the initial explosion fades away.

Scientists estimate that the supernova explosion occurred some 5000 to 10 000 years ago and could have been witnessed and recorded by ancient civilizations. These would have seen a star increase in brightness to roughly the brightness of the crescent Moon.
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A series of three new images taken with the NASA/ESA Hubble Space Telescope reveals magnificent sections of one of the most spectacular supernova remnants in the sky - the Veil Nebula. The entire shell spans about 3 degrees, corresponding to about 6 full Moons. The small regions captured in the new Hubble images provide stunning close-ups of the Veil. Fascinating smoke-like wisps of gas are all that remain visible of what was once a Milky Way star.



The intertwined rope-like filaments of gas in the Veil Nebula result from the enormous amounts of energy released as the fast-moving debris from the explosion ploughs into its surroundings and creates shock fronts. These shocks, driven by debris moving at 600 000 kilometres per hour, heat the gas to millions of degrees. It is the subsequent cooling of this material that produces the brilliantly coloured glows.

Like the larger scale ground-based observations, the high-resolution Hubble images display two characteristic features: sharp filaments and diffuse emission. These correspond to two different viewing geometries: sharp filaments correspond to an edge-on view of a shock front, and diffuse emission corresponds to a face-on view.



The Hubble images of the Veil Nebula are striking examples of how processes that take place hundreds of lightyears away can sometimes resemble effects we see around us in our daily life. The structures have similarities to the patterns formed by the interplay of light and shadow on the bottom of a swimming pool, rising smoke or ragged cirrus clouds.



Supernovae are extremely important for understanding our own Milky Way. Although only a few stars per century in our Galaxy will end their lives in this spectacular way, these explosions are responsible for making all chemical elements heavier than iron in the Universe. Many elements, such as copper, mercury, gold, iodine and lead that we see around us here on Earth today were forged in these violent events thousands of millions of years ago.
The expanding shells of supernova remnants were mixed with other material in the Milky Way and became the raw material for new generations of stars and planets.

The chemical elements that constitute the Earth, the planets and animals we see around us - and as a matter of fact our very selves - were built deep inside ancient stars and in the supernova explosions that result in the nebula we are seeing here. The green in the grass and the red of our blood are indeed the colours of stardust.

Also known as Cygnus Loop, the Veil Nebula is in the constellation of Cygnus, the Swan, about 1500 lightyears away from Earth.

Wide-field ground-based photo of the Veil Nebula
Image credit & copyright: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration. Acknowledgment: J. Hester (Arizona State University)

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Sun shakes Earth's Magnetic Field

Killer electrons from Vimeo. Click on arrows for full screen view

ESA's Cluster Mission helps reveal how the Sun shakes the Earth's magnetic field.

Space is a hostile region for astronauts & satellites. One constituent of this hazardous environment around the Earth are very energetic electrons, able to perturb or permanently damage satellites.

Ultra Low Frequency (ULF) waves, which travel along the Earth's magnetic field lines, are a prime candidate for generating these killer electrons, but the source of these waves remains unclear.
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A recent study using ground based instrumentation and a dozen satellites at a range of altitudes, provides a means to trace the energy source of these waves from the solar wind into the Earth's magnetosphere down to the ground.

Part of this satellite constellation, the four spacecraft of the ESA Cluster mission, was located at the border of the magnetosphere and played a major role in discriminating between the various theoretical ULF wave generation scenarios.

Quasi-sinusoidal oscillations of the magnetic field lines with periods of a few minutes were recorded continuously for several hours,
as if a celestial musician had plucked the magnetic field lines or strings of the Earth's magnetic guitar

Several ways of exciting these waves have been proposed. Most of them involve the solar wind as the external driver. The solar wind is a continuous stream of solar particles impacting and shaping the Earth's magnetic environment. However, understanding the global nature of these geomagnetic pulsations and the tracing of the energy transfer from the solar wind to the ground is a difficult task.

It requires a fortuitous alignment of several satellites, together with ground–based instruments to observe the oscillations simultaneously.

