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Asteroid Spinning Itself to Death

A Hubble Space Telescope image revealing the gradual self-destruction of an asteroid, whose ejected dusty material...
A Hubble Space Telescope image revealing the gradual self-destruction of an asteroid, whose ejected dusty material has formed two long, thin, comet-like tails(Credit: NASA/ESA/K. Meech and J. Kleyna (University of Hawaii)/O. Hainaut (European Southern Observatory))

NASA has released images from the Hubble Space Telescope showing an asteroid that is tearing itself apart. Located 214 million mi (344 million km) from the Sun, the 2.5-mile-wide (4-km) asteroid (6478) Gault is spinning so fast that it is self-destructing and throwing off debris tails half a million miles (800,000 km) long. read more

Hubble reveals Horsehead Nebula

It is an astonishing new view of a unique  nebula.

Researchers have used NASA’s Hubble Space  Telescope to photograph the iconic Horsehead Nebula in a new, infrared light to  mark the 23rd anniversary of the famous observatory.

Looking like an apparition rising from whitecaps of interstellar foam, the iconic Horsehead Nebula has graced astronomy books ever since its discovery more than a century ago.

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The Horsehead Nebula as viewed at near-infrared wavelengthswith the NASA/ESA Hubble Space Telescope.
The Horsehead Nebula as viewed at near-infrared  wavelengthswith the NASA/ESA Hubble Space Telescope. This thick pillar of gas  and dust is sculpted by powerful stellar winds blowing from clusters of massive  stars located beyond the field of this image. The bright source at the top left  edge of the nebula is a young star whose radiation is already eroding the  surrounding interstellar material.

 

HUBBLE’S HISTORY

Hubble has been producing ground-breaking  science for two decades since its launch  aboard the space shuttle Discovery on April 24, 1990.

During that time, it has benefited from a  slew of upgrades from space shuttle  missions, including the 2009 addition of a  new imaging workhorse, the  high-resolution Wide Field Camera 3 that took the  new portrait of the  Horsehead.

 

The nebula is a favorite target for amateur  and professional astronomers.

It is shadowy in optical light, and appears  transparent and ethereal when seen at infrared wavelengths.

‘The rich tapestry of the Horsehead Nebula  pops out against the backdrop of Milky Way stars and distant galaxies that  easily are visible in infrared light,’ said Nasa.

The nebula is part of the Orion Molecular  Cloud, located about 1,500 light-years away in the constellation Orion.

The cloud also contains other well-known  objects such as the Great Orion Nebula (M42), the Flame Nebula, and Barnard’s  Loop.

It is one of the nearest and most easily  photographed regions in which massive stars are being formed.

Spot the horsehead:

A new view from ESA’s Herschel space  observatory of the iconic Horsehead Nebula in the context of its surroundings.  The Horsehead Nebula resides in the constellation Orion, about 1300 light-years  away, and is part of the vast Orion Molecular Cloud complex. To the left, the  panoramic view also covers two other prominent sites where massive stars are  forming, NGC 2068 and NGC 2071.

In the Hubble image, the backlit  wisps  along the Horsehead’s upper ridge are being illuminated by Sigma  Orionis, a  young five-star system just out of view.

Along the nebula’s top ridge, two fledgling  stars peek out from their now-exposed nurseries.

Scientists know a harsh ultraviolet glare  from one of these bright stars is slowly evaporating the nebula.

Gas clouds surrounding the Horsehead already  have dissipated, but the tip  of the jutting pillar contains a slightly higher  density of hydrogen and helium, laced with dust.

This casts a shadow that protects material  behind it from being stripped  away by intense stellar radiation evaporating the  hydrogen cloud, and a  pillar structure forms.

Hubble has been producing ground-breaking  science for two decades since its launch  aboard the space shuttle Discovery on April 24, 1990.

During that time, it has benefited from a  slew of upgrades from space shuttle missions, including the 2009 addition of a  new imaging workhorse, the high-resolution Wide Field Camera 3 that took the new  portrait of the Horsehead.

This three-panel image shows the latest near-infrared Hubble image of the Horsehead Nebula
This three-panel image shows the latest near-infrared  Hubble image of the Horsehead Nebula in context with the new wide-field Herschel  view of the surrounding

Attribution: Mark Prigg, Mail Online

Big Dipper Changing

The Universe is Alive

Image credit: NASA/ESA, The Hubble Key Project Team and The High-Z Supernova Search Team.

Image credit: NASA/ESA, The Hubble Key Project Team and The High-Z Supernova Search Team.
This image obtained by the Hubble Space Telescope shows the galaxy NGC 4526 and its supernova 1994D (lower left).

“Night, when words fade and things come alive. When the destructive analysis of day is done, and all that is truly important becomes whole and sound again.” –Antoine de Saint-Exupery

When you look out into the Universe, what is it that you typically think of? Do you think of reliable, fixed stars and constellations? The vast expanse of the Milky Way, with its memorable dust lanes and amorphous shapes?

Image credit: Wally Pacholka of http://www.astropics.com/.

