NASA Spitzer Image: Star-forming region ON2

Massive stars are born in tumultuous clouds of gas and dust.

They lead a brief but intense life, blowing powerful winds of particles and radiation that strike their surroundings, before their explosive demise as supernovas.

The interplay between massive stars and their environment is revealed in this image of the star-forming region ON2.

It combines X-ray coverage from ESA’s XMM-Newton X-ray observatory with an infrared view from NASA’s Spitzer Space Telescope.

This stellar cradle is associated with the open cluster of stars named Berkeley 87, some 4000 light-years from Earth.

The cluster is home to over 2000 stars, most of which are low-mass stars like our Sun or smaller, but some, a few dozen, are stellar monsters weighing 10–80 times more.

Two glowing clouds of gas and dust, the raw material from which stars form, dominate the centre of the image and are shown in red.

Scattered across the image are a multitude of protostars, seeds of future stellar generations; these are shown in green.

The bright yellow star in the upper part of the image is BC Cygni, a massive star that has puffed up enormously and will eventually explode as a supernova.

Shown in blue is XMM-Newton X-ray view of ON2: it reveals individual sources, young, massive stars as well as protostars, and more diffuse regions of X-rays.

Two ‘bubbles’ of X-rays can be seen in the upper and lower clouds, respectively, pink against the red background.

These two bubbles conceal the cumulative emissions from many protostars, but also light radiated by very energetic particles, a signature of shockwaves triggered by massive stars and their winds.

The image combines observations performed in the X-ray energy range of 0.25–12 keV (blue) and at infrared wavelengths of 3.6 microns (green) and 8 microns (red).

It spans about 15 arcminutes on each side; north is up and east is to the left.

More Information:  paper “Hard X-Ray Emission in the Star-Forming Region ON 2: Discovery with XMM-Newton” by Oskinova et al. in April 2010.

ESA XMM-Newton X-ray Image: A magnetic monster’s dual personality

Click on the Image to watch an animation.

Is it a magnetar or is it a pulsar? A second member of a rare breed of dead, spinning star has been identified thanks to an armada of space-based X-ray telescopes, including ESA’s XMM-Newton.

Its curious behaviour is illustrated in this animation.

Magnetars are a type of neutron star, the dead cores of massive stars that have collapsed in on themselves after burning up all their fuel and exploding as dramatic supernovas.

They typically display bright, persistent X-ray emission and the most intense magnetic fields known in the Universe.

Pulsars meanwhile are spinning neutron stars with much lower magnetic fields than magnetars that appear to pulse radio waves as they rotate rapidly.

The pulses are seen when beams of radiation rotate through our line of sight from Earth, rather like the sweeping beam of a lighthouse.

The recently discovered star appears to be a hybrid of these two stellar breeds: the spinning stellar skeleton appears as a pulsar while hiding an intense internal magnetic field much like a magnetar.

The internal field is many times stronger than its external magnetic field, leading to its entry into the new class of ‘low-field magnetars’.

As this animation illustrates, the turbulent interior arises as a result of twisted magnetic field lines.

As the field lines unwind, energy is released as a steady burst of X-rays through fractures in the star’s ‘crust’.

Only two examples of low-field magnetars are known. The first was discovered in 2010 and the second in July 2011, given away by short X-ray bursts that were detected by NASA’s Swift space telescope.

NASA’s Rossi X-Ray Timing Explorer and Chandra X-ray Observatory, ESA’s XMM-Newton and Japan’s Suzaku satellite, as well as the ground-based Gran Telescopio Canarias and the Green Bank Telescope, were alerted and the star’s activity was monitored until April 2012, during which time the outburst began to decay.

The discovery of a second member of this rare family of star strengthens the idea that magnetar-like behaviour may be much more widespread than believed in the past.

ESA XMM-Newton: X-ray satellite's breakthrough in mapping black holes

A veteran space telescope observing with X-ray eyes has made a breakthrough in helping to understand the supermassive black holes at the centre of galaxies.

Astronomers using the European Space Agency's (ESA) XMM-Newton satellite identified an "echo" within the galaxy NGC 4151, 45 million light-years away in the constellation of Canes Venatici, that they had long been searching for.

Galaxies such as NGC 4151 are known as active galaxies because they have brilliant centres which emit billions of times more energy than the Sun. These are lit up by material streaming in to a spinning monster black hole containing the mass of millions of stars.

A signature of these cosmic cannibals is a broad line in the X-ray region of the spectrum caused by excited and highly energetic iron atoms. This radiation is produced when a mystery X-ray source shines onto the whirling disk of matter spilling into the black hole, known as the accretion disk.

