interstellar – The Amazing Sky

A run of exceptionally clear nights allowed me to capture scenes of stardust along the MilkyWay.

Colourful nebulas – clouds of glowing gas – are the most popular targets in the deep sky for astrophotographers. Most nebulas emit red light from hydrogen atoms. Some glow blue by reflecting the light of nearby hot stars.

But another class of nebulas emits or reflects almost no light, and appears dark, often as shapes silhouetted against the bright starry background. They are usually made of obscuring interstellar dust – typically grains of carbon soot emitted by aging or active stars – literally stardust.

In the olden days of film photography, these dark dust clouds always appeared black in our exposures. Or they never showed up at all.

But today’s digital cameras, with the aid of processing techniques, can capture the dust clouds, often not as black clouds, but as pale blue tendrils, or as brownish-yellow streamers faintly glowing with a warm light.

In October and November 2023, a series of unusually clear and mild nights allowed me to go after some of these dark and dusty targets, from my home in rural southern Alberta, Canada. I captured a selection of scenes off the beaten track along the Milky Way. Here’s my tour of stardust sights in the northern autumn and winter sky.

Cepheus the King

The wide-field image above frames most of the northern constellation of Cepheus. The southern section of Cepheus at the bottom of the frame lies in the Milky Way and is rich in bright red nebulas, notably the large, round IC 1396. It is a popular and easy target. But the northern upper reaches of Cepheus are where more challenging dusty nebulas reside. I’ve indicated the location of two fields shown in the close-ups below.

The Iris Nebula

Located some 1300 light years away, this is a blue reflection nebula, as the dust is lit by the young blue star in its core. But surrounding the bright Iris Nebula are more extensive clouds of dust, dimly lit by reflected light and with varying densities and shades of grey and brown.

The Dark Shark and Wolf’s Cave Nebulas

This is a portrait of a field of dusty nebulas in northern Cepheus, in a stack of 30 x 6-minute exposures with the Astro-Tech AT90CFT refractor at f/4.8 and filter-modified Canon EOS R camera at ISO 800, though no filter was used when taking these frames.

This field in northern Cepheus is yellowed by reams of dust. A couple of blue reflection nebulas lie on the edges of streamers of brown dust. The object at top is called the Dark Shark, for its fanciful resemblance to a menacing shark, though one wearing a blue hat!

At the bottom of the frame is a long, snake-like dark brown nebula, Barnard 175, with the blue reflection nebula van den Bergh (vdB) 152 at its tip. This object has been dubbed the Wolf’s Cave Nebula, though that likeness is harder to discern. It is unclear where some of these nicknames come from, as many are recent appellations invented by astrophotographers. Some of the names have stuck, though few are “official.”

Perseus the Hero and Taurus the Bull

This is a portrait of the dust-filled region of sky from Perseus down to Taurus that includes the pink California Nebula (NGC 1499) at top down to the Pleiades star cluster (M45) at bottom. This is a stack of 48 x 2-minute exposures with the rare Samyang RF85mm f/1.4 lens stopped down to f/2.8, on the Canon EOS Ra camera at ISO 800. The lens was equipped with a 77mm Nisi Clear Night broadband filter.

The region of sky between Perseus and Taurus is rich in bright nebulas set amid large tendrils of dust in Taurus. The Pleiades star cluster lights up a portion of the dust clouds. And the pink California Nebula lies at the end of a large lane of dust.

The California Nebula

The California Nebula (named for its resemblance to the shape of the state) lies in Perseus. It is a bright emission nebula glowing in the red and pink light of hydrogen atoms, perhaps excited by blue-white Xi Persei, aka Menkib, at bottom. But it sits amid wider clouds of dust, here recorded as white and yellow.

IC 348

This complex mix of reflection and dark nebulas surrounds Omicron Persei. In some sections the dust is so dense it blocks all light from more distant stars. Once thought to be holes in the heavens, the photos of pioneering astrophotographer Edward Emerson Barnard in the early 20th century proved that dark nebulas are nearby, and obscure what’s behind them.

IC 348’s distance of only 700 light years means there isn’t much between us and the surrounding dark clouds. Oddly, though a popular target, as best I can tell, no one has come up with a nickname for this field. What can you see in the dark shapes?

The Pleiades / Messier 45

This frames the famous Pleiades or Seven Sisters star cluster (aka Messier or M45) set amid a dusty starfield in Taurus. The field is about 4.7° by 3.2°. This is a stack of 30 x 6-minute exposures with the Astro-Tech AT90CFT refractor at f/4.8 (using its 0.8x Reducer) and the filter-modified Canon R camera at ISO 800.

There’s no more famous deep-sky object than the blue Pleiades, or Seven Sisters. They feature in the mythology of almost all cultures around the world. The young blue stars are surrounded by bright blue reflection nebulosity, most prominent below the lower star Merope, a bit of nebula catalogued separately as NGC 1435.

