Tuesday, 30 August 2016

The tadpole galaxy

Often you could accuse astronomers of being overly fanciful when they invent nicknames for the things they've discovered or the constellations they've assigned. You might even believe that the astronomy society's a less successful branch of alcoholics anonymous. :-) But at times you don't need a lot of fantasy to understand why a certain object was given a certain name. Such is the case with the distant galaxy that's the protagonist of this sketch.

I've taken my new binoscope for a five nights' holiday in the Dolomites, at an elevation of 2000 metres and under a sky of a rare darkness. The goal: hunt the faintest fuzzies! The "tadpole galaxy"(or scientifically UGC10214 or Arp188) is quite faint indeed, being of magnitude 14,4, but it's one of the most spectacular of them all. Most galaxies are round or elliptical but this one has an unusual straight tail that's 280.000 lightyears long. Scientists believe that a smaller and more compact galaxy's come too close and that their mutual gravitational forces slung it around the "tadpole". Gas, dust and millions of stars were torn out of the larger one and formed the striking tail. Over time, the "tadpole" will lose its tail, which will probably contract into dwarf galaxies that accompany their mother. The intruder's not visible on the sketch because it now lies somewhere behind the "tadpole", but it can be seen on high-resolution photos of the Hubble space telescope. My binoscope's quite powerful but certainly not that powerful. Bear in mind that this particular galaxy lies at a distance of a whopping 460 million lightyears and therefore it must be the most distant object that I've observed thusfar. 

For those with a keen eye... there's a second galaxy on my sketch, smaller and even fainter. Its scientific denominator's PGC57108, it's of magnitude 15,5 and lies at approximately the same distance. I dare you to find it! :-) 

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