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A Hidden Population of Exotic Neutron Stars A magnetar called...

Thu, 23 May 2013 18:21:43 +0300

A Hidden Population of Exotic Neutron Stars

A magnetar called SGR 0418+5729 (SGR 0418 for short) has been shown to have the lowest surface magnetic field ever found for this type of neutron star.

This graphic shows an exotic object in our galaxy called SGR 0418+5729 (SGR 0418 for short). As described in our press release, SGR 0418 is a magnetar, a type of neutron star that has a relatively slow spin rate and generates occasional large blasts of X-rays.

The only plausible source for the energy emitted in these outbursts is the magnetic energy stored in the star. Most magnetars have extremely high magnetic fields on their surface that are ten to a thousand times stronger than for the average neutron star. New data shows that SGR 0418 doesn’t fit that pattern. It has a surface magnetic field similar to that of mainstream neutron stars.

In the image above, data from NASA’s Chandra X-ray Observatory shows SGR 0418 as a pink source in the middle. Optical data from the William Herschel telescope in La Palma and infrared data from NASA’s Spitzer Space Telescope are shown in red, green and blue.

Below, an artist’s impression showing a close-up view of SGR 0418. This illustration highlights the weak surface magnetic field of the magnetar, and the relatively strong, wound-up magnetic field lurking in the hotter interior of the star. The X-ray emission seen with Chandra comes from a small hot spot, not shown in the illustration. At the end of the outburst this spot has a radius of only about 160 meters, compared with a radius for the whole star of about 12 km.

Full Article

Credit: X-ray: NASA/CXC/CSIC-IEEC/N.Rea et al; Optical: Isaac Newton Group of Telescopes, La Palma/WHT; Infrared: NASA/JPL-Caltech

Hubble reveals the Ring Nebula’s true shape In this composite...

Thu, 23 May 2013 18:04:00 +0300

Hubble reveals the Ring Nebula’s true shape

In this composite image, visible-light observations by NASA’s Hubble Space Telescope are combined with infrared data from the ground-based Large Binocular Telescope in Arizona to assemble a dramatic view of the well-known Ring Nebula.

The Ring Nebula’s distinctive shape makes it a popular illustration for astronomy books. But new observations by NASA’s Hubble Space Telescope of the glowing gas shroud around an old, dying, sun-like star reveal a new twist.

Full Article

Credit: NASA, ESA, C.R. Robert O’Dell (Vanderbilt University), G.J. Ferland (University of Kentucky), W.J. Henney and M. Peimbert (National Autonomous University of Mexico)

This “lightbulb” Coronal Mass Ejection (CME) shows...

Thu, 23 May 2013 17:59:19 +0300

This “lightbulb” Coronal Mass Ejection (CME) shows the three classical parts of a CME: leading edge, void, and core. In coronagraph images, direct sunlight is blocked by an occulter, revealing the surrounding faint corona. The approximate size of the Sun is represented by the white circle. Taken on February 27, 2000 by the LASCO C3 coronagraph.

Credit: SOHO (ESA & NASA)

The Very Large Telescope Snaps a Stellar Nursery and Celebrates...

Thu, 23 May 2013 17:54:10 +0300

The Very Large Telescope Snaps a Stellar Nursery and Celebrates Fifteen Years of Operations

This intriguing new view of a spectacular stellar nursery IC 2944 is being released to celebrate a milestone: 15 years of ESO’s Very Large Telescope. This image also shows a group of thick clouds of dust known as the Thackeray globules silhouetted against the pale pink glowing gas of the nebula. These globules are under fierce bombardment from the ultraviolet radiation from nearby hot young stars. They are both being eroded away and also fragmenting, rather like lumps of butter dropped onto a hot frying pan. It is likely that Thackeray’s globules will be destroyed before they can collapse and form new stars.

Credit: ESO

pappubahry: The comet Hartley 2, photographed by Deep Impact as...

Thu, 23 May 2013 15:08:39 +0300

pappubahry:

The comet Hartley 2, photographed by Deep Impact as part of its extended EPOXI mission, 4 November 2011.

The original photos from this encounter were blurry (I’ve uploaded an almost equivalent gif here for comparison) because of a problem with the lens. By pointing the camera at a star, effectively a point-source of light, and studying the precise way in which the point got blurred, the EPOXI team was able to work backwards and “deconvolve” the photos of Hartley 2. This procedure makes them much sharper, but also introduces some ringing artefacts, which are especially visible in the first few frames.

Unrolling Household Tape Produces X-Rays If you have ever (for...

