Jekyll2026-07-13T20:33:44+00:00https://chryse.co.uk/feed.xmlAmong StarsAstrophotography from Edinburgh, Scotland — deep-sky notes on galaxies, nebulae, clusters and comets captured with a Dwarf 3 smart telescope.Sadr’s Butterfly: A Trick of Perspective2026-07-13T00:00:00+00:002026-07-13T00:00:00+00:00https://chryse.co.uk/blog/2026/07/13/gamma-cygni-nebula72 minutes on Cygnus tonight, aimed at the bright star Sadr and the huge field of nebulosity that surrounds it — IC 1318, usually called the Gamma Cygni Nebula after Sadr’s other name, or the Butterfly Nebula for the wing-like lobes that spread out on either side of the star.

It’s a bit of a trick of perspective. Sadr looks like it’s sitting right in the middle of the glow, but the star and the nebula aren’t actually related at all — they just happen to line up from Earth’s point of view. Sadr is a relatively nearby supergiant, about 1,800 light-years out. The nebula behind it is roughly three times farther, at somewhere around 4,900 light-years, and Sadr isn’t even bright enough in the right part of the spectrum to be lighting it up. That job belongs to a hot O9-class star buried somewhere deeper in the dust, energetic enough to ionise hydrogen across hundreds of light-years but too obscured to actually see.

What that leaves is one of the largest emission nebula complexes visible from Earth, and one of the faintest — huge in apparent size but low in surface brightness, which is exactly why it rewards longer integration rather than a quick grab. Even at just over an hour, the wings either side of Sadr start to separate out from the surrounding star field, hydrogen-alpha structure threading through in loops and filaments that don’t show up at all to the eye.

Worth coming back to with more integration time at some point — this is very much a first pass. Full details and the 3D distance view are on the gallery card.

]]>Chasing the Bubble Nebula2026-07-10T00:00:00+00:002026-07-10T00:00:00+00:00https://chryse.co.uk/blog/2026/07/10/bubble-nebulaCassiopeia was the target this session, and specifically the object that gives this nebula its name: a shell of gas nearly seven light-years across, blown outward by a single furious star. NGC 7635 — Caldwell 11 to backyard observers, Sharpless 162 in the catalogues — sits around 7,100 light-years away, close enough for the Dwarf 3 to start resolving real structure in just over two hours of integration from here in Edinburgh.

The bubble itself is the work of SAO 20575, a star roughly 45 times the mass of the Sun, driving a stellar wind so powerful it has hollowed out a near-perfect sphere in the surrounding gas. Look closely, though, and the star isn’t centred in its own creation — it sits noticeably off to one side. The molecular cloud around it is denser on that side, so the shell has been pushing harder and faster into the thinner gas on the other, giving the whole structure a lopsided, almost breathing quality rather than a clean circle.

That same cloud is doing double duty: it confines the bubble, and it glows. SAO 20575 is pouring out ultraviolet radiation, and where it hits the surrounding gas it lights up in the red and blue hues that make this one of the more striking emission nebulae in the northern sky.

It won’t last. A star this massive burns through its fuel fast, and the current thinking is SAO 20575 has somewhere between ten and twenty million years left before it goes supernova — an eyeblink, astronomically speaking. When it does, the explosion will tear through the very bubble the star spent its life inflating. What we’re looking at tonight is a structure actively building toward its own destruction, just on a timescale too slow for any of us to watch it happen.

Worth the 2h 11m. Full details and the 3D distance view are on the gallery card.

]]>