StarStuff

The Science Report

by Stuart Gary

Citizen science measures up

I’ve just written a story for ABC Science about citizen scientists helping solve a decades-old puzzle by assisting astronomers to make the most accurate distance measurements yet for an important star system.

The new research found the distance to the binary system SS Cygni in the constellation Cygnus the Swan, is 372 light-years.

That’s far closer than previous measurements of 520 light-years made by the Hubble Space Telescope.

The binary system consists of a white dwarf, which is the dead stellar corpse of a star that was once like the Sun.

It’s in orbit with a normal companion star of about half the Sun’s mass, known as an orange K class dwarf.

The system, known as a dwarf nova is used as a prototype by astronomers studying how accretion disks work around compact stellar objects from white dwarfs to more exotic things like neutron stars and black holes.

If you missed my radio report on the story and you want to find out more, check out the online version at:
http://www.abc.net.au/science/articles/2013/05/24/3766035.htm

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MOST DETAILED OBSERVATIONS EVER OF THE RING NEBULA

NASA’S Hubble Space Telescope Reveals the Ring Nebula’s True Shape WASHINGTON — 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.

“The nebula is not like a bagel, but rather, it’s like a jelly doughnut, because it’s filled with material in the middle,” said C. Robert O’Dell of Vanderbilt University in Nashville, Tenn. He leads a research team that used Hubble and several ground-based telescopes to obtain the best view yet of the iconic nebula. The images show a more complex structure than astronomers once thought and have allowed them to construct the most precise 3-D model of the nebula.

“With Hubble’s detail, we see a completely different shape than what’s been thought about historically for this classic nebula,” O’Dell said. “The new Hubble observations show the nebula in much clearer detail, and we see things are not as simple as we previously thought.”

The Ring Nebula is about 2,000 light-years from Earth and measures roughly 1 light-year across. Located in the constellation Lyra, the nebula is a popular target for amateur astronomers.

Previous observations by several telescopes had detected the gaseous material in the ring’s central region. But the new view by Hubble’s sharp-eyed Wide Field Camera 3 shows the nebula’s structure in more detail. O’Dell’s team suggests the ring wraps around a blue, football-shaped structure. Each end of the structure protrudes out of opposite sides of the ring.

The nebula is tilted toward Earth so that astronomers see the ring face-on. In the Hubble image, the blue structure is the glow of helium. Radiation from the white dwarf star, the white dot in the center of the ring, is exciting the helium to glow. The white dwarf is the stellar remnant of a sun-like star that has exhausted its hydrogen fuel and has shed its outer layers of gas to gravitationally collapse to a compact object.

O’Dell’s team was surprised at the detailed Hubble views of the dark, irregular knots of dense gas embedded along the inner rim of the ring, which look like spokes in a bicycle wheel. These gaseous tentacles formed when expanding hot gas pushed into cool gas ejected previously by the doomed star. The knots are more resistant to erosion by the wave of ultraviolet light unleashed by the star. The Hubble images have allowed the team to match up the knots with the spikes of light around the bright, main ring, which are a shadow effect. Astronomers have found similar knots in other planetary nebulae.

All of this gas was expelled by the central star about 4,000 years ago. The original star was several times more massive than our sun. After billions of years converting hydrogen to helium in its core, the star began to run out of fuel. It then ballooned in size, becoming a red giant. During this phase, the star shed its outer gaseous layers into space and began to collapse as fusion reactions began to die out. A gusher of ultraviolet light from the dying star energized the gas, making it glow.

The outer rings were formed when faster-moving gas slammed into slower-moving material. The nebula is expanding at more than 43,000 miles an hour, but the center is moving faster than the expansion of the main ring. O’Dell’s team measured the nebula’s expansion by comparing the new Hubble observations with Hubble studies made in 1998.

The Ring Nebula will continue to expand for another 10,000 years, a short phase in the lifetime of the star. The nebula will become fainter and fainter until it merges with the interstellar medium.

Studying the Ring Nebula’s fate will provide insight into the sun’s demise in another 6 billion years. The sun is less massive than the Ring Nebula’s progenitor star, so it will not have an opulent ending.

“When the sun becomes a white dwarf, it will heat more slowly after it ejects its outer gaseous layers,” O’Dell said. “The material will be farther away once it becomes hot enough to illuminate the gas. This larger distance means the sun’s nebula will be fainter because it is more extended.”

In the analysis, the research team also obtained images from the Large Binocular Telescope at the Mount Graham International Observatory in Arizona and spectroscopic data from the San Pedro Martir Observatory in Baja California, Mexico.