Wed, 22 May 2013 20:14:27 +0300

Unrolling Household Tape Produces X-Rays

If you have ever (for whatever reason – that’s none of our business) locked yourself in a dark closet and peeled Scotch tape from its holder, you may have noticed a tiny bit of light. The tape actually emits a faint luminescence when it’s being separated. It’s due to a phenomenon known as triboluminescence, which has been documented as far back as the 17th century. In the 1950s, Soviet researchers claimed that unrolling sticky tape resulted also in the release of X-rays, but no one really bothered to follow up on that study until now.

A group of researchers at UCLA decided to test the X-ray claims recently. Using a machine to unroll the tape at 3 centimeters/second in a vacuum, they measured the electromagnetic output. The short bursts of X-rays lasted for about a billionth of a second each and output 300,000 X-ray photons. The researchers were even able to prove the presence of the X-rays by producing pictures of their finger bones. There’s no need to worry about getting a super-dose of radiation while taping the paper on birthday presents, though; the phenomenon seems to work only when the tape is in a vacuum.

The applications for this new knowledge are kind of sketchy at this point. The research team thinks that it may be useful for making cheaper X-ray machines or even for aiding in nuclear fusion. Both seem a little far-fetched, but harnessing this little-understood physical phenomenon may even create new, unforeseen possibilities in the future.

Powerful x-rays made from sticky tape [ video ]

Sonoluminescence: How Bubbles Turn Sound into...

Wed, 22 May 2013 18:42:42 +0300

Sonoluminescence: How Bubbles Turn Sound into Light

Sonoluminescence is a phenomenon that occurs when a small gas bubble is acoustically suspended and periodically driven in a liquid solution at ultrasonic frequencies, resulting in bubble collapse, cavitation, and light emission. The thermal energy that is released from the bubble collapse is so great that it can cause weak light emission. The mechanism of the light emission remains uncertain, but some of the current theories, which are categorized under either thermal or electrical processes, are Bremsstrahlung radiation, argon rectification hypothesis., and hot spot. People are beginning to lean more towards thermal processes as temperatures have consistently been proven with different methods of spectral analysis. In order to understand the light emission mechanism, it is important to know what is happening in the bubble’s interior and at the bubble’s surface.

The inertia of a collapsing bubble generates high pressures and temperatures capable of ionizing a small fraction of the noble gas within the volume of the bubble. This small fraction of ionized gas is transparent and allows for volume emission to be detected. Free electrons from the ionized noble gas begin to interact with other neutral atoms causing thermal bremsstrahlung radiation. Surface emission emits a more intense flash of light with a longer duration and is dependent on wavelength. Experimental data suggest that only volume emission occurs in the case of sonoluminescence. As the sound wave reaches a low energy trough the bubble expands and electrons are able to recombine with free ions and halt light emission. Light pulse time is dependent on the ionization energy of the noble gas with argon having a light pulse of 160 picoseconds.

Although the bubble above is illuminated with a floodlight that is shining directly into the camera the flash of light – sonoluminescence is easily seen as the bubble reaches its minimum radius.

Watch the video: here

Credit: Seth Putterman

Ternary Flame This image shows a ternary flame system with a...

Wed, 22 May 2013 17:27:00 +0300

Ternary Flame

This image shows a ternary flame system with a Santoro burner below a ring burner. The steady soot column generated by the acetylene diffusion flame passes into the hydrogen ring flame, where it is oxidized. This allows soot oxidation to be studied in the absence of soot formation. The camera is a Nikon D100 digital still camera at 6.1 megapixels. This research is supported by NSF.

Credit: H. Guo, P.M. Anderson, P.B. Sunderland (University of Maryland)

Spherical Ethylene Diffusion Flame in Microgravity This is an...

Wed, 22 May 2013 17:14:00 +0300

Spherical Ethylene Diffusion Flame in Microgravity

This is an image of a spherical diffusion flame of ethylene burning in air in the NASA GRC 2.2 s drop tower. The image was recorded about 1.4 s after ignition. The ethylene flowrate is 1.5 mg/s and the scale is revealed by the 6.5 mm porous sphere visible in the image. The image was recorded using a Nikon D100 digital single-lens reflex camera with a 125 ms exposure.

Credit: P.B. Sunderland (University of Maryland), D.L. Urban and D.P. Stocker (NASA Glenn Research Center), B.H. Chao (University of Hawaii) and R.L. Axelbaum (Washington University)

Centerbody Flames The images shown are photographs of...

Wed, 22 May 2013 17:10:00 +0300

Centerbody Flames

The images shown are photographs of ethylene/air/nitrogen diffusion flames stabilized behind a bluff centerbody. The two images on the top show the centerbody flame photographed from the side (top left) and top views (top right). The blue regions are associated with the flame front and the other colors of the flame are largely due to blackbody radiation from the soot. The intense yellow radiation is from soot trapped in a tight ring vortex downstream of the stabilizing bluff body. The motion of the soot trapped in the vortex can be seen in the longer exposure photograph taken from the top.

