NGC 6960, the Witch's Broom (also Western Veil or Sharpless 103) Nebula is a remnant from a supernova about 10,000 years ago. Its amazing filamentary structure is due to compression of expanding shells of gas as they meet the resistance of the interstellar medium. That much of what we see as "empty" space is filled with dark dust is evidenced by there being more background stars visible below the nebula, where it has swept space clear of dust, than above it. The bright star, 52 Cygni, is a type K star and a foreground object with no physical association with the nebula, but adds to the drama of the image. Please compare this image to my previous image of it taken with my Celestron Compustar C14, shown under Nebulae. The difference in sharpness, clarity, and detail is jaw-dropping.
Telescope/Mount: PlaneWave CDK17 on L500 mount
Exposures: Ha:L:R:G:B = 300:245:95:95:95 minutes = 11 hours, 40 minutes total exposure at f/6.8.
M33 is one of the closest spiral galaxies lying at a distance of 2,723,000. It therefore appears large and also presents us with a nearly face-on view. As such, it reads like an open book on all the processes we can see going on in a spiral galaxy. Dark dust clouds condense into hot blue supergiant stars. They emit intense ultraviolet radiation that strike the remaining hydrogen gas in the cloud and cause it to glow red as an emission nebula at the hydrogen-alpha frequency of 656.28 nm. They also emit fierce stellar winds that drive the gas away and the stars within the nebula become unbound and spread out as an OB association of blue supergiants. But those blue supergiants live fast and die young as supernovae within a few million years. The shockwaves from the supernovae compresses gas in neighboring dark clouds, causing them to collapse and the process repeats. As the galaxy rotates over millions of years, these processes trace out curving spiral arms of blue supergiants ornamented with red emission nebulae. Compare this image with my previous image of M33 taken with the Celestron Compustar C14, shown under Galaxies. The difference in sharpness, clarity, and detail is jaw-dropping.
Telescope/Mount: PlaneWave CDK17 on L500 mount.
Exposures: Ha:L:R:G:B = 480:460:110:110:110 minutes = 21 hours, 10 minutes total exposure at f/6.8/
M75 is a globular cluster in Sagittarius lying at a distance of 67,500 light-years. This means when we view M75, we are peering past the south side of the Milky Way galaxy’s core and seeing this globular cluster hovering over the outskirts of the far side of our galaxy’s disk. Harlow Shapley and Helen Sawyer classified globular clusters on a scale of I-XII based on how densely packed they are. Class I globulars are so densely packed as to have unresolvable cores, whereas class XII are so loosely packed as to resemble circular open star clusters. M75 is the only Class I globular in the Messier Catalog and is notorious for being so densely packed as to be unresolvable through even the largest amateur telescopes. However, photographically, the CDK17 resolved the core of this globular cluster spectacularly well.
Telescope/Mount: PlaneWave CDK17 on L500 mount.
Exposures: L:R:G:B = 165:60:60:60 minutes = 5 hours, 40 minutes total exposure at f/6.8.
M79 is a rare wintertime globular cluster in the constellation Lepus, just south of Orion. It is a historically important globular cluster. In 1918, Harlow Shapley calculated the distances to globular clusters and plotted their distribution. They had a spherical distribution around the plane of the Milky Way and there were many in the direction of Sagittarius, some of which he found lay at tremendous distances. However, he found only three in the opposite direction all lying at moderate distances. By correctly assuming that the center of the sphere coincided with the center of the Milky Way, he deduced that we were not at the center of the galaxy, but about half way out toward the edge of the disk, giving us our biggest demotion of position in the universe since Copernicus put the sun at the center of the solar system.
One can see the entire process of new star formation in this view of the iconic Horsehead Nebula in Orion. The blue supergiants star Sigma Orionis, which is above the field of view, is emitting intense ultraviolet radiation that is ionizing the hydrogen in the emission nebula IC 434, causing it to glow red at a wavelength of 656.28 nm. That star is also emitting fierce stellar winds that are creating wisps and streaks within the nebula and also cause it to pile up as a shock wave as it encounters the resistance of the large dark molecular dust cloud, Lynds Dark Nebula 1630. However, there are some persistent intrusions of the dark nebula into the emission nebula, such as the Horsehead Nebula itself. As the fierces stellar winds continue to apply pressure to the edges of these intrusions, the hydrogen within them becomes compressed and eventually gravity takes over and the hydrogen collapses into a newborn star.
