A Ghost for Halloween

The Ghost Nebula in Cassiopeia makes a perfect object for Halloween season imaging. It is high in the sky and is a fairly easy imaging target. The nebula is being bombarded by radiation from nearby Gamma Cassiopeiae, the bright star at the center of the constellation's distinctive "W." This stellar wind is resposible for the fantail shape of the nebula, which looks like a "ghost sheet."

The object is in a heavily starred region, so I've included starless and starred images. for one of the starred images, I tried to reduce the number of stars by using the "scratches and dust" noise reduction option in Affinity. It does reduce the number of stars, but it also significantly reduces the quality of the image.

Happy Halloween, all!

NGC 7822

 NGC 7822 is a star-forming region in the constellation of Cepheus. The dusty streams and pillars in the nebula are carved out by the young, energetic stars in the nebula. While the nebula is currently a site of starbirth, the radiation from the new stars is destroying the gas and dust necessary for star birth.

I imaged this NGC 7822 this evening, but 24 minutes into the imaging session, clouds rolled in. I decidede to process the captured frames, and the results are surprisingly decent. 

Tech card: RASA 8; DS10C; NBZ filter. 33 x 45 seconds integrations.

     NGC 7822

                          NGC 7822 Crop

     NGC 7822 Starless

The Elephant's Trunk

Nestled in the heart of the extensive emission nebula IC 1396, is the Elephant’s Trunk Nebula—IC 1396A. Images of the Elephant’s Trunk show a dark, elongated cloud illuminated at the edges. This glow is being energized by the massive star, HD 2062067. While many of the stars in this region are very young (c. 100,000 years old), stellar winds from two somewhat older stars in the tip of the Trunk appear to have cleared out the cavity in which they sit. The Trunk itself is around 20 light years long.

My first image of the Elephant’s Trunk was taken years ago with my 14 inch ACF, a DSm camera, and an H II filter. I could just make out the faint outline of the trunk against the image background. The imaging advances in the last few years have been astonishing, and highly sensitive CMOS imagers make IC 1396A a much more accessible object.

IC 1396 is a region of subtle contrasts and colors. In my opinion, many images force contrast too high to give the Trunk more of a 3D aspect. Much of the delicate haziness of the nebula is lost. In the images below, I have tried to preserve this subtlety while bringing out the detail in the nebula itself.

Tech Card: RASA 8; DS10C; NBZ filter. Total integration time, 100 minutes (mix of 40- and 50-second integrations). 

    IC 1396A

IC 1396

IC 1396 Starless

Westerhaut 5--The Soul Nebula

While I have had some success in imaging the Heart Nebula, the Soul Nebula (Westerhaut 5) has always been a challenge. It is significantly fainter than the Heart and my previous images have been plagued by noise, gradients, and hazy detail. Imaging conditions were good last night when I started imaging the Soul, but they declined quite quickly into haze and high clouds. I almost abandoned the session but decided to press on.

Westerhaut 5 is a massive, star forming region. The large cavities in the nebula are carved out by the winds from young, massive stars and the concentration of gas and dust caused by these winds is itself a catalyst for further starburst (a process called “triggered star formation”). The posted images show a full frame picture of the nebula, and two cropped frames of dramatic areas of star formation, with large pillars of gas and dust and dark globules. I’ve also included a starless version of the nebula.

Tech Card: RASA 8; DS10C; NBZ filter. 177 x 45 second integrations (132 mins total). Stars removed, nebula optimized, and stars added back).

IC 1805--The Heart Nebula

IC 1805, the Heart Nebula, was discovered by William Herschel in 1787. It is a popular subject imaging for obvious reasons. The contrast between the pinkish-red ionized hydrogen gas and dark dust clouds in this star-forming region, creates real visual drama. The brightest part of the nebula is to the bottom right of the first image. It consists of the Fish Head Nebula (IC 1795) and NGC 896. At the heart of the nebula is the open cluster Melotte 15. This cluster and the Fish Head are the brightest parts of the nebula.

The first image shows the full, captured frame; the second is the heart of Melotte 15; and the third is a starless image showing maximum detail in the nebulosity.

Tech card: These images were processed from a stack of 160 x 45s integrations (total 120 minutes). RASA 8; DS10C; NBZ filter. Stars were removed, the nebula was processed for optimal brightness and color, and finally, stars were added back.

WR 134

 Wolf-Rayet (WR) stars are rare, highly luminous stars (thousands of times brighter than the Sun) with high surface temperatures. Population I WR stars have exhasted their hydrogen and are fusing helium in their cores. A subset of Population I are WNh stars. WNh stars are young, massive stars fusing hydrogen in their cores, but helium and nitrogen exposed at the star surface. A third group is composed of the central stars of planetary nebulae. These are sunlike stars that have ceased fusion leaving the carbon-oxygen core exposed.