The bottom two images are of a centerbody flame with the same inlet flow velocities as the case shown above but with higher nitrogen content in the feed gases. The image on the lower left shows a blue ring flame that forms around the main flame immediately downstream of the centerbody. This blue ring flame exhibits a slight oscillation in the vertical direction. The image on the lower right shows the region downstream of the ring flame for the same conditions. The disturbances in the downstream region of the flame are amplified as it passes through the tube, resulting in the large structures shown in the short exposure (0.8 ms) photo.

Credit: Scott Stouffer, Garth Justinger (University of Dayton Research Institute), Mel Roquemore, Amy Lynch, Vince Belovich, Joe Zelina, Jim Gord (Air Force Research Laboratory, Wright Patterson Air Force Base), Keith Grinstead, Vish Katta and Kyle Frische (Innovative Scientific Solutions Incorporated)

An Expanding Bubble in Space A star 40 times more massive than...

Wed, 22 May 2013 16:32:28 +0300

An Expanding Bubble in Space

A star 40 times more massive than our sun is blowing a giant bubble of material into space. In this colorful picture, the Hubble Telescope captured a glimpse of the expanding bubble, dubbed the Bubble Nebula (NGC 7635). The beefy star [lower center] is embedded in the bright blue bubble. The stellar powerhouse is so hot that it is quickly shedding material into space. The dense gas surrounding the star is shaping the castoff material into a bubble. The bubble’s surface is not smooth like a soap bubble’s. Its rippled appearance is due to encounters with gases of different thickness. The nebula is 6 light-years wide and is expanding at 4 million miles per hour (7 million kilometers per hour). The nebula is 7,100 light-years from Earth in the constellation Cassiopeia.

Image Credit: NASA, Donald Walter (South Carolina State University), Paul Scowen and Brian Moore (Arizona State University)

Cassini’s Private Eclipse For this movie, Cassini pointed...

Mon, 20 May 2013 11:57:08 +0300

Cassini’s Private Eclipse

For this movie, Cassini pointed its cameras toward Dione to witness its distant sibling moon Rhea briefly pass behind in a series of 32 individual frames taken over 17 minutes. Four individual frames from the eclipse are shown at bottom.

Rhea (1,528 kilometers, 949 miles across) is larger than Dione (1,123 kilometers, 698 miles across), but also is farther away as seen here – thus, the two moons appear to be roughly the same angular size.

The view shows principally the anti-Saturn side of Dione, and the Saturn-facing side of far-off Rhea.

Credit: NASA/JPL/Space Science Institute

Mimas Occults Janus Icy, impact-riddled Mimas (396 kilometers,...

Mon, 20 May 2013 11:45:00 +0300

Mimas Occults Janus

Icy, impact-riddled Mimas (396 kilometers, 246 miles across) slips briefly in front of the moon Janus (179 kilometers, 111 miles across) in this movie from Cassini.

The movie was created from 37 original images taken over the course of 20 minutes as the spacecraft’s narrow angle camera remained pointed toward Janus. Although Mimas moves a greater distance across the field of view, Janus also moved perceptibly during this time. The images were aligned to keep Janus close to the center of the scene. Additional frames were inserted between the 37 Cassini images in order to smooth the appearance of Mimas’ movement – a scheme called interpolation. Close-up images from the few minutes surrounding the occultation are arranged into a strip along the bottom of the GIF.

The terrain on Mimas seen here is about 80 degrees to the west of that visible in a previously released movie, which showed the little moon appearing to cross Saturn’s ring plane from Cassini’s vantage point. In that previous movie, the rim of the large impact crater Herschel (130 kilometers, 80 miles wide) was visible as a flattening of the moon’s eastern limb. In the new movie, Herschel is almost at dead center.

Contrast on Janus was mildly enhanced to aid the visibility of its surface. The right side of Mimas appears bright because the moon was partly overexposed in this image sequence.

Credit: NASA/JPL/Space Science Institute

Intense Color on Rhea This intense false-color view highlights...

Mon, 20 May 2013 11:29:03 +0300

Intense Color on Rhea

This intense false-color view highlights and enhances color variations across the intensely cratered and cracked surface of Rhea.

To create the false-color view, ultraviolet, green and infrared images were combined into a single black and white picture that isolates and maps regional color differences. This “color map” was then superposed over a clear-filter image. The origin of the color differences is not yet understood, but may be caused by subtle differences in the surface composition or the sizes of grains making up the icy soil.