The newborn star will emit its own fierce stellar winds that will drive away the surounding dust and star will emerge from the dark nebula. Because the surrounding dust scatters the light from the star, the surrounding area appears blue, just as Earth’s atmosphere scatters light from the Sun makes the sky appear blue, creating a blue reflection nebula. These processes are visible in the blue reflection nebula NGC 2023 at the bottom left of the image.
Telescope/Mount: PlaneWave CDK17 on L500 mount.
Camera: SBIB STL 11000M with Baader Planetarium Ha, L, R, G, and B filters.
Exposures: Ha:L:R:G:B = 1155:175:85:85:85 minutes = 26 hours, 25 minutes total exposure.
One can see the entire process of new star formation in this view of the iconic Horsehead Nebula in Orion. The blue supergiants star Sigma Orionis, which is above the field of view, is emitting intense ultraviolet radiation that is ionizing the hydrogen in the emission nebula IC 434, causing it to glow red at a wavelength of 656.28 nm. That star is also emitting fierce stellar winds that are creating wisps and streaks within the nebula and also cause it to pile up as a shock wave as it encounters the resistance of the large dark molecular dust cloud, Lynds Dark Nebula 1630. However, there are some persistent intrusions of the dark nebula into the emission nebula, such as the Horsehead Nebula itself. As the fierces stellar winds continue to apply pressure to the edges of these intrusions, the hydrogen within them becomes compressed and eventually gravity takes over and the hydrogen collapses into a newborn star.
The newborn star will emit its own fierce stellar winds that will drive away the surounding dust and star will emerge from the dark nebula. Because the surrounding dust scatters the light from the star, the surrounding area appears blue, just as Earth’s atmosphere scatters light from the Sun makes the sky appear blue, creating a blue reflection nebula. These processes are visible in the blue reflection nebula NGC 2023 at the bottom left of the image.
This image was shot completely unguided with a total exposure of over 26 hours, which is a testament to the superb tracking accuracy of the L500 mount.
Telescope/Mount: PlaneWave CDK17 on L500 mount.
Camera: SBIB STL 11000M with Baader Planetarium Ha, L, R, G, and B filters.
Exposures: Ha:L:R:G:B = 1155:175:85:85:85 minutes = 26 hours, 25 minutes total exposure.
Sh2-96, also known as LBN066 is an extremely faint emission nebula in Cygnus and rarely imaged. It is known as the Scarlet Letter Nebula, and just like in the novel The Scarlet Letter by Nathaniel Hawthorne, the letter outlined by this nebula is a capital A. The field also abounds with faint hydrogen-alpha nebulosity. The image required more than 21 hours of total exposure time.
Instrument/mount: PlaneWave CDK17 on L-500 mount.
Camera: SBIG STL11000M with Baader Planterium Ha, L, R, G, and B filters, guided.
Messier 78 is a blue reflection nebula in Orion. It is located just a bit northeast of the stars in Orion’s belt and lies 1,350 light-years from Earth. M78 is the brightest reflection nebula in the sky and its blue color results from the scattering of light emitted from the bright stars in the nebula, just as how our atmosphere’s scattering of sunlight results in a blue sky. M78 is in the center of the image while blue reflection nebula NGC 2064 is peering out from behind dust above it, NGC 2067 is to its upper left, and NGC 2071 is in the lower left corner. The dark nebulae are part of molecular cloud L1630 in Orion. This region of the sky is rich in Herbig-Haro (HH) objects, newborn stars with bipolar outflows that strike the dark dust and cause it to glow red. HH 24 and HH25 mark the locations of stars just emerging from the dark nebula in the upper right corner. Just above the double star in the upper right is the location of McNeil’s variable nebula. It became invisible in November, 2018 and hasn’t been seen since.
Image Data:
Telescope/mount: CDK17 on L500 mount
Camera: SBIG STL 11000 with Baader Planetarium L,R,G, and B filters.
Exposures: L:R:G:B 235:75:75:75 minutes =7 hours 40 minutes total exposure, all completely unguided.