ESA XMM-Newton: Cosmic Ornament

Image Credit: NASA/CXC/Univ. of Potsdam/L. Oskinova et al.

A new image from an assembly of telescopes reveals a pulsar that appears like a spinning cosmic ornament. Combined data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton were used in the discovery of a young pulsar in the remains of a supernova located in the Small Magellanic Cloud, or SMC.

This is the first time a pulsar, which is a spinning, ultra-dense star, has been found in a supernova remnant in the SMC, a small satellite galaxy to the Milky Way.

In this composite image, X-rays from Chandra and XMM-Newton have been colored blue and optical data from the Cerro Tololo Inter-American Observatory in Chile are coloured red and green.

The pulsar, known as SXP 1062, is the bright white source located on the right-hand side of the image in the middle of the diffuse blue emission inside a red shell.

The diffuse X-rays and optical shell are both evidence of a supernova remnant surrounding the pulsar. The optical data also displays spectacular formations of gas and dust in a star-forming region on the left side of the image.

SXP 1062 interests astronomers because the Chandra and XMM-Newton data show that it is rotating unusually slowly -- about once every 18 minutes. (In contrast, some pulsars are found to revolve multiple times per second, including most newly born pulsars.)

This relatively leisurely pace of SXP 1062 makes it one of the slowest rotating X-ray pulsars in the SMC.

Scientists have estimated that the supernova remnant around SXP 1062 is between 10,000 and 40,000 years old, as it appears in the image.

This means that the pulsar is very young, from an astronomical perspective, since it was presumably formed in the same explosion that produced the supernova remnant.

Therefore, assuming that it was born with rapid spin, it is a mystery why SXP 1062 has been able to slow down by so much, so quickly.

Work has already begun on theoretical models to understand the evolution of this unusual object.

Has Graphene Been Detected in Space?

Artist's impression of the graphenes (C24) and fullerenes found in a planetary nebula. 

The detection of graphenes and fullerenes around old stars as common as our Sun suggests that these molecules and other allotropic forms of carbon may be widespread in space. 

Credit: IAC; original image of the Helix Nebula: NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner, STScI and T.A. Rector, NRAO.

A team of astronomers, using the Spitzer Space Telescope, have reported the first extragalactic detection of the C70 fullerene molecule, and the possible detection of planar C24 ("a piece of graphene") in space.

Letizia Stanghellini and Richard Shaw, members of the team at the National Optical Astronomy Observatory in Tucson, Arizona, describe how collisional shocks powered by the winds from old stars in planetary nebulae could be responsible for the formation of fullerenes (C60 and C70) and graphene (planar C24).

The team is led by Domingo Anibal Garcia-Hernandez of the Instituto de Astrofisica de Canarias in Spain and includes international astronomers and biochemists.

Planetary nebulae originate from stars similar to our Sun that have reached the end of their lives and are shedding shells of gas into space. In this case, the planetary nebulae are located in the Magellanic Clouds, two satellite galaxies to our own Milky Way, that are best seen from the Southern Hemisphere. At the distance of the Magellanic Clouds, planetary nebulae appear as small fuzzy blobs.

However, unlike planetaries in our own Milky Way Galaxy whose distances are very uncertain, the distance to planetaries in the Magellanic Clouds can be determined to better than 5%. With such accurate distances, the research team determined the true luminosity of the stars and confirmed that the objects are indeed planetary nebulae and not some other object in the astrophysical zoo.

Fullerenes, or Buckyballs, are known from laboratory work on Earth and have many interesting and important properties. Fullerenes consist of carbon atoms arranged in a three dimensional sphere similar to the geodesic domes popularized by Buckminster Fuller.

The C70 fullerene can be compared with a rugby ball, while C60 is compared to a soccer ball. Both of these molecules have been detected in the sample. Graphene (planar C24) is a flat sheet of carbon atoms, one atom thick, that has extraordinary strength, conductivity, elasticity and thinness.

Cited as the thinnest substance known, graphene was first synthesized in the lab in 2004 by Geim and Novoselov for which they received the 2010 Nobel Prize in physics. "If confirmed with laboratory spectroscopy - something that is almost impossible with the present techniques - this would be the first detection of graphene in space," said team member Garcia-Hernandez.

The team has proposed that fullerenes and graphene are formed from the shock-induced (i.e., grain-grain collisions) destruction of hydrogenated amorphous carbon grains (HACs). Such collisions are expected in the stellar winds emanating from planetary nebulae, and this team sees evidence for strong stellar winds in the ultraviolet spectra of these stars.

"What is particularly surprising is that the existence of these molecules does not depend on the stellar temperature, but on the strength of the wind shocks," says Stanghellini.

The Small Magellanic Cloud is particularly poor in metals (any element besides hydrogen and helium, in astronomers' parlance), but this sort of environment favors the evolution of carbon-rich planetary nebulae, which turns out to be a favorable place for complex carbon molecules.

ESA ESO VLTelescope: Nebula LHA 120-N 44

The nebula LHA 120-N 44 surrounding the star cluster NGC 1929 is seen in this image taken with ESO’s Very Large Telescope.

Lying within the Large Magellanic Cloud, a satellite galaxy of our own Milky Way, this region of star formation features a colossal superbubble of material expanding outwards due to the influence of the cluster of young stars at its heart that sculpts the interstellar landscape and drives forward the nebula’s evolution.

Picture: ESO/Manu Mejias/EUROPEAN SOUTHERN OBSERVATORY/ AFP

Cosmic spokes and pummelled planets: 1,000 Years Old

The explosion of a massive star more than 1000 years ago created this colourful remnant, called E0102. It sits some 190,000 light years away in a nearby galaxy called the Small Magellanic Cloud.

The ejected remains seem to form a cylinder that we see end-on. The highest-energy X-rays are shown in blue, and the lowest in orange. A star not visible in this image is responsible for illuminating the green cloud of gas and dust on the lower right.

This image is a composite taken by the Hubble Space Telescope and the orbiting Chandra X-ray Observatory, in celebration of the 10th anniversary of Chandra's deployment after launching into space aboard the space shuttle Columbia.

(Image: X-ray: NASA/CXC/MIT/ D. Dewey et al./SAO/J. DePasquale; Optical: NASA/STScI)