LMC 4 Supergiant Shell

LMC 4 is one of the most remarkable places to explore with a telescope

Image credit & copyright: Team Ciel Austral

RA: 05h 32m Dec: -66° 10′

Diameter: 6,000 light-years

OB Associations: LH 51, 54, 60, 63, 65, 72, 76, 77, 82, 83, 84, 88, 91, 95

NGC Objects: NGC 1951, 1978, 2002, 2003, 2006, 2027, 2034, 2041, 2069

LMC 4 is so enormous that its incredibly rich southern periphery is on a separate page:

LMC 4 Southern Periphery

Supergiant Shell LMC 4 Cavity

The gargantuan supergiant shell LMC 4 is located in the northeast of the galaxy. With a diameter of 6,000 light-years, it is the largest supergiant shell in the Large Magellanic Cloud, and indeed as far as we know, in the Local Group itself. Its central cavity is mostly evacuated, and within it the most prominent OB association is LH 77 (also known as the Quadrant), an enormous and mysterious arc of stars. This association has an older stellar population, as it has already expelled its ambient gas, and has most likely contributed to the formation of LMC 4 (Book et al, 2009). Interestingly, LH 77 has two very much smaller associations, LH 65 and 84 within it.

Along the periphery of LMC 4 are several young OB associations still within H II regions. These include LH 83, LH 91, and LH 95 in the northeast, while along the southern rim lie LH 51; 54; 60; 63 in the Sextant, LH 76 in superbubble N57A, and LH 82 and LH 88 in the stunning Seagull Nebula. LH52 and 53 are located in the HII regions in the interaction zone between LMC 4 and LMC 5. And then, lying almost dead centre in the cavity is the mysterious OB association, LH 72 and H II region, N55 (the gorgeous Eighth-Note Nebula).

Low magnification overview

The size of this supergiant shell is beyond comprehension. Even in a pair of 10×50 binoculars its massive and dark cavern is beautifully obvious, its southern periphery a series of small glows, the enormous Quadrant a silvery arc, the N48 region on its western where it is colliding with its smaller neighbour, LMC 5, appearing as a shard-shaped glow.

A low magnification cruise around any supergiant shell is an extremely worthwhile observing experience, and around LMC 4, exceptionally so. Not only does it allow you to examine the locations of the OB associations and H II regions and contemplate the shell’s evolution across eons of time, but it is also tremendously enticing to look at the incredible diversity of gorgeous objects and wonder at the myriad secrets they are going to reveal with increasing magnification… the shimmering arc of stars that stretches from side to side towards its southern end… the eastern periphery’s patchy glows of nebulous light… the oddly shaped young globular cluster… the strange and beautiful nebula that resembles a musical note and literally takes centre stage… the plethora of clusters and countless stars scattered across its breadth… and then there’s the stunningly southern periphery alight with glowing superbubbles, star-forming regions, bubbles and stars.

The Quadrant

A gigantic, dazzling and mysterious arc of stars

The Quadrant

A gigantic, dazzling and mysterious arc of stars

The Quadrant

N55 - Eighth-Note Nebula

A beautiful and baffling nebula

N55

N55 - Eighth-Note Nebula

A beautiful and baffling nebula

N55

N63 & N63A

A superb little SNR in a lovely nebula

N63

N63 & N63A

A superb little SNR in a lovely nebula

N63

LH 95

A sparkling star-forming region

LH 95

A sparkling star-forming region

LH 95

SL 452 (Open Cluster)

RA 05 25 09.6 Dec -66 38 57 Mag – Size 0.8′ x 0.7′

16″ at 228x: SL 452 appears very faint, 20″ in diameter, round. No stars are resolved.

