LMC 7 Supergiant Shell

LMC 7 houses a star-forming complex that is considered a future rival to 30 Doradus

Image credit & copyright: Team Ciel Austral

RA: 04h 53m Dec: -69° 35′

Diameter: 2,600 light-years

OB Associations: LH 1, 2, 5

NGC Objects: NGC 1702, 1704, 1751, 1756

Supergiant Shell LMC 7

LMC 7 is open to the south with a dense ridge of ionized gas, the “New N79”, along the north. Abeit this H II region pales in comparison to optically bright star forming regions such as 30 Doradus or superbubble N11, it is absolutely fascinating to explore with a telescope. Harbouring the three enormous complexes N77 (N79 West), N79 (N79 South), and N83 (N79 East), this gigantic complex (spanning a whopping 1,630 light-years), is a highly efficient star forming engine.

The interior of the supergiant shell contains many filaments and clouds of diffuse emission most of which alas, are invisible to our telescopes, albeit there are a few very small and faint pools of nebulosity to observe. The shell also contains a vast 21ʹ x 15ʹ star cloud, filled to capacity with stars (as any self-respecting star cloud is) and containing among its stars three NGC open clusters along with six other small clusters.

Low magnification overview

A low magnification allows one to see the unusual structure of the supergiant shell. The southern side is open; its northern side is crowded with the vast “New 79” complex and the huge star cloud LH 8; and the rest of it is dotted with small clusters, among which is a young globular cluster to the south that appears as a small, round haze.

N79 can’t compete optically with either N11 or 30 Doradus, but it just as full of fascination, even at low magnification. N79 South and N79 East are very prominent as misty pools, while N79 West is a very patchy mist with the small, brightish glow of open cluster NGC 1698 anchoring the northwest corner of the entire complex. There is a tremendous contrast gain with all three components of the complex with the UHC filter, and a faint serpentine nebulosity can also be seen on the western side of N79 South.

The enormous star cloud LH 8 is just grand at low magnification! It’s a strange square-shaped cloud of stars that are scattered in uneven gatherings with dark star-less patches between them. The three NGC open clusters are very prominent – small but beautifully bright, round glows. SL 123, the northernmost of the cloud’s clusters is also quite prominet and a fainter round glow. The other clusters take a bit of work to distinguish from the rich carpet of stars, albeit they appear as little more than fattened-up stars themselves.

The New N79 Complex

A future rival to 30 Doradus

The New N79 Complex

A future rival to 30 Doradus

The New N79 Complex

N185 Superbubble

A phantom wisp superbubble

N185 Superbubble

A phantom wisp superbubble

N185 Superbubble

LH 8 Star Cloud

Full of stars and clusters

LH 8 Star Cloud

Full of stars and clusters

LH 8 Star Cloud

KMHK 119 (Open Cluster)

RA 04 49 16.0 Dec -69 52 30 Mag – Size 0.9′ x 0.7

16″ at 228x: This cluster appears as a very, very faint, small, and very diffuse glow picked up with averted vision.

KMHK 119

NGC 1702 (Open Cluster)

RA 04 49 26.0 Dec -69 51 06 Mag 12.5 Size 1.2′

16″ at 228x: This cluster forms the west vertex of an equilateral triangle with NGC 1704 lying 6′ NNE and the mag 7.2 star, HD 31518 lying 6.7′ WSW. It appears fairly bright, 40″ in diameter, round, with a rich, gritty glow in which half a dozen stars are resolved, among them a mag 14 star on its west side.

NGC 1702

KMHK 119 (Open Cluster)

RA 04 49 16.0 Dec -69 52 30 Mag – Size 0.9′ x 0.7′

16″ at 228x: Lying just 1.8′ SW of NGC 1702, this cluster appears as an extremely faint and feeble glow, ~ 10-12″ in diameter.

KMHK 119

NGC 1704 (Open Cluster)

RA 04 49 55.0 Dec -69 45 18 Mag 11.5 Size 1.7′ x 1.6′

16″ at 228x: NGC 1704 forms the north vertex of an equilateral triangle with NGC 1702 lying 6′ SSW and the mag 7.2 star, HD 31518 lying 6′ SE. It appears as a fairly bright E-W oval, 50″ x 30″ in size. A ~mag 13.5 star lies in the otherwise smooth core, and it has a nice hazy halo but no stars are resolved in it.

NGC 1704

SL 56 (Open Cluster)

RA 04 50 31.5 Dec -70 04 33 Mag 12.3 Size 1.0′ x 0.9′

16″ at 228x: Lying just 5.5′ S of the utterly gorgeous young globular, NGC 1711, this cluster appears as fairly bright, irregular, 25″ in diameter, with no stars resolved. A ~mag 13-13.5 star lies just off its north end.

SL 56

NGC 1711 (Young Globular Cluster)

RA 04 50 37.3 Dec -69 59 02 Mag 10.1 Size 3.5′ Age 68 million years

16″ at 228x: This very bright, large young globular is just gorgeous! Even at 90x its small round bright glow is pretty impressive! At 228x it has a very bright, almost oval core extended ~40″ x 30″, and surrounded by a beautiful gritty halo that extends out to ~3′ in diameter and in which a number of mag 13+ stars are resolved.