WR 134, in the images below, has blown off an oxygen bubble (blue) that can be clearly seen against the backdrop of the reddish ionized hydrogen cloud and dark sky beyond. 400,000 times brighter than the Sun, WR 134 was one the first of this class of stars, discovered by Charles Wolf and Georges Rayet in 1867. They were identified by their unusual spectra of intense emission lines, rather than the more common absorbtion lines.

The first image below was processed by removing the stars, enhancing the nebula, and then adding the stars back. The second image is the starless version, showing subtleties of the nebula, along with a cropped starred and starless version. WR 134 is the second star from the left in the linear grouping of four stars to the right of the cropped image. I've also included the original image for those interested in seeing the difference processing makes.

Tech card: RASA 8, DS10C, NBZ filter. Approx 100 minutes of integration with 60 second subs.

Heart of the Pelican

 Here's a reprocessed image of the Pelican, showing some of the fine detail in the core region. The Pelican Ridge is about 10 light years long. The tortuous shapes in the cloud are sculpted by massive, hot, young stars. This view shows the deep turbulence in the nebula. If you look closely at gthe long tendril (click to enlarge), you can see the bright, twin jets emerging from protostar Harbig-Haro 555.

The Tulip Nebula (Sh2-101)

The Tulip Nebula is an emission nebula, energized by hot, young stars. It was catalogued by Stewart Sharpless in his 1959 nebula catalog. The companion star to the Cygnus X-1 black hole is also close by in the sky and I have included in the images below a monochrome capture showing this star.

A Starless Tulip

The imge below is enhanced to show stars. The position of the companion star to the Cygnus X1 black hole is ringed in blue.

The final image is a wide field image showing the nebula embedded in a wider area of nebulosity in Cygnus.

The Eastern Veil Nebula (NGC 6992)

 When the moon is bright, as it was last night, I focus on imaging the brighter narrowband objects. A few days ago, I imaged the fainter, Western Veil and Pickering's Triangle. Last night, I imaged the Eastern Veil, and managed around 100 minutes of integration with the RASA 8 and DS10C (NBZ filter) before the clouds moved in. 

The Veil is a supernova remnant created by a star if about 20 solar masses some 10,000 years ago. William Herschel discovered the nebula on Sept. 5, 1784 and described it as streams of branching nebulosity. Our modern cameras can tease out the remarkable complexity of this nebula. NGC 6992 is particularly complex and it sometimes called the "Network Nebula."  The captured images show this wonderful complexity, especially the first image, which is a close, starless crop of the original image capture.

The Heart of Pacman

 

I’ve said before that I believe we are in the Golden Age of amateur astro imaging. I see wonderful images every day taken from backyard telescope that would have been impossible with large, observatory class telescopes not that long ago. For a relatively modest investment, we can buy superb optics, wonderful imagers, and mounts that guide with sub-arcsecond resolution. Amazing when you think about it!

Last night, I took an image of the Pacman Nebula with the RASA 8 and DS10C with just over 2 hours of integration time (30 second subs). The cropped “heart of Pacman” shows why its great to be an imager today. The DS10C supported a huge crop, and still preserved lots of detail. The excellence of the optics of the RASA 8—a mass produced scope, are also evident (to say nothing of the free software bundles that make all this possible, too).

The original image captured and stacked:

New Workflow for Starless Processing of Nebulas

This post is to document the effects of a new workflow using Affinity Photo. This workflow removes the stars from the original image, optimizes processing on the nebula, and then adds the stars back in to the starless image. The result is an image that shows much more nebular detail and preserves the stars.

Original, starred image:

Starless image

Blended Image

The Cygnus Star Cloud

 The Cygnus Star Cloud (Sh2-101) is a rich area of star formation. This image shows the cluster NGC 6871 as well as the Tulip Nebula. I've also included a starless image of the gas and dust that looks a little like an oil painting.

Tech card: 98 minutes total integration time (40s subs); RASA 8; DS10C; NBZ filter.

The Western Veil Nebula

 The Western Veil Nebula (aka the Witch's Broom Nebula, NGC 6960 and Sharpless 103) is a beautiful supernova remnant  Born around 10,000 years ago, this delicate web of gas shows shell-like structures as it expands into the interstellar medium. Note the subtle difference in the distribution of stars above the upper part of the nebula (the Witch's Broom itself) and below it. Above the nebula, invisible dust is obscuring stars, below it, the shock wave of the supernova has cleared it away. The bright star in the image (52 Cygni) is a foreground object and is not associated with the nebula.

Below NGC 6960 is the much fainter Pickering's Triangle. It was discovered in 1904 by Williamina Fleming, but the credit for the discovery went to the director of the observatory, Edward Charles Pickering (which was customary at that time). 

I've included a starless version of the image, which shows in great detail the complexity and delicacy of this wonderful region.

Tech card: RASA 8; DS10C; NBX filter. 2+ hours of integration (individual frames from 24-40 seconds).