Wispy markings were seen on the trailing hemispheres of both Rhea and Dione in images taken by the Voyager spacecraft, and were hypothesized by some researchers to be the result of material extruded onto the surface by ice volcanism. Cassini’s earlier revelation of the braided fractures on Dione led to speculation that Rhea’s wisps might also be created by fractures.

Credit: NASA/JPL/Space Science Institute

Deep Space Station 35 Being Installed An animation, captured...

Mon, 20 May 2013 11:19:47 +0300

Deep Space Station 35 Being Installed

An animation, captured from a live webcam, of the Deep Space Station (DSS) 35 antenna being installed in Canberra, Australia. Located at the Canberra Deep Space Communication Complex, the 125 tonne parabolic dish was lifted into position on top of the antenna base structure for our newest antenna, Deep Space Station 35. Several webcams caught the action.

The Canberra DSN on Youtube

NASA / Assembled by Bill Dunford

Black-body radiation When astronomers refer to the temperature...

Sun, 19 May 2013 22:43:00 +0300

Black-body radiation

When astronomers refer to the temperature of a star, they are talking about the temperature of the gases in the photosphere, and they express those temperatures on the Kelvin temperature scale. On this scale, zero degrees Kelvin (written 0 K) is absolute (-273.2°C or -459.7°F), the temperature at which an object contains no thermal energy that can be extracted. Water freezes at 273 K and boils at 373 K (at sea-level atmospheric pressure). The Kelvin temperature scale is useful in astronomy because it is based on absolute zero and consequently is related directly to the motion of the particles in an object.

Now you can understand why a hot object glows, or to put it another way, why a hot object emits photons, bundles of electromagnetic energy. The hotter an object is, the more motion there is among its particles. The agitated particles, including electrons, collide with each other, and when electrons accelerate—change their motion—part of the energy is carried away as electromagnetic radiation. The radiation emitted by a heated object is called black-body radiation, a name translated from a German term that refers to the way a perfectly opaque object would behave. A perfectly opaque object would be both a perfectly efficient absorber and a perfectly efficient emitter of radiation. At room temperature, such a perfect absorber and emitter would look black, but at higher temperatures it would glow at wavelengths visible to a human eye. That explains why in astronomy and physics contexts you will see the term black-body referring to objects that glow brightly.

Black-body radiation is quite common. In fact, it is responsible for the light emitted by an incandescent light bulb. Electricity flowing through the filament of the bulb heats it to high temperature, and it glows. You can also recognize the light emitted by hot lava as black-body radiation. Many objects in the sky, including the sun and other stars, primarily emit black-body radiation because they are mostly opaque.

Credit: Michael A. Seeds, Dana E. Backman (Horizons: Exploring the Universe)

Gif credit: caucasianmale

Zodiacal Light and Milky Way This animated gif is only a very...

Sun, 19 May 2013 20:53:14 +0300

Zodiacal Light and Milky Way

This animated gif is only a very rough preview of a time lapse movie made from individual images taken on a tripod with a Canon 20Da camera and a 15mm lens.

The movie is available in different formats and sizes: here

Credit: Stéphane Guisard, Valère Leroy and Jean Pajus

A Burning Candle In Zero-Gravity The results of a Burning and...

Sun, 19 May 2013 15:57:00 +0300

A Burning Candle In Zero-Gravity

The results of a Burning and Suppression of Solids (BASS) experiment demonstrates that in zero-gravity—where heat doesn’t rise—a flame burns in a uniform oval.

Credit: Col. Chris Hadfield

Music for Stargazing: Stars of the Lid - The Tired Sounds of...

Sun, 19 May 2013 15:06:33 +0300

Music for Stargazing:

Stars of the Lid - The Tired Sounds of Stars of the Lid

Barnard Stares at NGC 2170 A gaze across a cosmic...

Sun, 19 May 2013 14:43:00 +0300

Barnard Stares at NGC 2170

A gaze across a cosmic skyscape, this telescopic mosaic reveals the continuous beauty of things that are. The evocative scene spans some 6 degrees or 12 Full Moons in planet Earth’s sky. Above, folds of red, glowing gas are a small part of an immense, 300 light-year wide arc. Known as Barnard’s loop, the structure is too faint to be seen with the eye, shaped by long gone supernova explosions and the winds from massive stars, and still traced by the light of hydrogen atoms. Barnard’s loop lies about 1,500 light-years away roughly centered on the Great Orion Nebula, a stellar nursery along the edge of Orion’s molecular clouds. But beyond lie other fertile star fields in the plane of our Milky Way Galaxy. Below, the long-exposure composite finds NGC 2170, a dusty complex of nebulae near a neighboring molecular cloud some 2,400 light-years distant.