IC1396A
IC 1396A · a trunk of dust, shaped by starlight
The Elephant's Trunk is usually portrayed up close. This image does the opposite: it places the globule IC 1396A in the landscape that explains its shape in the first place — in landscape format across 3.63 × 2.57 degrees, or roughly 190 × 135 light-years at a distance of about 3,000 light-years. The trunk is no creature floating freely in space but the densest remnant of a molecular cloud in front of the red glow of the H II region IC 1396. And it has, as only the depth of this version reveals, a remarkable number of siblings.
It was taken through a dual-band filter that passes only the lines of Hα and [O III]. IC 1396 is almost pure Hα country — hence the deep red stage on which every dust silhouette stands as if punched out. Why emission nebulae glow in lines rather than in continuum is explained in the article on color.
The story began without any elephants. Edward Emerson Barnard found the extended nebulosity in 1893 on a seven-hour exposure taken with his Willard lens and called it, in 1894, a “magnificent specimen” of bright stars and nebula — of a trunk he wrote nothing. John Louis Emil Dreyer entered the find as IC 1396 in the first Index Catalogue in 1895; hence the “IC”. The A comes from the lettering with which Stuart Pottasch enumerated the bright-rimmed globules of the region in 1956. “Elephant's Trunk” is the later, vivid nickname for exactly this dark silhouette, not a historical catalog name.
The trunk is a shadow with a burning edge. Almost at the center of the image stands HD 206267, a hot multiple system with an O6 primary. Its ultraviolet light ionizes the hydrogen of the whole region. The head of IC 1396A lies only about 21 arcminutes, or 19 light-years, away in projection: the bright edge facing the star is an ionization front — gas on the illuminated side is ionized and streams away, while the dense core behind it blocks the light and remains standing as a dark pillar below the center of the image.
Inside the head sits the reflection nebula vdB 142 around HD 239710, whose Gaia parallax matches the distance of the cluster — the star is not merely in front of the cloud by chance, it belongs to it. Right beside it lies LkHα 349, a young system in the dark “eye” of the trunk; Spitzer has found further, optically hidden protostars there. A particularly lovely footnote: a 22 GHz water maser was detected in IC 1396A around a source of less than 0.1 solar luminosities — at the time the first at such a faint object.
The open cluster around the ionizing star is called Trumpler 37; it is so loose and large that it barely reads as a cluster in the image. Studies find an age gradient between HD 206267 and the globule, consistent with partly triggered star formation — a good indication, but no proof that every young star there was created by the front.
The famous trunk is only the lead character in a whole ensemble. At the southeastern edge stands the dragon-shaped dark cloud Barnard 163 with its offshoot B 163SW; in the southwest Barnard 365 and LDN 1085 fray the ring, and across the south runs an entire dark wall made of LDN 1087, LDN 1088 and Barnard 162 — including the bright-rimmed globule SFO 37, in which the Herbig-Haro complex HH 588 is building stars right now. At the northeastern edge the Pottasch globules IC 1396F and G continue the trunk's lettering, and Barnard 367 stands as a black island in the east. In the upper right of the image glows μ Cephei, Herschel's Garnet Star: a red supergiant among the largest stars known. This field is not a nebula with one curiosity in it, but a complete textbook chapter on dust at every level of detail.
Where in the sky
The rectangle is this image's real field of view, with its measured rotation — not a symbol. Constellation figures and star positions come from SIMBAD.
7 entries sit within 30° of each other here — click a field to jump to it.
Crops
The whole trunk
The trunk at full length — a pillar twenty light-years long
30.7′ × 54.5′·21h 34m 33.15s +57° 28′ 06.5″
The complete trunk, from the bright head to where it joins the parent cloud — a dust pillar some twenty light-years long. The edge facing the central star glows as a narrow bright rim: there the ionization front is eating into the gas, and the outflow from the evaporating surface shines by itself.
Behind it the core stays black. It is precisely this division of labor — burning outside, shielding inside — that is the reason the pillar exists at all: it is the shadow of its own dense head, in which the gas lies sheltered from the stellar wind.
Head of the trunk
The head with vdB 142 and LkHα 349 — stars in their birth cloud
13.4′ × 17.4′·21h 36m 34.98s +57° 29′ 53.2″
In the head of the globule, star formation is already under way: the bluish shimmer is the reflection nebula vdB 142 around HD 239710 — a star that, by its Gaia parallax, really does sit inside the cloud rather than by chance in front of it. Beside it opens the dark “eye”, a blown-out cavity in which the young system LkHα 349 sits.
What looks optically like two or three stars is a whole nursery in the infrared: Spitzer found further, deeply embedded protostars in the head — among them the source of a water maser which, at such low luminosity, was a first at the time.
Northern dark clouds
Barnard 161, LDN 1110 and LDN 1112 — the dust islands in the north
1.39° × 0.92°·21h 39m 44.10s +58° 19′ 58.0″
North of the center, several compact dust islands float in the sea of Hα: Barnard 161, the sharpest of them, plus the softer patches LDN 1110 and LDN 1112. Unlike the trunk they show hardly any bright rims — they lie farther from the ionizing source and are gnawed at correspondingly more gently.
Such clouds are the future in reverse time-lapse: small remnants of the same molecular cloud from which Trumpler 37 formed as well, not yet burned away by radiation, not yet turned into stars — raw material in a holding pattern.
