Monday 14 January 2019 — ASTROPHOTOGRAPHY
This is probably the most spectacular nebula (cloud of gas and dust) in the night sky, but is too far south to be visible from the UK. Like the great Orion nebula (visible from here in the winter), this is easily visible with the naked eye, and glorious in any telescope.
The Great Carina Nebula is a complex area of glowing gas and dark dust aprroximately 8,000 light years away from us in the direction of the constellation Carina. Visibly, it’s about four times larger than the famous Orion nebula, but much less well known because of its southern position in the sky. It’s about 230 light years across (compared with the 12 light years of the Orion nebula) and is in a particularly rich part of the Milky Way (hence all the foreground stars in the image). it is one of the concentrations of gas and dust from which stars are being formed in our galaxy. Click on the image below to see it is full size—you may have to zoom in your browser.
Eta Carina is the bright star near the centre of the image (see below). It is remarkable in itself. Observers have seen it change markedly in brightness over time and high magnification shows two lobes of gas around the star. Seeing anything at all of a stellar structure at this distance is extraordinary and speaks of violent and profound events there. It is thought that there are two very energetic stars, very close together, stripping material from each other and igniting, from time to time, into a “nova.” Eta Carina has been one of the brightest stars in the sky in the past and is currently increasing again in brightness (though slowly). About two hundred years ago astronomers saw a major outburst (Nova Carina) and some speculate that another outburst may be due. The Hubble Space telescope shows this “homonculus” lobed nebula around the star very well.
Given the violent events at this star system, and the sort-lived energetic stars that make it up, there is speculation that Eta Carina could “go nova” even more powerfully and destroy itself. It’s impossible to guess when this might be: anything from in the next few years to many thousands of years from now.
Historic accounts of the nebula do not reflect its visual impact on the eye or the telescope. Some, (for example, Stephen James O’Meara in his book: “Deep-Sky Companions—The Caldwell Objects”) wonder if the nebula itself has also varied in brightness as we know the star has, and might be brighter now than when first seen by Westerners.
In any case, this is one of the treasures of the sky and well worth my attempt to photograph it.
I made this image with telescope 12 of iTelescope. This is a 106mm f5 refractor sited in Siding Springs Australia and fitted with a large sensor specialist camera. The colour image was made from 4 two-minute exposures through luminance (plain), red, green and blue filters. I processed it in PixInsight software integrating the separate images with a “drizzle” algorithm which helps to bring out fine detail and also makes a much larger image. You will probably need to zoom if you click through to the full-size image above, which is over 8,000 pixels wide