More from ESA releases
A space armada and ground based instruments to track ULF waves
Image & Simulation Credit: Andy Kale, University of Alberta
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'Killer' electrons in orbit explained by Heather Catchpole @ Cosmos Magazine
Killer Electrons In Space Are Now Less Mysterious from Science Daily releases

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ESA's Earth Explorer Mission

Getting the low down on gravity

The Gravity field and steady-state Ocean Circulation Explorer GOCE mission, due to be launched in spring 2008, is ESA's first satellite dedicated to measuring the Earth’s gravity – a fundamental force of nature that influences many dynamic processes within the Earth’s interior, and on and above its surface.

By measuring the Earth's gravity field and modelling the geoid, or hypothetical surface of the Earth, with extremely high accuracy and spatial resolution, GOCE will significantly advance our knowledge of how the Earth works in several domains – oceanography, geophysics and geodesy – as well as providing insight into the physics and dynamics of the Earth's interior, such as volcanism and earthquakes.

Because the gravitational signal is stronger closer to the Earth, GOCE has been designed to fly in a particularly low orbit - at an altitude of just 250 km. However, the remaining atmosphere at low altitudes creates a demanding environment for the satellite and presented a challenge for its design.

Unlike other missions where various independent instruments are carried aboard the spacecraft, GOCE is unique in that the instrumentation actually forms part of the structure of the satellite. A completely stable, rigid and unchanging local environment is required to acquire extremely high fidelity ‘true’ gravity readings, so the spacecraft intentionally has no mechanical moving parts.

Animation & more @ ESA’s Earth Explorer gravity satellite on show
Image Credits: ESA – AOES Medialab
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Phenomenological Quantum Gravity by Bee @ Backreaction
Phenomenology of Quantum Gravity by Lubos @ The Reference Frame
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A Window to the Stars

ESA’s orbiting gamma-ray observatory, Integral, has made a pioneering unequivocal discovery of radioactive iron-60 in our galaxy that provides powerful insight into the workings of massive stars that pervade and shape it.

Found drifting in space, the radioactive isotope has been sought for long. All past reported sightings of iron-60 have been subject to controversy. Now Integral has provided unequivocal evidence.
Since late 2002, Integral has been collecting data from across the galaxy. It shows an enhancement in gamma rays at two characteristic energies, 1173 and 1333 kilo electron Volts. These are produced by radioactive decay of iron-60 into cobalt-60.
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Roland Diehl of the Max-Planck-Institut für extraterrestrische Physik, headed the work and believes it is a major step forward. “These gamma-ray lines have been detected before with some dispute. Integral, the only instrument capable of doing this, shows that iron-60 does exist in interstellar space in our Galaxy,” he says.

More than a curiosity, its presence opens a door into the very heart of the most massive stars in the cosmos. The majority of chemical elements are built inside stars from raw ingredients present during star formation from an interstellar gas cloud. In addition to hydrogen and helium produced during the Big Bang, the gas contained enrichments, known to astronomers as ‘metals’, from previous generations of stars and their nuclear reactions.

Until this detection, astronomers had only one radioactive isotope to probe into the current build-up of chemical elements in stars and their distribution with respect to future star formation. That was the radioactive isotope aluminium-26, first discovered in 1978. “The study of aluminium-26 has developed into its own branch of astronomy,” says Diehl.

Iron-60 gives astronomers valuable new insight - although produced in the same stars as aluminium-26, its production differs markedly. Iron-60 is synthesised both later in a star’s life and deeper inside.

As massive stars age, they develop a layered structure in which different chemical elements are fused together. While aluminium-26 is one rung on the ladder of nuclear reactions, iron-60 is produced from pre-existing stable iron isotopes by a process called ‘neutron capture’ in the respective layers where helium and carbon atoms are undergoing fusion.

“Iron-60 provides the entry into studying neutron capture in stars through contemporaneous radioactivity,” says Diehl. It has also prompted a number of particle accelerators to begin more detailed studies of how easily iron captures neutrons.