HD 206267 & Tr 37
HD 206267 and Trumpler 37 — the engine of the nebula
54.5′ × 52.6′·21h 40m 01.70s +57° 21′ 18.1″
The least conspicuous crop contains the main character: HD 206267, a close multiple system with an O6 component whose ultraviolet radiation ionizes the entire nebula — more than a hundred light-years across — and makes it glow. Every bright globule rim in this image points at this single spot.
Spread around it lies the open cluster Trumpler 37, so far-flung that it barely registers as a cluster. The dark dent in the middle of the nebula is not a lack of material but the work of the star itself: its wind and its radiation have swept its own surroundings clean.
Globule IC 1396C
IC 1396C — Pottasch's less famous globule
35.3′ × 26.5′·21h 33m 01.86s +58° 02′ 22.2″
The trunk has an alphabet of siblings: in 1956 Stuart Pottasch lettered the bright-rimmed globules of the region one by one, and IC 1396C is one of the more imposing among them. It too carries the typical comet shape — bright head toward the ionizing source, dark tail pointing away from it.
The comparison with the great A is the real appeal here: same physics, smaller format. How long such a globule can still hold out against the central star is decided by its mass and its distance — the smaller letters of the catalog evaporated long ago.
B 367 & eastern edge
The eastern edge — a swarm of small globules around Barnard 367
59.9′ × 37.2′·21h 45m 35.69s +57° 12′ 45.1″
A detail of the eastern nebula edge — and a whole swarm of small globules: dark drops and fingers line up, among them the catalogued cloudlets LDN 1115 and LDN 1118, all shaped after the same pattern as the great trunk, only one size smaller.
The compact dark patch is Barnard 367, today also LDN 1113 — dense enough to swallow the Hα glow behind it completely. Historically a circle closes here: Barnard discovered the glowing large-scale region on his photographic plates in 1893 and, decades later, catalogued the individual dark clouds within it as well. Light and shadow of the same field both bear his name.
Barnard 163
Barnard 163 — the dragon in the southeast
20.8′ × 21.4′·21h 42m 06.25s +56° 43′ 50.4″
The most striking new silhouette of this version: Barnard 163, a dark cloud that pushes in front of the Hα glow like a dragon with its jaws torn open — the catalogs also list the area as LDN 1103 and 1104. Nearby lies the detached offshoot Barnard 163SW.
Unlike the trunk, the dragon shows almost no glowing edge: it stands farther from HD 206267 and is barely gnawed at any more. What you see is pure silhouette — dust that lies exactly between us and the nebula and simply swallows everything.
Globules F & G
IC 1396F and G — the letters carry on
42.0′ × 40.1′·21h 45m 08.12s +58° 15′ 13.3″
Pottasch's alphabet does not end at the famous A: at the northeastern edge stand the globules IC 1396F (with a bright rim and a tail) and IC 1396G — smaller editions of the same comet-shaped design, head toward the ionizing source, tail pointing away. Between them lies the dark cloud LDN 1130.
That it is precisely the inconspicuous letters which confirm the rule is the joke of this crop: the physics of the Elephant's Trunk is not a special case but a mass-produced article — it plays out at every dense clump that stands in the front's way.
B 365 & LDN 1085
Barnard 365 and LDN 1085 — where the ring frays
36.3′ × 42.4′·21h 33m 12.42s +56° 56′ 37.7″
At the southwestern edge the nebula ring falls apart into a web of dust fingers: Barnard 365 runs as a long dark crack through the glow, beside it lies the softer cloud LDN 1085. No sharp front is at work here any more — the structures interlock light and dark like cotton wool being pulled apart.
Such edges show what an H II region really is: not a balloon with a skin, but a glowing bubble eating its way through a clumpy molecular cloud — and in some places simply getting stuck.
Southern dark wall
The southern dark wall — LDN 1087, LDN 1088 and a star factory
0.96° × 1.28°·21h 38m 15.57s +56° 21′ 46.1″
Right across the south of the nebula runs a veritable wall of dark clouds: LDN 1087 and LDN 1088, plus Barnard 162 at the eastern end — the edge of the molecular cloud at which the Hα glow simply stops. What is black here is not empty but the densest material in the whole field.
And it is at work: the bright-rimmed globule SFO 37 holds the Herbig-Haro complex HH 588 — jets from freshly forming stars punching through their birth cloud. The dark wall is not a backdrop but the next generation of stars in the raw.
Acquisition and processing
The current version combines dual-band exposures acquired between 31 August and 10 September 2026 in Friedrichsdorf with a ZWO ASI2600MC Air on a William Optics RedCat 71. The WBPP provenance embedded in the image records 69 integrated frames: 1 × 180 s, 40 × 240 s and 28 × 300 s, totalling 18,180 s, or 5 h 3 min. The data include different gain settings; the earlier statement “40 of 40 at gain 100” applies only to the older image.
The published processing is the contrast-adjusted PiMagic version dated 12 September, measuring 5,887 × 4,166 pixels. Separate SDR and HDR sizes for the website are generated from the gain-map AVIF source.
The astrometric solution matches this exact version by verified file hash: 9,825 reference stars, residual error 1.09″, scale 2.2196″/pixel, field 3.630 × 2.569° and rotation 85.42°. North is approximately to the right. Object markers and crops use this current sky geometry.