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Pavlof Volcano From Station

Astronauts aboard the International Space Station (ISS) photographed this striking view of Pavlof Volcano on May 18, 2013. The oblique perspective from the ISS reveals the three dimensional structure of the ash plume, which is often obscured by the top-down view of most remote sensing satellites.

Situated in the Aleutian Arc about 625 miles (1,000 kilometers) southwest of Anchorage, Pavlof began erupting on May 13, 2013. The volcano jetted lava into the air and spewed an ash cloud 20,000 feet (6,000 meters) high. When photograph ISS036-E-2105 (top) was taken, the space station was about 475 miles south-southeast of the volcano (49.1° North latitude, 157.4° West longitude). The volcanic plume extended southeastward over the North Pacific Ocean.

Image Credit: NASA

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A HIDDEN POPULATION OF EXOTIC NEUTRON STARS

Magnetars — the dense remains of dead stars that erupt sporadically with bursts of high-energy radiation — are some of the most extreme objects known in the universe. A major campaign using NASA’s Chandra X-ray Observatory and several other satellites shows magnetars may be more diverse — and common — than previously thought.

When a massive star runs out of fuel, its core collapses to form a neutron star, an ultradense object about 10 to 15 miles wide. The gravitational energy released in this process blows the outer layers away in a supernova explosion and leaves the neutron star behind.

Most neutron stars are spinning rapidly — a few times a second — but a small fraction have a relatively low spin rate of once every few seconds, while generating occasional large blasts of X-rays. Because the only plausible source for the energy emitted in these outbursts is the magnetic energy stored in the star, these objects are called “magnetars.”

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 observations show that the magnetar known as SGR 0418+5729 (SGR 0418 for short) doesn’t fit that pattern. It has a surface magnetic field similar to that of mainstream neutron stars.

“We have found that SGR 0418 has a much lower surface magnetic field than any other magnetar,” said Nanda Rea of the Institute of Space Science in Barcelona, Spain. “This has important consequences for how we think neutron stars evolve in time, and for our understanding of supernova explosions.”

The researchers monitored SGR 0418 for over three years using Chandra, ESA’s XMM-Newton as well as NASA’s Swift and RXTE satellites. They were able to make an accurate estimate of the strength of the external magnetic field by measuring how its rotation speed changes during an X-ray outburst. These outbursts are likely caused by fractures in the crust of the neutron star precipitated by the buildup of stress in a relatively strong, wound-up magnetic field lurking just beneath the surface.

“This low surface magnetic field makes this object an anomaly among anomalies,” said co-author GianLuca Israel of the National Institute of Astrophysics in Rome. “A magnetar is different from typical neutron stars, but SGR 0418 is different from other magnetars as well.”

By modeling the evolution of the cooling of the neutron star and its crust, as well as the gradual decay of its magnetic field, the researchers estimated that SGR 0418 is about 550,000 years old. This makes SGR 0418 older than most other magnetars, and this extended lifetime has probably allowed the surface magnetic field strength to decline over time. Because the crust weakened and the interior magnetic field is relatively strong, outbursts could still occur.

The case of SGR 0418 may mean that there are many more elderly magnetars with strong magnetic fields hidden under the surface, implying that their birth rate is five to ten times higher than previously thought.

“We think that about once a year in every galaxy a quiet neutron star should turn on with magnetar-like outbursts, according to our model for SGR 0418,” said Josè Pons of the University of Alacant in Spain. “We hope to find many more of these objects.”

Another implication of the model is that the surface magnetic field of SGR 0418 should have once been very strong at its birth a half million years ago. This, plus a possibly large population of similar objects, could mean that the massive progenitor stars already had strong magnetic fields, or these fields were created by rapidly rotating neutron stars in the core collapse that was part of the supernova event.

If large numbers of neutron stars are born with strong magnetic fields then a significant fraction of gamma-ray bursts might be caused by the formation of magnetars rather than black holes. Also, the contribution of magnetar births to gravitational wave signals — ripples in space-time — would be larger than previously thought.

The possibility of a relatively low surface magnetic field for SGR 0418 was first announced in 2010 by a team with some of the same members. However, the scientists at that time could only determine an upper limit for the magnetic field and not an actual estimate because not enough data had been collected.

SGR 0418 is located in the Milky Way galaxy at a distance of about 6,500 light-years from Earth. These new results on SGR 0418 appear online [http://arxiv.org/abs/1303.5579] and will be published in the June 10, 2013, issue of The Astrophysical Journal [http://apj.aas.org].