Image credit: Wally Pacholka of http://www.astropics.com/.The unchanging nature of the points of light in the sky?Image credit: Roth Ritter (Dark Atmospheres), of the double cluster in Perseus.
Image credit: Roth Ritter (Dark Atmospheres), of the double cluster in Perseus.Maybe you think deeper and farther than that. Maybe you think about the distant galaxies and clusters, and the deepest deep-sky objects we know of. How the light took millions or even billions of years to reach us, and yet how every time we look at them, we see them exactly the same way.Image credit: Misti Mountain Observatory.
Image credit: Misti Mountain Observatory.I couldn’t fault you for thinking like this; from mankind’s point of view, the Universe — for all intents and purposes — doesn’t change at all as we view it from one night to the next.But does that really mean the Universe isn’t changing?Let me flip this around on you: how much does anything here on Earth — you, your surroundings, even an entire, vibrant city — change in half-a-millisecond?

Image credit: DC User Forum, of a short-exposure shot with a Sony A900 DSLR.

Image credit: DC User Forum, of a short-exposure shot with a Sony A900 DSLR.Not a whole lot, that’s for certain. You only change with the passage of time, and half-a-millisecond is just 0.00000000002% of a typical human lifetime. It’s too short of a timespan to notice any but the most catastrophic changes, and even then you have to look very closely.So why should you expect the Universe to change substantially over just 0.00000000002% of its lifetime? That’s how much of the Universe’s lifetime passes between one night on Earth and the next. And yet, if you looked at the right objects, you would be able to see meaningful changes from one night to the next.Image credit: Tunc Tezel.

Image credit: Tunc Tezel.The objects within our Solar System, for example, are close enough that we can see them moving from night-to-night. Objects closer to us — like Mars, in the foreground — appear to move more substantially than more distant objects like Uranus, visible in the background.The great cause of all this motion, of course, is our largest nearby clump of matter: the Sun. Objects like planets move at tens of kilometers-per-second relative to the Sun thanks to its gravity, while Sun-grazing comets can be accelerated up to speeds in the hundreds of kilometers-per-second. If you’re in the southern hemisphere, you may be able to get a good view of one now: Comet Lemmon.Image credit: Rolf Wahl Olsen from Auckland, New Zealand.

Image credit: Rolf Wahl Olsen from Auckland, New Zealand.Green because of the carbon and nitrogen interacting with sunlight, this photo does an excellent job of tracking the stars from the Earth along with the Earth’s rotation. What you probably can’t tell is that the comet — with a photo exposure time of over an hour — is blurred.If instead of tracking the stars perfectly, we tracked the comet perfectly, know what we’d see?Image credit: Peter Ward (Barden Ridge Observatory).

Image credit: Peter Ward (Barden Ridge Observatory)That comet is moving relative to the stars behind it, and our ultra-close proximity to the comet makes it abundantly clear.But what you may not realize is that these “fixed” stars are also moving at tens-to-hundreds of kilometers-per-second relative to us, and relative to one another! It’s only the vast distances between us — measured in many light-years — that make it impossible to detect these changes from night-to-night.But we can’t really detect changes in ourselves from millisecond-to-millisecond; you simply need to look on longer timescales!

Image credit: Martha Haynes of Cornell University.

Image credit: Martha Haynes of Cornell University.The stars in our night sky shift positions by many kilometers each second. From night-to-night we might not be able to tell the difference, but just as you or I look different when we go weeks without cutting our hair, we can see just how the Universe changes over long enough timescales.

There are gas clouds and stellar remnants tearing through the interstellar medium at these same speeds, including some that move at thousands of kilometers-per-second, even approaching 1% the speed of light!

Image credit: NASA/ESA/Hubble Heritage Team and CTIO.

Image credit: NASA/ESA/Hubble Heritage Team and CTIO.There are new stars being born — where nuclear fusion ignites for the first time — and stars that run out of fuel, dying in either a planetary nebula or a supernova explosion, depending on the properties of the star.Image credit: http://astrojan.ini.hu/, retrieved from Margaret Hanson, U. of Cincinnati.
Image credit: http://astrojan.ini.hu/, retrieved from Margaret Hanson, U. of Cincinnati.And on the largest scales, galaxies merge together, triggering star formation and some fabulous cosmic mashups, in processes taking upwards of hundreds-of-millions of years.Image credit: Hubble Space Telescope, NASA, STScI and ESA.
Image credit: Hubble Space Telescope, NASA, STScI and ESA.And in some of the fastest and most spectacular changes, catastrophic stellar events — like supernovae — can literally appear from nothing over the timescale of just a few nights!Image credit: Peter Nugent/Palomar Transient Factory.
Image credit: Peter Nugent/Palomar Transient Factory.When you look up at the Universe, it may appear static and unchanging, but that’s only because these objects are so far away and our human experiences are so short in comparison with the age of the Universe.But stick around for a while, and even the most mundane of objects will change for you. Fuel burns, elements fuse, gravity pulls, and physics happens. Just give it time, and you’ll see it for yourself.We may only be around for a snapshot of it, but make no mistake, it’s never the same from moment-to-moment. From the way I look at it, there isn’t any doubt about it: the Universe is alive.