NGC 1711

KMHK 156 (Open Cluster)

RA 04 51 00.0 Dec -70 01 24 Mag – Size 0.9′ x 0.8′

16″ at 228x: This small little cluster is completely overshadowed by the big, bright and beautiful young globular cluster, NGC 1711. It’s also a rather odd looking little cluster, appearing as a pair of 13 mag stars, oriented E-W and separated by 30″, with the very faintest smudge of unresolved star between them.

KMHK 156

SL 124 (Open Cluster)

RA 04 56 32.1 Dec -69 58 54 Mag – Size 65′ x 50′

16″ at 228x: SL 124 appears as a very faint and very small, off-round glow.

SL 124

SL 58 (Open Cluster)

RA 04 50 59.0 Dec -69 38 12 Mag 12.5 Size 1.1′ x 1.0′

16″ at 228x: SL 58 appears as a fairly faint, round glow, ~20″ in diameter. No stars are resolved.

SL 58

KMHK 207 (Open Cluster)

RA 04 53 00.0 Dec -69 37 24 Mag – Size 0.7′

16″ at 228x: KMHK 207 appears as a pair of mag 13 stars aligned E-W, the eastern star crisp, the western one smudgy-looking, and set against a very small and faint haze of unresolved stars.

KMHK 207

KMHK 229 (Open Cluster)

RA 04 53 51.6 Dec -69 34 14 Mag – Size 0.8′ x 0.7′

16″ at 228x: KMHK 229 appears as a mag 14 star surrounded by a very faint and small haze. Another mag 14 star lies very close SW. Another mag 15+ star lies off its NW side.

KMHK 229

NGC 1751 (Young Globular Cluster)

RA 04 54 12.0 Dec -69 48 24 Mag 11.7 Size 1.7′ Age –

16″ at 228x: This young globular cluster appears as a fairly faint, round, soft glow, ~1′ in diameter. Its small core appears as a slight brightening offset to the north, which makes the halo look strangely irregular, lopsided even. Two mag 15 stars are resolved at its edges.

NGC 1751

N88 (Low Excitation Blob)

RA 04 54 52.0 Dec -69 23 24 Mag – Size –

16″ at 228x + UHC filter: This is the first of two LEBs in LMC 7; the other, N90, lies just 8′ NNE. This tiny little blob takes a very careful look to find and examine! It looks like nothing more than a very small and faint mag 15 star lying ~15″ E of another tiny faint star, but the filter gives it a very slight sheen that indicates it is different to the star beside it.

N88

NGC 1756 (Open Cluster)

RA 04 54 53.0 Dec -69 42 54 Mag 11.7 Size 1.7′

16″ at 228x: NGC 1756 appears as a relatively bright, round, smooth and even glow, 45″ in diameter. No stars are resolved.

NGC 1756

SL 106 (Open Cluster)

RA 04 55 06.0 Dec -69 40 24 Mag 11.3 Size 1.7′ x 1.5′

16″ at 228x: SL 106 appears as a bright, irregular, and smooth glow, ~25″ in diameter. A small star lies off its southeast side, and another off its northwest side.

SL 106

N90 (Low Excitation Blob)

RA 04 55 25.0 Dec -69 16 06 Mag – Size 0.4′

16″ at 228x + UHC filter: A blob is always a delight! And this little LEB appears as a faint and hazy glow, ~15″ in diameter, with hazily crisp edges.

N90

BSDL 248 (Open Cluster)

RA 04 55 27.0 Dec -69 38 42 Mag – Size –

16″ at 228x: BSDL 248 appears as a faint and small, N-S smudge of unresolved stars in which a ~mag 14 star is resolved towards the centre.

BSDL 248

SL 110 (Open Cluster)

RA 04 55 43.4 Dec -69 09 30 Mag 13.3 Size 0.8′ x 0.7′

16″ at 228x: SL 110 appears as a very faint, round glow, not quite stellar, but almost.

SL 110

SL 112 (Open Cluster)

RA 04 55 53.0 Dec -69 42 54 Mag – Size –

16″ at 228x: This is an interesting little cluster. It appears as a faint, irregular glow of unresolved stars, ~25″ in diameter, with a mag 13.2 star resolved on its southern end. What appears to be a fuzzyish mag 13 star on its northern end is in fact another cluster, BSDL 268.

SL 112

SL 114 (Open Cluster)

RA 04 56 10.8 Dec -69 15 02 Mag 11.5 Size 0.8′ x 0.7′

16″ at 228x: Situated in a triangle of mag 12-13 stars, SL 114 appears fairly bright, ~25″ in diameter, irregular and with two resolved stars. Mag 11.9 blue supergiant HD 268809 lies at or just off its south end. Another mag 12.5 star, HD 268807, is resolved at the north end, surrounded by the soft haze of unresolved stars.

SL 114 + R156

N93 (H II Region)

RA 04 56 58.4 Dec -69 12 45 Mag – Size 2.1′ x 1.8′

16″ at 228x: + UHC filter: N93 appears as an extremely faint, extremely diffuse, small glow, just barely brighter than the background, and picked up with averted vision. Without the UHC filter a mag 12.1 star lies to its north.

N93

SL 124 (Open Cluster)

RA 04 56 31.0 Dec -69 58 54 Mag – Size 0.7′ x 0.5′

16″ at 228x: SL 124 appears faint, round, 20″ in diameter, no stars resolved. A pretty quartet of mag 13, 14+ stars lies 1.4′ SW; it looks like a slightly off kilter, miniature Southern Cross on the New Zealand flag.