Friday, February 23, 2007

String of Cosmic Pearls

A String of 'Cosmic Pearls' Surrounds an Exploding Star

On Feb 23 1987 astronomers witnessed one of the brightest stellar explosions in more than 400 years. The titanic supernova, called SN 1987A, blazed with the power of 100 million suns for several months following its discovery. Observations of SN 1987A, made since by NASA’s Hubble Space Telescope and many other major ground- and space-based telescopes, have significantly changed astronomers' views of how massive stars end their lives. Astronomers credit Hubble's sharp vision with yielding important clues about the massive star's demise.

This Hubble telescope image shows the supernova’s triple-ring system, including the bright spots along the inner ring of gas surrounding the exploded star. A shock wave of material unleashed by the stellar blast is slamming into regions along the inner ring, heating them up, and causing them to glow. The ring, about a light-year across, was probably shed by the star about 20,000 years before it exploded

Full story ... from Hubblesite releases

XMM-Newton view of supernova SN 1987A

XMM-Newton’s anniversary view of supernova SN 1987A
Twenty years after the first detection of SN 1987A, the nearest supernova ever detected since the invention of the telescope, XMM-Newton provided a fresh-new view of this object. The source keeps brightening - XMM-Newton confirms.

SN 1987A provides the unique opportunity for detailed studies of the earliest stages of a supernova remnant. Observations across the whole electromagnetic spectrum revealed a detailed picture of the circumstellar medium produced by the stellar wind from the massive pregenitor star during its 'supergiant' phases.

The X-rays we see mainly originate from the interaction of the supernova shock with this circumstellar medium. Their detailed analysis will gain further insights into the physics of the explosion and may reveal eventually the presence of a central compact object like a neutron star.

More on Supernova 1987a - by Stefan @ Backreaction
The Theory of Evolution of Supernovae from Dialogues of Eide
Taurus-Auriga: XMM-Newton reveals a magnetic surprise

As part of a large programme to survey Taurus-Auriga at X-ray wavelengths, XMM-Newton systematically targeted AB Aurigae and the other young stars in this region, using its European Photon Imaging Camera (EPIC). AB Aurigae stood out brightly in the image, indicating that it was releasing X-rays.

At 2.7 times the mass of the Sun, AB Aurigae is one of the most massive stars in the Taurus-Auriga star-forming cloud. Although amongst nearly 400 smaller stars, its ultraviolet radiation plays a key role in shaping the cloud. Its massive status puts it in a class known as Herbig stars, named after their discoverer George Herbig.

X-rays are expected to come from young stars with strong magnetic fields but computer calculations have repeatedly suggested that Herbig stars do not have the correct internal conditions to generate an appreciable magnetic field. Yet for twenty years, astronomers have been detecting X-ray emission from them.

Full story ... XMM-Newton reveals a magnetic surprise
Map of TAURUS, AURIGA (Chariot), GEMINI, ORION & The Pleiades by uiuc
Cosmic Lighthouses: Astrophysicists from the Max Planck Institute
Explain Differences In Brightness Of Supernova Explosions

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