Astronomers know that these X-ray sources flare and they predicted that when this happened the broad iron line would brighten too after an interval depending on how long the X-rays took to light up the accretion disk in that strange physical environment.

Sadly these echoes of the flares were each too weak for XMM-Newton or NASA's powerful X-ray telescope Chandra to see individually. But an international team led by Dr Abderahmen Zoghbi, of the University of Maryland in the US, realised that if they could combine the echoes from several flares, then these might then become detectable.

They tested their theory using data from NGC 4151 which has an active nucleus powered by a black hole 50 million times the mass of the Sun. The galaxy's accretion disk was thought to be capable of producing more easily detectable echoes that would reverberate for a particularly long time.

An artist's impression of XMM-Newton in orbit. Credit: ESA

XMM-Newton has observed the galaxy extensively since the year 2000, building up the X-ray equivalent of a four-day photographic exposure. This has revealed numerous echoes, proving the astronomers' technique.

It allowed them to calculate that the X-ray source must lie around 640,000 km (400 million miles) above the supermassive black hole's accretion disk. Despite the black hole's incredible mass, that event horizon lies only half as far from it as the Earth's distance from the Sun. The team's work is published in the Monthly Notices of the Royal Astronomical Society.

Dr Zoghbi said: "Our analysis confirms some long-held ideas about active galactic nuclei and gives us a sense of what we can expect when a new generation of space-based X-ray telescopes eventually becomes available."

NASA's newest X-ray telescope, NuSTAR, is due to launch later this month from the Kwajalein Atoll in the central Pacific Ocean and is expected to study black holes in greater detail than ever.

ESA XMM Newton X-Ray Image: Galaxy NGC 4151

Credit: David W. Hogg, Michael R. Blanton, and the Sloan Digital Sky Survey Collaboration

This image shows the spiral galaxy NGC 4151, located at a distance of about 45 million light years from us.

NGC 4151 is a Seyfert galaxy and hosts one of the brightest active galactic nuclei (AGN) known at X-ray wavelengths.

The supermassive black hole lying at the centre of NGC 4151 has a mass of about 50 million solar masses.

Observations performed with ESA's XMM-Newton X-ray observatory have revealed X-rays emitted and then reflected by ionised iron atoms very close to the central black hole.

By measuring the time delays occurring in these 'reverberation' events, scientists have been able to map the vicinity of a black hole in unprecedented detail.

Ultra-fast Outflows Help Monster Black Holes Shape Their Galaxies

The supermassive black holes in active galaxies can produce narrow particle jets (orange) and wider streams of gas (blue-gray) known as ultra-fast outflows, which are powerful enough to regulate both star formation in the wider galaxy and the growth of the black hole.

Inset: A close-up of the black hole and its accretion disk. (Artist concept credit: ESA/AOES Medialab)

A curious correlation between the mass of a galaxy's central black hole and the velocity of stars in a vast, roughly spherical structure known as its bulge has puzzled astronomers for years.

An international team led by Francesco Tombesi at NASA's Goddard Space Flight Center in Greenbelt, Md., now has identified a new type of black-hole-driven outflow that appears to be both powerful enough and common enough to explain this link.

Most big galaxies contain a central black hole weighing millions of times the sun's mass, but galaxies hosting more massive black holes also possess bulges that contain, on average, faster-moving stars.

This link suggested some sort of feedback mechanism between a galaxy's black hole and its star-formation processes.

Yet there was no adequate explanation for how a monster black hole's activity, which strongly affects a region several times larger than our solar system, could influence a galaxy's bulge, which encompasses regions roughly a million times larger.

"This was a real conundrum. Everything was pointing to supermassive black holes as somehow driving this connection, but only now are we beginning to understand how they do it," Tombesi said.

Active black holes acquire their power by gradually accreting -- or "feeding" on -- million-degree gas stored in a vast surrounding disk. This hot disk lies within a corona of energetic particles, and while both are strong X-ray sources, this emission cannot account for galaxy-wide properties.

Near the inner edge of the disk, a fraction of the matter orbiting a black hole often is redirected into an outward particle jet. Although these jets can hurl matter at half the speed of light, computer simulations show that they remain narrow and deposit most of their energy far beyond the galaxy's star-forming regions.

Astronomers suspected they were missing something. Over the last decade, evidence for a new type of black-hole-driven outflow has emerged.

At the centers of some active galaxies, X-ray observations at wavelengths corresponding to those of fluorescent iron show that this radiation is being absorbed.

This means that clouds of cooler gas must lie in front of the X-ray source. What's more, these absorbed spectral lines are displaced from their normal positions to shorter wavelengths that is, blueshifted, which indicates that the clouds are moving toward us.