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

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Soyuz integration is fully underway for Arianespace’s milestone launch with four O3b Networks satellites

Soyuz Flight VS05

The Soyuz launcher for Arianespace’s next medium-lift mission is rapidly taking shape at French Guiana as this vehicle undergoes its build-up for a June flight with the first four satellites in O3b Networks’ connectivity constellation.

During activity this week in the Spaceport’s MIK launcher integration building for Soyuz, the vehicle’s core second stage was completed with the mating of its upper and lower sections. Today, team members installed two of Soyuz’ four first-stage boosters, which are clustered around the core stage.

These integration steps are performed with the Soyuz aligned in horizontal jigs positioned with the MIK facility’s floor-level rail system, and will be followed by mating of the launcher’s centerline third stage.

Once completed, the Soyuz will be ready for its rollout to the Spaceport’s ELS launch pad, where it will be raised to the vertical position – preparing it for integration of the O3b Networks satellite payload, performed with the protection of a 53-meter-tall mobile gantry.

The O3b Networks satellites to be orbited on Arianespace’s June 24 mission were built by Thales Alenia Space, and are to be positioned at a medium-Earth orbit altitude of 8,063 km. Operating in Ka-band, these spacecraft will become part of O3b Networks’ system that offers high-speed, low-cost, low-latency Internet and telecommunications services for customers in emerging markets.

This Soyuz flight will be Arianespace’s fifth with the medium-lift vehicle from the Spaceport since its introduction at French Guiana in October 2011. Soyuz is part of the company’s complete launcher family, which also includes the heavyweight Ariane 5 and light-lift Vega.

In addition to the first batch of O3b spacecraft to be lofted during the June mission, another Arianespace flight is scheduled to orbit four more later this year for O3b Networks, followed by an additional four in 2014.

IMAGE…The upper and lower segments of Soyuz’ core second stage are mated in the Spaceport’s MIK launcher integration building. The distinctive “hammerhead” shape enables Soyuz’ four second-stage boosters to be clustered around the core stage, as shown during the installation process.

spacettf:

Sh2-101 Tulip nebula in hubble palette by swag72 on Flickr.

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spacettf

letsbuildahome-fr:

Extreme Architecture

The Pont du Sart is a navigable aqueduct in the West of Belgium

(Source: thekhooll)

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conrailbrian

senior-crown:

Post #978 is dedicated to my favorite Blackbird, #978. She was one of the first SR-71’s to be flown over to Kadena AB in 1968. The Playboy bunny logo was painted on with Hugh Hefner’s permission, earning her the name “Rapid Rabbit”, only one of four Sleds with individual names. Unfortunately, she was lost on July 20, 1972 at Kadena after attempting to land under extreme crosswinds. One of her rudders, however, was salvaged and installed on #975. When #975 was put on display at the March Field Museum, the inside of the rudder was painted as #978. The next Blackbird loss did not occur until 17 years later, and it was the last. More info:

http://www.habu.org/sr-71/17978.html

http://www.wvi.com/~sr71webmaster/loss_4.htm

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conrailbrian

scott62568:

Here’s looking at you !!!!!

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conrailbrian

spaceplasma:

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)

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neuronsandneutrons

astronemma:

ESO’s Top 100 Images: 11-15

11. ESO’s VLT reveals the Carina Nebula’s hidden secrets (bottom). Credit: ESO/T. Preibisch

12. VST image of the giant globular cluster Omega Centauri (middle right). Credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: A. Grado/INAF-Capodimonte Observatory

13. Messier 78: a reflection nebula in Orion (middle left). Credit: ESO/Igor Chekalin

14. Panoramic view of the WR 22 and Eta Carinae regions of the Carina Nebula (middle). Credit: ESO

15. The hidden fires of the Flame Nebula (top). Credit: ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit

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understandingtheuniverse

npr:

This map shows just-released satellite imagery of the damage from the tornado that struck Moore, Okla., and vicinity on May 20 — one of the most destructive storms ever recorded. Zoom in to see the extent of the damage.

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npr

space-pics:

With Russian Meteor Fresh In Everyone’s Memory, ESA Opens An Asteroid Monitoring Center
http://space-pics.tumblr.com/

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space-pics

preachingtoinfinity:

spaceplasma:

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

Beautiful.

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understandingtheuniverse

astronemma:

ESO’s Top 100 Images: 1-5

1. VISTA’s infrared view of the Orion Nebula (top left). Credit: ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit

2. The Helix Nebula (bottom left). Credit: ESO

3. VST image of the star-forming region Messier 17 (bottom right). Credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute

4. A 340-million pixel starscape from Paranal (middle). Credit: ESO/S. Guisard

5. NGC 2264 and the Christmas Tree cluster (top right). Credit: ESO

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aimlessinspace

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