New images from telescopes on Earth and in space are providing the inside stories behind a galactic smash-up and a stellar blast. These all-over views are not only scientically valuable - they're stunningly beautiful as well. Today's offering from the Chandra X-Ray Observatory Center features the Antennae galaxies, which are in the midst of a merger 62 million light-years from Earth in the constellation Corvus. The Antennae, named after the long whiplike tails that point out from each galaxy like rabbit ears, have had many turns in the astronomical spotlight. In fact, Hubble's view of the scene is included in our roundup of classic Hubble hits. The new imagery, however, adds in Chandra's X-ray view in blue as well as the Spitzer Space Telescope's infrared perspective in deep red. The bluest patches highlight clouds of hot, interstellar gas that have been enriched with rich deposits of heavy elements from supernova explosions. Bright points of blue are produced by material falling onto black holes and neutron stars. The central concentration of red is associated with warm clouds of dust that are being heated by the newborn stars within. Those stars are being squeezed into existence due to gravitational pressure from the clashing galaxies. The Hubble imagery, in shades of gold and brown, provide the image's visible-light backbone. When you go to the Chandra website, click on the tabs to see how readings from different wavelengths have been blended together. NASA is fortunate in having three "Great Observatories" that can triple-team complex objects such as the Antennae. In this case, the results shed light (so to speak) on the violent processes that lead to starbirth as well as galactic mergers and acquisitions. Our own Milky Way galaxy is heading toward just such a merger with the Andromeda galaxy ... a few billion years from now. Now let's turn from the birth of stars to their death: Astronomers at the European Southern Observatory have reconstructed the 3-D structure and movement at the core of a supernova remnant known as SN 1987A, in order to figure out how the asymmetric explosion took shape. The stellar blast, which was observed in 1987, occurred about 187,000 light-years away in the constellation Dorado, within the Large Magellanic Cloud. Over the years, astronomers have been tracing how leftovers from the blast spread out and interacted with the surrounding interstellar medium. The new observations, made using the SINFONI spectrograph on the ESO's Very Large Telescope in Chile, reveal that the explosion was stronger and faster in some directions than others. That explains why SN 1987A has such an unusual shape today. SINFONI was well-suited for the job because it can measure the velocity as well as the composition Here's how the ESO team put it in Wednesday's image advisory: "The first material to be ejected from the explosion traveled at an incredible 100 million kilometers per hour, which is about a tenth of the speed of light or around 100,000 times faster than a passenger jet. Even at this breakneck speed it has taken 10 years to reach a previously existing ring of gas and dust puffed out from the dying star. The images also demonstrate that another wave of material is traveling 10 times more slowly and is being heated by radioactive elements created in the explosion. "'We have established the velocity distribution of the inner ejecta of Supernova 1987A,' says lead author Karina Kjær. 'Just how a supernova explodes is not very well understood, but the way the star exploded is imprinted on this inner material. We can see that this material was not ejected symmetrically in all directions, but rather seems to have had a preferred direction. Besides, this direction is different to what was expected from the position of the ring.' "Such asymmetric behavior was predicted by some of the most recent computer models of supernovae, which found that large-scale instabilities take place during the explosion. The new observations are thus the first direct confirmation of such models." The research paper, titled "The 3-D Structure of SN 1987A's Inner Ejecta," is to appear in the journal Astronomy and Astrophysics. In addition to Kjær, an astronomer at Queen's University Belfast, authors of the paper include Bruno Leibundgut and Jason Spyromilio of the ESO and Claes Fransson and Anders Jerkstrand of Stockholm University.
NASA / GSFC / ASU An annotated image of Gruithuisen K, captured by NASA's Lunar Reconnaissance Orbiter, highlights the concentric crater's inner and outer rims.
Finally, here's a kicker to the "Martian bull's-eye" picture I wrote about on Wednesday. It just so happened that the team behind the Lunar Reconnaissance Orbiter Camera featured a similar picture on the same day ... but from the moon, not Mars. The concentric crater Gruithuisen K was probably created when a cosmic object slammed into a stretch of terrain with layers of harder and softer material. The result could have been a crater with multiple rims - just like Gruithuisen K. The look of the lunar bull's-eye leaves me inclined to think that the bull's-eye on Mars had a similar genesis, due to layered terrain rather than a lucky double strike. But what do you think? Here's your chance to point to other odd-looking pictures from the moon, Mars or beyond. Join the Cosmic Log corps by signing up as my Facebook friend or hooking up on Twitter. And if you really want to be friendly, ask me about "The Case for Pluto."