SL 452

NGC 1951 (Open Cluster)

RA 05 26 06.4 Dec -66 35 50 Mag 10.6 Size 1.9′

16″ at 228x: NGC 1951 appears as a bright, oval-shaped cluster, 50″ x 40″ in diameter, elongated N-S. Rich and smooth, it brightens to a small, bright core that is offset to the northwest of centre. A few faint stars are resolved on the southwest side and a couple more dance momentarily into view before disappearing back into the glow. Faint SL 465 lies just 1.8′ NNE.

NGC 1951

SL 465 (Open Cluster)

RA 05 26 14.1 Dec -66 34 0 Mag – Size –

16″ at 228x: Lying just 1.8′ NNE of NGC 1951 SL 465 appears as a very faint, round, hazy glow, ~40″ in diameter, round. No stars are resolved.

SL 465

SL 470 (Open Cluster)

RA 05 26 27.9 Dec -66 23 09 Mag 12.5 Size 1.0′ x 0.9′

16″ at 228x: A nice little cluster, SL 470 appears relatively bright, round, ~20″ in diameter, and with no stars resolved.

SL 470

SL 482 (Open Cluster)

RA 05 27 17.5 Dec -66 22 10 Mag – Size 0.7′ x 0.6′

16″ at 228x: SL 482 appears very bright but very small; it almost looks like a close double star with a little mistiness around it.

SL 482

SL 485 + BRHT 36b (Binary Cluster)

SL 485: RA 05 27 49.0 Dec -66 01 18 Mag – Size 0.9′ Sep 0.8′ PA 182°

BRHT 36b: RA 05 27 44.3 Dec -66 00 45 Mag – Size 1.2′ x 1.0′

16″ at 228x: This pair of clusters are relatively bright and actually quite pretty. BRHT 36b appears as a relatively bright chain of unresolved stars, albeit it has a slight grittiness to it. It is ~25″ in size, elongated NNW-SSE. SL 485, lying just off its SSE end, appears brightish, round, ~15″ in diameter, and with the slightest and faintest mistiness around it. No stars resolved.

SL 485 + BRHT 36b

NGC 1978 (Young Globular Cluster)

RA 05 28 45.3 Dec -66 14 12 Mag 10.7 Size 3.9′ x 2.7′ Age ~ 2 billion years

16″ at 228x: An absolutely gorgeous young globular cluster! It is very bright and the first thing one notices is its strangely elliptical shape, elongated NNW-SSE ~2.4′ x 1.5′. Very striking for a globular cluster. Its core is large and very bright, and it has a beautifully grainy halo in which a couple of mag 15 stars are resolved. It would be an impressive globular cluster in our Milky Way skies! It’s one of those objects one can’t help but return to for another look because its just such a gorgeous globular cluster in this thickly populated supergiant shell!

NGC 1978

SL 502 (Open Cluster)

RA 05 29 11.8 Dec -66 35 35 Mag 11.4 Size 1.5′ x 1.3′

16″ at 228x: SL 502 appears as a faint, irregular glow, ~15″ in diameter, with fuzzy edges. No stars resolved. It forms a nice pair with double star HRG 135 that lies 1.4′ S.

SL 502

HRG 135 (Double Star)

RA 05 29 12.8 Dec -66 36 52 Mag 1 9.5 Mag 2 9.5 Sep 1.8″ PA 23°

16″ at 228x: This pretty star forms an attractive pair with cluster SL 502 just 1.4′ N.

HRG 135

HS 326 (Open Cluster)

RA 05 29 38.0 Dec -66 45 43 Mag – Size 1.2′ x 1.0′

16″ at 228x: HS 326 is very faint; it doesn’t look like a cluster at all, more like a very small and vague brightening against the sky, slightly brighter in the centre. It forms an odd “pair” with SL 513 which lies 1.5′ E.

HS 326 (centre) + SL 523 (left)

SL 512 (Open Cluster)

RA 05 29 54.2 Dec -66 04 22 Mag – Size 0.7′

16″ at 228x: SL 512 appears very, very faint, and very, very small and round; just on the threshold of visibility.