Unlike aluminium-26, iron-60 is only expelled into space when the star explodes at the end of its life. It then decays with a half-life of 1.5 million years, producing the gamma rays that Integral detected.

The new data pins down the ratio of iron-60 to aluminium-26, which has a half-life of 740 000 years. Previous predictions have fallen anywhere between 10 and 100 percent. Integral shows it to be 15 percent, which agrees well with current theoretical estimates. But theoreticians and nuclear physicists have been stimulated by Integral’s results to strive for more precise predictions.

Radioactive iron, a window to the stars from ESA and Max Planck Institut

Although Integral clearly sees the telltale gamma rays, they are too faint for it to map out enhancements and paucities across the Galaxy. Mapping the distribution of iron-60 is a job for the next generation of gamma-ray instruments.

Nevertheless, the team will continue observing with Integral for as long as they can, in the hope of gaining some coarse ideas about the isotope’s spread across the Galaxy.
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GZK cut-off Cosmic Rays & Cosmic Showers from Bee @ Backreaction
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XMM Newton. The Next Decade

Science Worshops

Thanks to the recent generation of high energy observatories, astrophysics is witnessing a golden age of discovery in the X-ray domain.

Current technical evaluation demonstrates that the XMM-Newton spacecraft and its scientific instruments can continue to provide first class X-ray observations far into the next decade.

Other missions to be launched soon, like Herschel, Planck, GLAST, as well as new ground-based developments, will open up new challenging opportunities for multi-wavelength and follow-up observations to which XMM-Newton is ideally placed to make a major contribution.
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Star Formation

A new Star is Born


Star formation results in a complicated system in which the young star is surrounded by a disc of gas and dust. This matter then follows one of three different routes. It finds its way onto the star through magnetic funnels, or stays in the disc to form planets, or is thrown clear of the system in a wind or jet created by the overall magnetic field.

XMM-Newton was used to target stars in the nearby Taurus Molecular Cloud. This vast cloud in space is one of the star-forming regions nearest to Earth and contains over 400 young stars.

The results defy astronomers’ expectations, as the streams of falling matter interact with the hot corona, cooling it, while the ejected streams of gas heat up in shocks as they are ejected from the star.

Most of these stars are still accumulating matter, a process known as accretion. As falling matter strikes the surface of the star, it typically doubles the temperature of the surface from 5000 Kelvin to 10 000 Kelvin. This produces an excessive amount of ultraviolet radiation emitted by the star and detected by XMM-Newton’s Optical Monitor. Astronomers had thought that the same shock waves that caused the emission of the ultraviolet excess should also produce an excess of X-rays.

Taurus Molecular Cloud Credits:(FCRAO), Gopal Narayanan / Mark Heyer
X-ray young stars in Taurus region Credits: ESA/XMM-Newton/Paul Scherrer Institut
XMM-Newton reveals X-rays from gas streams around young stars from ESA
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XMM-Newton deciphers the magnetic physics around forming stars
Special feature from Astronomy & Astrophysics
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A Close Neighbour

Andromeda, the nearest major galaxy to the Milky Way, is shown here in this wide-field optical image from Kitt Peak.

Located in the constellation of Andromeda (the Princess), the Andromeda Galaxy is a large spiral galaxy over 65,000 light years in diameter and approximately 2.9 million light years from Earth.
(Credit: NOAO/AURA/NSF/T.Rector & B.A.Wolpa)

The central region of Andromeda is shown in a composite image, with X-rays from NASA's Chandra X-ray Observatory (blue) combined with the optical image. Astronomers believe that Andromeda, also known as Andromeda Galaxy (M31), and the Milky Way will merge in a few billion years.

