Tuesday, 29 August 2017

NGC6818: a Little Gem

When visiting Barnard's Galaxy, don't forget to turn slightly to the north because there you'll find a little surprise. NGC6818's popularly known as the "Little Gem Nebula" and with good reason too. It's a small but very bright planetary nebula which will reveal a lot of detail also in smaller telescopes. With my 18" binoscope at 507x the main outer halo was obvious and within I could see a large numbers of clouds that are currently being blown away by the dying central star. This central star was invisible to me, unfortunately enough, because it's not an ordinary star. In fact, it's a system of two stars, separated by 5 times the distance between our Sun and Neptune. Given that the Little Gem lies a whopping 6,000 light-years away, it would be impossible to separate those stars with an amateur telescope anyway because they're too close to one another. Yet, the effect of the binary system on the planetary nebula is more than obvious because the expelled gas clouds are severely distorted, if you compare them for instance with the Saturn Nebula. The nebula's also fairly young, no more than 3,500 years old, and has reached a size of about half a light-year.

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