ESA Herschel & XMM-Newton Image: The Andromeda Galaxy

The Andromeda Galaxy is our nearest large galactic neighbour, containing several hundred billion stars. Combined, these images show all stages of the stellar life cycle.

The infrared image from Herschel shows areas of cool dust that trace reservoirs of gas in which forming stars are embedded.

The optical image shows adult stars. XMM-Newton's X-ray image shows the violent endpoints of stellar evolution, in which individual stars explode or pairs of stars pull each other to pieces.

Credits: infrared: ESA/Herschel/PACS/SPIRE/J. Fritz, U. Gent; X-ray: ESA/XMM-Newton/EPIC/W. Pietsch, MPE; optical: R. Gendler

NASA Chandra and ESA XMM-Newton Images: Rotating Neutron Star

Observations with NASA's Chandra, Swift, and Rossi X-ray observatories, Fermi Gamma-ray Space Telescope, and ESA's XMM-Newton have revealed that a slowly rotating neutron star with an ordinary surface magnetic field is giving off bursts of X-rays and gamma rays.

This discovery may indicate the presence of an internal magnetic field much more intense than the surface magnetic field, with implications for how the most powerful magnets in the cosmos evolve.

The neutron star, SGR 0418+5729, was discovered on June 5, 2009 when the Fermi Gamma-ray Space Telescope detected bursts of gamma-rays from this object. Follow-up observations four days later with the Rossi X-Ray Timing Explorer (RXTE) showed that, in addition to sporadic X-ray bursts, the neutron star exhibits persistent X-ray emission with regular pulsations that indicate that the star has a rotational period of 9.1 seconds.

RXTE was able to monitor this activity for about 100 days. This behaviour is similar to a class of neutron stars called magnetars, which have strong to extreme magnetic fields 20 to 1000 times above the average of the galactic radio pulsars.

As neutron stars rotate, the radiation of low frequency electromagnetic waves or winds of high-energy particles carry energy away from the star, causing the rotation rate of the star to gradually decrease. Careful monitoring of SGR 0418 was possible because

Chandra and XMM-Newton were able to measure its pulsation period even though it faded by a factor of 10 after the initial detection. What sets SGR 0418 apart from other magnetars is that careful monitoring over a span of 490 days has revealed no detectable decrease in its rotation rate.

The lack of rotational slowing implies that the radiation of low frequency waves must be weak, and hence the surface magnetic field must be much weaker than normal. But this raises another question: where does the energy come from to power bursts and the persistent X-ray emission from the source?

The generally accepted answer for magnetars is that the energy to power the X- and gamma-ray emission comes from an internal magnetic field that has been twisted and amplified in the turbulent interior of the neutron star, as depicted in the illustration above.

Theoretical studies indicate that if the internal field becomes about ten or more times stronger than the surface field, the decay or untwisting of the field can lead to the production of steady and bursting X-ray emission through the heating of the neutron star crust or the acceleration of particles.

ESA XMM Newton and NASA Chandra: Large chunk of missing universe found

Large chunk of missing universe found COSMOS magazine


Scientists using two X-ray telescopes have found evidence for the 'missing matter' in the nearby universe.

This matter is made up of hot diffuse gas, which is known as WHIM (warm-hot intergalactic medium).

To get this result, researchers analyzed X-ray light from a distant quasar that passed through a 'wall' of galaxies about 400 million light-years away.

A large chunk of missing matter - theorised but never before measured - has been discovered as a vast smear of extremely hot intergalactic gas 400 million light-years away.


For the predominant theories about the formation and evolution of the universe to hold true, a certain amount of matter should be present; but large amounts of it have long remained elusive.

Now an international team of astronomers have found most of the missing matter, pinpointing its location using two different X-ray telescopes.

Clues to how galaxies formed
"We didn't just find a 'lost & found' item in the cosmic baryon budget," said Taotao Fang of the University of California at Irvine and lead author of the paper in The Astrophysical Journal, "our findings provide important clues to the question of how galaxies formed and evolved.

"The missing matter we found are the leftovers from the early galaxy formation process," said Fang.

The missing matter has long been hypothesised, and some of it has even been spotted before; but previous observations did not uncover the full extent of this massive gas cloud.
Higher temperatures
"What [previous studies] found is the missing matter at lower temperatures ... about 10-20% of the total missing matter," said Fang. "What we found are missing matter at higher temperatures and account for the majority 80 to 90% of the missing matter."
By using two X-ray telescopes, instead of one visible light telescope as in previous studies, the exact location of the missing matter could be calculated and the results were more robust.
The X-ray telescopes that captured the images identifying the location of the missing matter are housed on NASA's Chandra and the European Space Agency's XMM-Newton - which has a command centre in Perth, Australia. Both orbital observatories that have been in space since 1999.