In the composite image (insert), hot, X-ray bright gas is seen to envelop the middle of Andromeda. Point sources are also prominent, which mostly reveal pairs of stars that are interacting with each other. Many of these double stars are thought to include white dwarfs pulling large amounts of material away from a companion star. When the amount of gas being dumped onto the white dwarf gets too high a thermonuclear explosion occurs on the surface of the white dwarf, emitting bright X-rays. (Credit: NASA/CXC/MPE/W.Pietsch et al)

Andromeda Galaxy (M31):
A New Look at a Close Neighbor from Chandra
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Cat's Eye Nebula

The Cat's Eye Nebula from Hubble Credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA) Click on Image to Enlarge

Staring across interstellar space, the alluring Cat's Eye nebula lies three thousand light-years from Earth. A classic planetary nebula, the Cat's Eye (NGC 6543) represents a final, brief yet glorious phase in the life of a sun-like star. This nebula's dying central star may have produced the simple, outer pattern of dusty concentric shells by shrugging off outer layers in a series of regular convulsions.
But the formation of the beautiful, more complex inner structures is not well understood. Seen so clearly in this sharp Hubble Space Telescope image, the truly cosmic eye is over half a light-year across. Of course, gazing into the Cat's Eye, astronomers may well be seeing the fate of our sun, destined to enter its own planetary nebula phase of evolution ... in about 5 billion years.
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Bow Shocks

Credits: NASA/ESA and The Hubble Heritage Team STScI/AURA


The shock wave that sits above the Earth’s surface is a natural phenomenon. It is located on the side facing the Sun, at approximately one quarter of the distance to the Moon, and is caused by the flow of electrically charged particles from the Sun.

This flow of electrically charged particles known as solar wind is emitted in a gusty manner by the Sun. When it collides with the Earth’s magnetic field, it is abruptly slowed down and this causes a barrier of electrified gas, called the bow shock, to build up. It behaves in the same way as water being pushed out of the way by the front of a ship.

On 24 January 2001, the four Cluster spacecraft were flying at an approximate altitude of 105 000 kilometres, in tetrahedron formation. Each spacecraft was separated from the others by a distance of about 600 kilometres. With such a distance between them, as they approached the bow shock, scientists expected that every spacecraft would record a similar signature of the passage through this region.

Instead, the readings they got were highly contradictory. They showed large fluctuations in the magnetic and electric field surrounding each spacecraft. They also revealed marked variations in the number of solar wind protons that were reflected by the shock and streaming back to Sun.

The detection has implications for the way astronomers investigate larger bow shocks around distant celestial objects. Bow shocks are related to some of the most energetic events in the Universe. Exploding stars and strong stellar winds from young stars cause them. Reforming bow shocks can also accelerate particles to extremely high energies and throw them across space.

Although the conditions that cause the reformation of a shock wave are rare around the Earth, they are common around these other celestial objects.

Cluster makes a shocking discovery ESA Press Release
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New Horizons & Other Starships - Where are they now? from Astroprof
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COROT detects Oscillations

COROT discovers its first Exoplanet and detects oscillations in a Sun-like star

COROT has detected its first seismic oscillations in the light curve of a sun-like star. The research team for spacecraft COROT revealed the first discoveries of this major European mission on 3rd of May.

The satellite has also found a very hot exoplanet and provisional estimates indicate it has a very large radius.

Based on the quality of this initial data, our knowledge of planets outside our own solar system, known as exoplanets, and of the interiors of stars should be vastly improved over the next three years.

The exoplanet, which has been named COROT-exo-1b, orbits around a yellow dwarf star similar to our Sun in about 1.5 days. It is situated roughly 1500 light years from us, in the direction of the constellation of the Unicorn (Monoceros). The oscillating star is of a similar type and located in the same region of the sky, but much nearer to us.

The satellite has two main advantages over ground-based projects. Firstly, it can observe the same stars continuously, without interruption, for up 150 days (60 days so far). Secondly, its position above the Earth’s atmosphere enables it to measure the brightness variations of stars much more precisely.

COROT detects planets by looking for transits, small dips in the apparent brightness of a star caused by a planet passing in front of it. While its first planet is large, the quality of the data suggests COROT will be able to identify rocky planets only a few times larger than our own Earth.