Attribution: Ethan Siegel

Four Dwarfs of the Apocolypse

The shattered remains of planets that bear a striking resemblance to our own Earth have been found around white dwarf stars – offering a vision of what will one day happen to our planet.

University of Warwick astrophysicists found four white dwarves surrounded by the dust of shattered planets.

White dwarfs are the final stage of life of stars like our Sun – once the thermonuclear furnace inside a star ‘burns out’.

 Using the Hubble Space Telescope to carry out the biggest survey to date of the chemical composition of the atmospheres of white dwarf stars, the researchers found that the most frequently occurring elements in the dust around these four white dwarfs were oxygen, magnesium, iron and silicon — the four elements that make up roughly 93 percent of the Earth.

It’s evidence that the small, dense stars are surrounded by the ‘corpses’ of worlds they’ve ‘eaten’.

At least one of the stars is in the process of sucking in the planet’s core – rich in iron, nickel and sulphur – at a rate of around a million kilos a second. 

Professor Boris Gänsicke of the Department of Physics at the University of Warwick, who led the study, said the destructive process which caused the discs of dust around these distant white dwarfs is likely to one day play out in our own solar system.

‘What we are seeing today in these white dwarfs several hundred light-years away could well be a snapshot of the very distant future of the Earth.

‘As stars like our Sun reach the end of their life, they expand to become red giants when the nuclear fuel in their cores is depleted.

‘When this happens in our own solar system, billions of years from now, the Sun will engulf the inner planets Mercury and Venus. It’s unclear whether the Earth will also be swallowed up by the Sun in its red giant phase — but even if it survives, its surface will be roasted.

‘During the transformation of the Sun into a white dwarf, it will lose a large amount of mass, and all the planets will move further out. This may destabilize the orbits and lead to collisions between planetary bodies as happened in the unstable early days of our solar system.

‘This may even shatter entire terrestrial planets, forming large amounts of asteroids, some of which will have chemical compositions similar to those of the planetary core. In our solar system, Jupiter will survive the late evolution of the Sun unscathed, and scatter asteroids, new or old, towards the white dwarf.

However an even more significant observation was that this material also contained an extremely low proportion of carbon, which matched very closely that of the Earth and the other rocky planets orbiting closest to our own Sun.

This is the first time that such low proportions of carbon have been measured in the atmospheres of white dwarf stars polluted by debris.

This clear evidence that these stars once had at least one rocky exoplanet which they have now destroyed, the observations must also pinpoint the last phase of the death of these worlds.

The atmosphere of a white dwarf is made up of hydrogen and/or helium, so any heavy elements that come into their atmosphere are dragged downwards to their core and out of sight within a matter of days by the dwarf’s high gravity.

Given this, the astronomers must literally be observing the final phase of the death of these worlds as the material rains down on the stars at rates of up to 1 million kilograms every second.

Not only is this clear evidence that these stars once had rocky exoplanetary bodies which have now been destroyed, the observations of one particular white dwarf, PG0843+516, may also tell the story of the destruction of these worlds.

This star stood out from the rest owing to the relative overabundance of the elements iron, nickel and sulphur in the dust found in its atmosphere. Iron and nickel are found in the cores of terrestrial planets, as they sink to the center owing to the pull of gravity during planetary formation, and so does sulphur thanks to its chemical affinity to iron.
Therefore, researchers believe they are observing White Dwarf PG0843+516 in the very act of swallowing up material from the core of a rocky planet that was large enough to undergo differentiation, similar to the process that separated the core and the mantle of the Earth.

The University of Warwick led team surveyed more than 80 white dwarfs within a few hundred light-years of the Sun, using the Cosmic Origins Spectrograph onboard the Hubble Space Telescope.

This Month in Space

A supernova remnant 170,000 light years away in one of the Milky Way’s galactic neighbors. This image, taken by the Hubble Space Telescope, shows ambient gas being shocked by the expanding blast wave from the exploding star

Sand dunes trapped in an impact crater in the Noachis Terra region of Mars. The area covered in the image is about 1km (1100 yards) across. Sand dunes are among the most widespread wind-formed features on Mars. Patterns of dune erosion and deposition provide insights into the sedimentary history of the surrounding terrain. This picture is from the High Resolution Imaging Science Experiment (HiRISE) camera on board the Mars Reconnaissance Orbiter

This panoramic image taken from the International Space Station shows lights from population centers in Belgium and the Netherlands (center bottom), the British Isles partially obscured by solar array panels (left), the North Sea (center left), and Scandinavia (right) behind the space station’s remote manipulator system

Nasa captured this dramatic image of a solar flare on 2 January. To view a video of the event click here. The show lasted about three hours, but the blast was not directed at Earth

Solar flares on 23 January enhanced the aurora borealis in the skies over the frozen Susitna River near Talkeetna, in Alaska