Galaxies in gridlock

1 ANSWERS

1. Saba
   

   Nothing draws a crowd like a spectacular crash - whether it's a NASCAR auto race or a galactic collision. Over the past month, Internet users voted for a cosmic smash-up as their favorite target for a future close-up from the Hubble Space Telescope, and this week you can feast your eyes on two fantastic images of galaxies in gridlock.
   
   The first "train wreck" comes from NASA's Spitzer Space Telescope. This is a biggie: Two huge galaxies, each anchored by a central black hole that's millions of times as massive as the sun, are moving toward an imminent pile-up. Exactly how imminent? Millions of years after the scene captured in this image - a time span that's a mereblink of the eye on the cosmic scale.
   
   "One of the most exciting things about the image is that this object is unique," Stephanie Bush of the Harvard-Smithsonian Center for Astrophysics, says in a news release about the observations. "Merging is a quick process, especially when you get to the train wreck that is happening. There just aren't many galactic mergers at this stage in the nearby universe."
   
   Spitzer's image of NGC 6240, which is 400 million light-years away in the constellation Ophiuchus, highlights the bursts of infrared radiation as the dust and gas from the two galaxies slam together. All that pressure creates new generations of hot stars, blazing away in infrared wavelengths even though the radiation in visible wavelengths is obscured by dust clouds. Because of this phenomenon, these starry swirls are known as luminous infrared galaxies.
   
   In the news release, the Spitzer science team point to the streams of stars being ripped off the galaxies - "tidal tails" that extend into space in all directions. And this is just the warmup act: Bush and her colleagues expect the galactic black holes to hit head-on. That would upgrade NGC 6240's status to that of an ultra-luminous infrared galaxy, thousands of times as bright in infrared as our own Milky Way.
   
   The findings are detailed in The Astrophysical Journal. In addition to Bush, the paper's co-authors include Zhong Wang, Margarita Karovska and Giovanni Fazio, all of the Harvard-Smithsonian Center for Astrophysics.
   
   This week's other galactic crash was witnessed by the European Southern Observatory's Very Large Telescope in Chile. Two galaxies are piling into each other 70 million light-years away in the constellation Libra, and just as in the case of NGC 6240, the clashing clouds of gas and dust are sparking waves of stellar fireworks.
   
   
   These galaxies, collectively known as Arp 261, aren't as big as the monsters in NGC 6240. They're on the scale of dwarf galaxies, similar to the Magellanic Clouds orbiting the Milky Way. In this week's image advisory, the ESO says the focus of research in this picture actually isn't the wide-screen view of smashing galaxies, but a detailed look at an unusually long-lasting, X-ray-emitting supernova. This image adds little white bars to highlight the location of the supernova.
   
   The picture also includes other objects at a wide range of distances. If you click on a higher-resolution view, you'll be able to make out a sprinkling of background galaxies on the right side of the picture. Those galaxies may be 50 to 100 times farther away than Arp 261, the ESO says.

   Report (0) (0)  |   12 years, 10 month(s) ago