SL 512

SL 513 (Open Cluster)

RA 05 29 57.8 Dec -66 45 21 Mag 12.4 Size 1.2′

16″ at 228x: SL 513 appears as a fairly faint, off-round glow, ~20″ in diameter, with no stars resolved. It makes an odd mis-matched “pair” with extremely faint HS 326 that lies 1.5′ W.

SL 523

SL 521 (Open Cluster)

RA 05 30 24.0 Dec-65 54 31 Mag 11.3 Size 0.7′

16″ at 228x: A lovely cluster; it is bright, 30″ in diameter, lying on the eastern side of an attractive triangle formed by a mag 12.7 star at the south vertex, a mag 13 at the southwest vertex, and a mag 14.2 star at the northwest vertex. There is a rich, gritty glow of unresolved stars, with two very small stars resolved.

SL 521

SL 524 (Open Cluster)

RA 05 30 51.0 Dec -66 20 00 Mag 12.5 Size 1.0′ x 0.9′

16″ at 228x: SL 524 appears as a bright, off-round droplet of stellar light with fuzzy edges, ~15″ in diameter.

SL 524

SL 527 (Open Cluster)

RA 05 3050.1 Dec -66 25 00 Mag – Size –

16″ at 228x: SL 527 appears as a faint, irregular, diffuse patch, ~20″ in diameter, with no stars resolved.

SL 527

NGC 2003 (Open Cluster)

RA 05 30 54.3 Dec -66 27 59 Mag 11.3 Size 2.1′

228x: NGC 2003 has a beautifully bright, rich and smooth core, 25″ in diameter, and slightly oval shaped, elongated ENE-WSW. It is surrounded by a thin, faint, hazy halo. No stars are resolved, but a couple of tiny stars pop in and out of view on the east side. Tiny cluster BSDL 2043 lies just off its west end; it appears like nothing more than a mag 13.5 star.

NGC 2003

HS 337 (Open Cluster)

RA 05 31 42.2 Dec -66 15 57 Mag – Size 0.7′ x 0.6′

16″ at 228x: Very small and very faint; cluster HS 337 looks like a faint and slightly out-of-focus star.

HS 337

SL 550 + BRHT 37b (Binary Cluster)

SL 550: RA 05 31 55.0 Dec -66 07 42 Mag – Size 1.2′ x 1.1′ Sep 0.62′ PA 103°

BRHT 37b: RA 05 32 00.0 Dec -66 07 54 Mag – Size 0.6′ x 0.5′

16″ at 228x: A small pair, with SL 550 appearing fairly bright, ~15″ in diameter, round; no resolution. Companion BRHT 37B, just east of SL 550, appears faint, stellar.

SL 550 + BRHT 37b

KMHK 1021 (Open Cluster)

RA 05 31 59.0 Dec -66 16 54 Mag – Size –

16″ at 228x: A very small, very faint cluster; it took averted vision to pick up.

KMHK 1021

HS 343 (Open Cluster)

RA 05 32 05.8 Dec -66 40 33 Mag – Size 1.0′

16″ at 228x: This cluster lies close to the base of a small triangle of bright stars whose apex points towards N55, the Eighth-Note Nebula. It is extremely faint and extremely small; one barely sees that it’s there.

HS 343

KMHK 1076 (Open Cluster)

RA 05 34 02.2 Dec -66 50 10 Mag – Size –

16″ at 228x: KMHK 1076 appears as a fuzzy, round, ~12″ in diameter, dab of unresolved stars.

KMHK 1076

HS 358 (Open Cluster)

RA 05 34 35.5 Dec -66 03 55 Mag – Size 1.0′

16″ at 228x: HS 358 appears like a wide pair of faint but smudgy stars, with a small faint star lying just south of it. Actually, quite nice.