COROT may also be able to observe variations in the amount of stellar light reflected towards us by planets as they go around their orbits, giving some indication of their atmospheric properties.
SciTech Press Release 3rd May 2007.
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SOHO & Sun Ripples

The Solar and Heliospheric Observatory (SOHO) may have glimpsed long-sought oscillations on the Sun’s surface.

The subtle variations reveal themselves as a miniscule ripple in the overall movement of the solar surface. Astronomers have been searching for ripples of this kind since the 1970s, when they first detected that the solar surface was oscillating in and out.

The so-called ‘g-modes’ are driven by gravity and provide information about the deep interior of the Sun. They are thought to occur when gas churning below the solar surface plunges even deeper into our star and collides with denser material, sending ripples propagating through the Sun’s interior and up to the surface. It is the equivalent of dropping a stone in a pond.

Unfortunately for observers, these waves are badly degraded during their passage to the solar surface. By the time g-modes reach the exterior, they are little more than ripples a few metres high.

Until now, the rotation rate of the solar core was uncertain. If the the Global Oscillation at Low Frequency (GOLF) - instrument on SOHO -detection is confirmed, it will show that the solar core is definitely rotating faster than the surface.

The rotation speed of the solar core is an important constraint for investigating how the entire Solar System formed, because it represents the hub of rotation for the interstellar cloud that eventually formed the Sun and all the bodies around it.

The next step for the team is to refine the data to increase their confidence in the detection, by incorporating data from other instruments, both on SOHO and at ground-based observatories.

SOHO's quest for solar ripples from ESA
A Massive Explosion on the Sun from NASA
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Galileo Constellation

Artist's impression of Galileo satellite constellation. Credits: ESA-J. Huart

Call for ideas in satellite navigation - Galileo Masters 2007

When fully deployed in 2011-2012, Galileo, Europe’s own global navigation satellite system, will be the world’s first completely civilian positioning system. Galileo will provide a highly accurate, guaranteed global positioning service and will be inter-operable with GPS and GLONASS, the two other global satellite navigation systems. Galileo is a joint initiative between ESA and the European Commission.

The fully deployed Galileo system will consist of 30 satellites, 27 operational plus 3 active spares, positioned in three circular Medium Earth Orbit (MEO) planes at 23 222 km altitude above the Earth.
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A step closer to a European Space Policy
Track ESA spacecraft online in Real Time
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Catastrophes in the Solar System

Earth sits between two worlds that have been devastated by climate catastrophes. In the effort to combat global warming, our neighbours can provide valuable insights into the way climate catastrophes affect planets.

Modelling Earth’s climate to predict its future has assumed tremendous importance in the light of mankind’s influence on the atmosphere. The climate of our two neighbours is in stark contrast to that of our home planet, making data from ESA’s Venus Express and Mars Express invaluable to climate scientists.
Venus is a cloudy inferno whilst Mars is a frigid desert. As current concerns about global warming have now achieved widespread acceptance, pressure has increased on scientists to propose solutions.

The atmosphere of Venus is much thicker than Earth’s. Nevertheless, current climate models can reproduce its present temperature structure well. Now planetary scientists want to turn the clock back to understand why and how Venus changed from its former Earth-like conditions into the inferno of today.

They believe that the planet experienced a runaway greenhouse effect as the Sun gradually heated up. Astronomers believe that the young Sun was dimmer than the present-day Sun by 30 percent. Over the last 4 thousand million years, it has gradually brightened. During this increase, Venus’s surface water evaporated and entered the atmosphere.

“Water vapour is a powerful greenhouse gas and it caused the planet to heat-up even more. This is turn caused more water to evaporate and led to a powerful positive feedback response known as the runaway greenhouse effect.”

As Earth warms in response to manmade pollution, it risks the same fate. Reconstructing the climate of the past on Venus can give scientists a better understanding of how close our planet is to such a catastrophe. However, determining when Venus passed the point of no return is not easy. That’s where ESA’s Venus Express comes in.

