When I integrated the first lot of data for this magnificent galaxy, I found what appeared to be straight lines apparently emanating from the galaxy core. One of them has a right angle piece at one end. I immediately assumed they were an arefact like reflections etc. But then I found them in the images of others!! I had 20-25 LRGB images of 10 mins apiece and 14 half hour Ha images. The star streams are quite tenuous, so I decided I would need a lot more data to bring them out. It made sense to gather extra Luminance data. In the end I captured 63 useable Luminance images, to give a very high Signal to Noise Ratio. I was onto this one early in its apparition, so I had high hopes of getting a lot of data to supplement the initial tranche. But four cloudy/ rainy new Moons in a row greatly limited what I could get. Nevertheless, the extra hours of data I did manage to secure made a big difference to the prominence of the star streams.

But what are these emanations? Apprently they are star streams. The mouse over shows the starless image (Revision B) produced by StarXTerminator in PixInsight and here the star streams can be seen much more clearly, without inteference from the stars. However, these are best seen on a full screen in a darkened room.

The following extract from Wikipedia outlines the current state of knowedge:

“NGC 1097 (also known as Caldwell 67) is a barred spiral galaxy about 45 million light years away in the constellation Fornax. It was discovered by William Herschel on 9 October 1790. It is a strongly interacting galaxy with obvious tidal debris and distortions caused by interaction with the companion galaxy NGC 1097A.NGC 1097 is also a Seyfert galaxy. Deep photographs revealed four narrow optical jets that appear to emanate from the nucleus. These have been interpreted as manifestations of the (currently weak) active nucleus. Subsequent analysis of the brightest jet's radio-to-X-ray spectral energy distribution were able to rule out synchrotron and thermal free-free emission. The optical jets are in fact composed of stars. The failure to detect atomic hydrogen gas in the jets (under the assumption that they were an example of tidal tails) using deep 21 cm HI imaging with the Very Large Array radio telescope and numerical simulations led to the current interpretation that the jets are actually the shattered remains of a cannibalized dwarf galaxy. NGC 1097 has a supermassive black hole at its centre, which is 140 million times the mass of the Sun. Around the central black hole is a glowing ring of star-forming regions with a network of gas and dust that spirals from the ring to the black hole. An inflow of material toward the central bar of the galaxy causes new stars to be created in the ring. The ring is approximately 5,000 light-years in diameter, the spiral arms of the galaxy extend tens of thousands of light-years beyond the ring. NGC 1097 has two satellite galaxies, NGC 1097A and NGC 1097B. Dwarf elliptical galaxy NGC 1097A is the larger of the two. It is a peculiar elliptical galaxy that orbits 42,000 light-years from the centre of NGC 1097. Dwarf galaxy NGC 1097B (5 x 106 solar masses), the outermost one, was discovered by its HI emission and appears to be a typical dwarf irregular. Little else is known about it.” …. Wikipedia (abridged)

I was pleased with the lovely detail seen in the inner galaxy ring. It is quite bright in Ha and I had to subdue that to avoid the ring having an unnatural pink hue. The final image shows this nicely with an ever so slight pink tinge, but mostly the white colour seen in professionally derived images. Meanwhile the pink knots of Ha in the spiral arms came through well. At 45 light years, this is near the limit of distance where my Ha filter (656nm +/- 3nm) can capture the Ha. Beyond about 60 million light years, red shift moves the emission line out of my filter window.

The linearity of the star streams is hard to understand, especially all four of them. The one that extends fom centre to upper left is perhaps better seen in this image than any other I was able to find. The right angled part at lower right is most likely a separate star stream, again linear in nature and in a different plane to the perpendicualr one it traverses.

One of the most fascinating galaxies I have imaged.