While the Pleiades light up the core of the dust clouds blue, the dust clouds extend much wider and permeate the entire constellation of Taurus. However, the outlying clouds are very faint as they have no nearby source of illumination. The arc of nebulosity at top is most obvious. It was found by Barnard and is catalogued as IC 353.

Taurus the Bull

This is a portrait of the dust-filled region of sky in Taurus that frames the Hyades star cluster (at bottom) with bright yellow Aldebaran, up to the blue Pleiades star cluster (M45) at top. This is a stack of 48 x 2-minute exposures with the Samyang RF85mm f/1.4 lens at f/2.8, on the Canon EOS Ra camera at ISO 800.

Overlapping the previous constellation field, this framing extends farther south, continuing past the Pleiades down into the main section of Taurus the Bull, with the luminous yellow star Aldebaran marking the Bull’s eye. It is surrounded by the stars of the V-shaped Hyades star cluster, legendary half-sisters to the Pleiades.

Notable in this framing are the large dark tendrils of the Taurus Molecular Clouds, dense streams of dust only about 430 light years away. They are on my shot list for close-ups on upcoming clear winter nights.

NGC 1555 and Area

This is a framing of dust clouds among the stars of the Hyades star cluster in Taurus. The field of view is 4.7° by 3.2°. This is a stack of 30 x 6-minute exposures with the Astro-Tech AT90CFT refractor at f/4.8 and the filter-modified Canon EOS R camera at ISO 800, though no filter was used in taking the images.

This complex field lies on the northern edge of the Hyades. At upper right is the odd nebula NGC 1555, discovered by John Russell Hind in 1852 and variable in brightness due to changes in its embedded source star T Tauri, a prototype of a class of young, newly formed stars. An adjacent object, NGC 1554, was catalogued by Otto Struve, but has faded from view; thus it is called Struve’s Lost Nebula.

At lower left is the emission nebula Sharpless 2-239 embedded in the dense and brownish dust cloud LDN (Lynds Dark Nebula) 1551. It is dark indeed, but not black. Like most dark nebulas it has some warm colour.

Orion the Hunter

The most photogenic constellation is surely Orion the Hunter. It is filled with a rich collection of nebulas, including the eponymous Orion Nebula, bright enough to be visible to the unaided eye in the Sword of Orion, and #42 in Charles Messier’s catalogue.

The largest feature (though one best seen only in photos) is the arc of Barnard’s Loop, a possible supernova remnant or stellar wind-blown bubble that encircles Orion. It is usually plotted on sky atlases as just an easternmost arc, though it extends down and below Orion, all the way over to blue Rigel at bottom right.

At top is the large circular emission nebula Sharpless 2-264, surrounding the head of Orion and the star Meissa and a loose open star cluster Collinder 69. The nebula has become known as the Angelfish Nebula. It sits above orange Betelgeuse (at left) and blue-white Bellatrix (at right), marking the shoulders of Orion.

As you can see, there’s a winter-full of targets to go after in Orion. However, in my tour, I focused on two areas of dust and reflection nebulas.

Messier 78 Area

This is the bright reflection nebula complex that includes Messier 78 (the largest blue-white nebula) and NGC 2071 above it. This is a stack of 30 x 4-minute exposures through the Astro-Tech AT90CFT refractor with its 0.8x Reducer for f/4.8, and with the filter-modified Canon R camera at ISO 1600. No filter was employed here.

This frames one of the other often-neglected nebulas in Orion, Messier 78, one of the objects catalogued by Charles Messier in the 1780s. His is the popular “hit list” of deep-sky targets for all amateur astronomers.

In this case, M78 is accompanied by another smaller reflection nebula, NGC 2071. They are set in a region of dark clouds of interstellar dust, and framed by the red-magenta arc of Barnard’s Loop, aka Sharpless 2-276. The small reflection nebula at upper left on the edge of another dark cloud is van den Bergh 62. The large faint star cluster left of centre on the edge of the Loop is NGC 2112.

The Witch Head Nebula

This is the reflection nebula called the Witch Head, but officially IC 2118 (also with the catalogue number NGC 1909), near the very bright star Rigel, at lower left in Orion. This is a stack of 29 x 6-minute exposures through the Astro-Tech AT90CFT refractor with its 0.8x Reducer for f/4.8, and with the filter-modified Canon R camera at ISO 800. No filter was employed here.

The hot, blue giant star at lower left is Rigel at the foot of Orion. It illuminates the dust cloud that forms the fanciful shape of the blue Witch Head Nebula, or IC 2118. The nebula is actually over the border in Eridanus the River. Some magenta emission nebulosity also populates the field in Orion.

Indeed, as the wide-field photo above attests, all of Orion is filled with some form of nebulosity, be it emission, reflection, or dark.

There’s much more to go after when exploring the nebulous and dusty realms of the Milky Way. The sky is filled with stardust. Indeed, we are made of it!

— Alan, November, 2023 / www.amazingsky.com