The spacecraft is in orbit around Venus collecting data that will help unlock the planet’s past. Venus is losing gas from its atmosphere, so Venus Express is measuring the rate of this loss and the composition of the gas being lost. It also watches the movement of clouds in the planet’s atmosphere. This reveals the way Venus responds to the absorption of sunlight, because the energy from the Sun provides the power that allows the atmosphere to move.

In addition, Venus Express is charting the amount and location of sulphur dioxide in the planet’s atmosphere. Sulphur dioxide is a greenhouse gas and is released by volcanoes on Venus.

What happened on these two worlds is very different but either would be equally disastrous for Earth. We are banking on our ability to accurately predict Earth’s future climate.

Climate catastrophes in the Solar System ESA press release 26 April 2007
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Gliese and Earth-like Worlds from Centauri Dreams
NASA's AIM Mission Soars To The Edge Of Space
Satellites Play Vital Role In Understanding The Carbon Cycle
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The Future starts Today

Hubble mosaic of the galaxy NGC 7319 from Stephan's Quintet.
Located in the constellation Pegasus, 270 million light-years from Earth, it was discovered by Edouard M. Stephan in 1877. As the name suggests, the quintet actually contains five galaxies and is the first compact group ever discovered.

One step closer to shaping ‘Cosmic Vision 2015-2025’

“The future starts today” said ESA’s Director General Jean-Jacques Dordain, addressing the community on 11 April 2007.
Following the call for proposals issued early March this year, ESA received more than 60 ‘Letters Of Intent’. Through these, European research teams expressed their intention to submit proposals for new scientific missions and provided their preliminary concepts.

The mission concepts range from the exploration of Jupiter and its satellite Europa, to satellites studying radiation from the Big Bang and testing theories concerning the inflation of the Universe. The concepts also include missions studying near-Earth asteroids, satellites looking for liquid water on Saturn’s moon Enceladus and spacecraft to verify gravity as one of the fundamental forces.

On 29 June ESA will receive detailed missions proposals. Starting in October 2007, until mid-2009, ESA’s Space Science Advisory committee and scientific working groups will assess the proposals and pre-select three ‘class-M’ missions and three ‘class-L’ missions.

Class-M missions are medium-size projects, where the costs to ESA do not exceed 300 million euros. Class-L missions are larger projects, with cost envelopes not exceeding 650 million euros.

By the end of 2009, out of these three class-M and three class-L missions (plus LISA), two class-M and two class-L missions will further be short-listed for the definition phase (mission ‘phase A’). This phase will be run by European industries on a competitive basis between the beginning of 2010 and mid-2011.

By the end of 2011, one class-M and one class-L mission each will be adopted for implementation with launch foreseen in 2017 and 2018 respectively.

Image taken using Hubble's Wide Field & Planetary Camera 2 on Dec. 30, 1998 and June 17, 1999. Credits: NASA/ESA, J. English (U. of Manitoba), S. Hunsberger (PSU), Z. Levay ( STSI), S. Gallagher (PSU) and J. Charlton (PSU)
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Was Einstein Right?
Public Peek At Gravity Probe B Results from Science Daily
Where has all the antimatter gone? VELO from SciTech
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ESA's Darwin

Search For Extrasolar Planets And Extraterrestrial Life Improved With Darwin's Frictionless Optics

ESA's Darwin mission aims to discover extrasolar planets and examine their atmospheres for the presence of certain life-related chemicals such as oxygen and carbon dioxide.

The major technical challenge lies in distinguishing, or resolving, the light from an extrasolar planet from the hugely overwhelming radiation emitted by the planet's nearby star.
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The multi-satellite Darwin mission will use optical interferometry in which at least three separate orbiting telescopes jointly operate as an equivalent single telescope with a much larger effective aperture, thus achieving the required resolution. With this method, multiple smaller telescopes having actual apertures of, for example, 3 metres, can combine to provide an effective aperture of several tens to hundreds of metres, depending on the distance between the individual telescopes.

Creating delicate phase delays
Darwin will use nulling interferometry, a specific interferometric technique used to shield the overwhelming star emissions by precisely delaying the radiation coming from some of the telescopes by a small amount. This, in combination with achromatic - or colour independent - phase shifters, will cancel out the bright star radiation while allowing the much fainter extrasolar planet light to be detected.