HS 358

N62A-B + HS 268 (Emission Nebula + Open Cluster)

RA 05 34 40.0 Dec -66 14 19 Mag – Size –

16″ at 228x + UHC filter: Huge as N62A is, it’s so faint as to be invisible except for the most charming little shard of nebulosity. Even without a filter it is bright, ~50″ and very narrow, oriented E-W. It is almost the exact shape of an old-fashioned letter-opener – even with a slight pinch towards the west where the handle ends and the blade begins. The UHC filter certainly enhances the little nebula; its northern edge is strongly defined; its southern edge less so… it looks as if the letter opener is lying on a dark surface and sunlight is catching it along the edge of its blade. Lovely! (I confess it’s one of my favourite little nebulae in LMC 4.) Without the filter, BSDL 2393 lies roughly 1ʹ from the nebula’s west end; it is a lovely ~45″ knot of stars, elongated NNE-SSW, very obvious and very pretty. Four stars are resolved, among them the nebula’s ionising star, mag 12.5 HD 271363 (OB-type) is resolved on the western end of the cluster.

N62B is also huge but like N62A it’s so faint as to be invisible except for a slender, very faint, fuzzy N-S arc open to the west seen with the UHC filter. Without the filter a couple of very faint stars are involved with the arc and the nebula’s ionizing star, white mag 12.5 HD 271366 (OB-type) lies to the west of the arc, in the centre.

N62

LEDA 178603 (Background Galaxy)

RA 05 35 05.2 Dec -66 07 23 Mag – Size –

16″ at 228x: A background galaxy shining through the LMC’s largest SGS is such an odd thing to see! It appears as a faint, small, blurry, stellar droplet of galactic light. I wonder how far away it is?

LEDA 178603

KMHK 1120 (Open Cluster)

RA 05 35 49.0 -67 03 36 Mag – Size 0.6′

16″ at 228x: The other members of the cluster KMHK 1120 are completely washed out by its nice bright member, mag 11.8 OB-type star, HD 269844, which makes a really pretty pair with mag 11.3 B-type star, HD 269854 which lies 1′ SE. Mag 14.3 Wolf-Rayet star, Brey 59, lies 1′ NNE of the cluster.

KMHK 1120

NGC 2041 (Open Cluster)

RA 05 36 28.0 Dec -66 59 29 Mag 10.4 Size 0.7′

16″ at 228x: NGC 2041 lies off the eastern end of the Quadrant, where the mass of stars has lessened in a dramatic fashion, making this lovely little cluster quite an eye-catching sight. The cluster appears beautifully bright, 1′ in diameter, round. It increases steadily to a very small, bright core which continues to brighten to a stellar nucleus. Very pretty. It has slightly hazy edges but no stars are resolved.

NGC 2041

LH 91 + N61 (OB Assoc. + Emission Nebula)

RA 05 3636.0 Dec -66 27 12 Size 2ʹ

16″ at 228x: LH 91 is lovely! A dozen or so stars are resolved, and the half dozen brighter ones look like a miniature Southern Pleiades set against the lovely glow of unresolved stars and nebulosity. The small cluster, HS 268 lies at the east side of N61 and at 333x appears as a small, round smudge of stellar light. N61’s nebulosity without a filter is faint and very hazy and indistinct. It has a good response to the UHC filter, appearing round, patchy and with edges that fade away into the surrounding sky.

LH 91 + N61

N65 (Emission Nebula)

RA 05 37 03.0 Dec -66 39 46 Size 12.0′ x 9.0′

16″ at 228x + UHC filter: In the DSS image, vast circular N65 with brilliant mag 6.3 AZ Dor on its north end looks like a gorgeous celestial diamond ring, but alas the star’s brilliance completely washes out the nebulosity. I was hoping for a glimpse towards the southern end of the ring, but nothing but stars!

N65

HS 368 (Open Cluster)

RA 05 37 14.6 Dec -66 26 52 Mag – Size –

16″ at 228x: HS 368 appears as a very faint glow, ~15″ in diameter, but rather oddly for such a faint and inconspicuous cluster, it has a slightly gritty look.