A component known as an Optical Delay Line (ODL) is at the core of such interferometric observations. An ODL is a sophisticated opto-mechanical device that can introduce well-defined variations, or delays, in the optical path of a light beam and includes a moving mirror positioned with extremely good accuracy.

Precise movement using magnetic levitation
To demonstrate the critical technology required by Darwin, ESA's Technology Research Programme has sponsored the design and testing of an ODL that uses magnetic levitation for precise, frictionless mirror movement.

Sub-nanometre resolution to be incorporated in future flight mechanism
The ODL has also been thoroughly tested in Darwin's demanding cryogenic environment, at 40 Kelvin - or about -233 Celsius.

Darwin's ODLs are uniquely engineered to operate at cryogenic temperatures to avoid self-interference from the satellites' own thermal radiation. This is mandatory as Darwin will conduct observations at mid-infrared wavelengths, where the planet-to-starlight brightness ratio is relaxed compared to that in visible wavelengths, and where life-related marker chemicals such as water, ozone and carbon dioxide can be detected.

The ODLs will be used in Darwin for co-phasing the light collected by the separate telescopes within a central hub spacecraft, which is responsible for the correct recombination of the light beams and hence achieving the high-performance resolution of a single very large telescope.

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NASA Predicts Nongreen Plants On Other Planets
Deep Impact Mission: Aiming For Close-ups Of Extrasolar Planets
Searching for Other Planet Worlds from Centauri Dreams
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Space Tsunami

The image to the left is the typical appearance of the aurora before a magnetic substorm. During a substorm, the single auroral ribbon may split into several ribbons (centre) or even break into clusters that race north and south (right). Credits: Jan Curtis

Cluster provides new insights into the working of a ‘space tsunami’ that plays a role in disrupting the calm and beautiful aurora, or northern lights, creating patterns of auroral dances in the sky.

Generally seen in high-latitude regions such as Scandinavia or Canada, aurorae are colourful curtains of light that appear in the sky. Caused by the interaction of high-energy particles brought by the solar wind with Earth’s magnetic field, they appear in many different shapes.

Early in the evening, the aurora often forms a motionless green arc that stretches across the sky in the east-west direction. Colourful dancing auroral forms are the results of disturbances known as ‘substorms’ taking place in Earth’s magnetosphere.

These perturbations can affect our daily lives, in particular by affecting the reception of GPS signals. Thus, understanding the physical processes involved is important to our routine life and security.
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These substorms typically last one to two hours and are three-dimensional physical phenomena spread over altitudes from 100 to 150 000 kilometres.

Currently, there are two competing theoretical models to describe these substorms or space tsunamis. The first one is called the ‘Current-Disruption’ model, while the second one is the ‘Near Earth Neutral Line Model’. Using data from the four Cluster spacecraft, a group of scientists from both sides of the Atlantic were able to confirm that the behaviour of some substorms is consistent with the Current Disruption model.

In the late stage of substorm development, auroral disturbances move towards the poles, suggesting that the energy source for auroras and substorms moves away from Earth.

Previous satellite observations have found that, during this late stage, the flows of plasma (a gas of charged particles populating Earth’s magnetosphere) in the magnetotail exhibit a reversal in direction. In recent years it was generally thought that a flow reversal region is where magnetic reconnection takes place, that is where the energy of the magnetic field is converted into particle energy (dissipation effect), resulting in high-speed plasma flows that hurl towards Earth, like space tsunamis.

By comparing the directions of the electric current and the electric field in the magnetosphere it is possible to understand whether the cause of the flow reversal is a dissipation effect (where magnetic field energy converted to particle energy) or a dynamo effect (where particle energy is converted to magnetic field energy). For this case study, the Cluster scientists observed that features associated with flow reversal are actually very complex, consisting of both dissipation and dynamo effects in localised sites.

Read more: Cluster sees tsunamis in space from ESA

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