LMC 1 Supergiant Shell

A colossal star cloud and a handful of small clusters

Image credit & copyright: Team Ciel Austral

RA: 05h 00m Dec: -65° 40′

Diameter: 2,400 light-years

OB Associations: LH 15

NGC Objects: NGC 1787

Supergiant Shell LMC 1

LMC 1 is located in the northwest corner of the LMC and has the simplest shell structure among all the Cloud’s supergiant shells. The faint H II region, N13, lies at the southeast shell rim and the very much fainter DEM L 35 at the southwest shell rim. The OB association LH 15 = NGC 1787 stretches from the southeast rim of the SGS northeast into its interior and is responsible for the ionization of the shell. The stars at the southeast end of LH 15 are younger and responsible for the photoionization of N13, whereas the stars at the northwest end of LH 15 are older and likely responsible for the formation of LMC 1’s large shell structure (Book et al, 2009).

Apart from a handful of small, faint clusters, LH 15 is all this SGS offers us. But what an offering! The star cloud occupies well over half a supergiant shell!

Low magnification overview

At ~1,100 x 600 light-years in size, it is impossible to visualise the volume of space occupied by the gargantuan star cloud, LH 15. Low magnification allows one to see exactly how dumbfoundingly huge it is – a gigantic, loose vaguely fan-shaped assortment of stars stretching 24′ in a NNW-SSE direction.

Although the ludicrously beautiful young globular cluster, NGC 1783, located 15′ south, is not associated with the SGS, its position and the arrangement of LH 15’s stars make it appear as if the stars have exploded out of the globular and been hurtled out in a wonderful spray of celestial sparks. Unusual and gorgeous!

LH 15 = NGC 1787 (Star Cloud)

RA 05 00 07.0 Dec -65 45 48 Mag 10.9 Size 24′ x 13′

16″ at 228x: This really is an enormous and stunning star cloud with around 50 resolved mag 11-13 stars arranged in beautiful patterns – chains, loops, and arcs – that are set against the gorgeous miasmic mist of unresolved stars dotted with the pinpricks of very small stars that dart in and out of view. Although the locations of the clusters one can visit in the star cloud are not too difficult to pinpoint because of the convenient star-hopping trails provided by LH 15’s beautiful star patterns, many of them (most of them) are extremely challenging to see because they are extremely small and faint. Time, excellent transparency and averted vision certainly help one find those that are little more than the very faintest droplets of pale starlight!

NGC 1787

SL 131 (Open Cluster)

RA 04 57 27.8 Dec -65 49 32 Mag – Size 0.9′ x 0.8′

16″ at 228x: Lying at the western end of an E-W arc of small stars open to the south, SL 131 appears very faint, irregular, ~15″ in diameter.

SL 131

LW 99 (Open Cluster)

RA 04 57 34.4 Dec -65 16 00 Mag 13.6 Size 1.4′ x 1.3′

16″ at 228x: This little cluster is easy to find thanks to mag 11.2 HD 270904 lying just southeast of it, but it is a very faint, round, washed-out glow, ~15″ in diameter. Averted vision helped.

LW 99

SL 142 (Open Cluster)

RA 04 58 15.0 Dec -65 23 27 Mag 14.5 Size 1.0′ x 0.9′

16″ at 228x: SL 142 appears as a very faint, round droplet of light, ~10″ in diameter.

SL 142

BSDL 359 (Association of Stars)

RA 04 59 11.0 Dec -65 43 12 Mag – Size –

16″ at 228x: BSDL 359 appears as a faint, round gathering of unresolved stars, of which only two are resolved.

BSDL 359

LW 108 (Open Cluster)

RA 04 59 19.2 Dec -65 33 3 Mag 13.8 Size 1.4′

16″ at 228x: LW 108, picked up with averted vision, appears as a very, very faint and very, very small, round glow.

LW 108

H88 77 (Open Cluster)

RA 05 00 09.0 Dec -65 45 00 Mag – Size –

16″ at 228x: H88 77 lies just north-northwest of mag 11 HD 270933, and but I was unable to pick it up with averted vision owing to the star intruding.

H88 77

BSDL 389 (Association of Stars)

RA 05 00 12.0 Dec -65 44 30 Mag – Size –

16″ at 228x: BSDL 389, lying just north-northwest of H88 77 appears, with averted vision, as an extremely small, and extremely faint, N-S slash of very pale starlight.

BSDL 389

LW 113 (Open Cluster)

RA 05 00 19.1 Dec -65 28 38 Mag – Size 0.8′

16″ at 228x: LW 113, picked up with averted vision, appears as a very, very faint, and very, very small daub of pale light just south of a small star.

LW 113

LW 114 (Open Cluster)

RA: 05 00 44.2 Dec: -65 27 18 Mag: 13.2 Size: –

16″ at 228x: Lying just south of a mag 12.7 star, LW 114 appears very faint, very small, round.

LW 114

HS 84 (Open Cluster)

RA 05 00 52.2 Dec -65 49 45 Mag – Size –

16″ at 228x: Observed a number of times, HS 84, was not only picked up with averted vision, but it also, each time I observed it appeared as an exceedingly faint and exceedingly small bead of pale light that trembled into sight and then trembled right out of sight… and stayed out of sight. Very odd!

HS 84

H88 91 (Open Cluster)

RA 05 01 21.7 Dec -65 55 13 Mag – Size 0.75′ x 0.65′

16″ at 228x: H88 91 remained resolutely out of sight.

H88 91

SL 178 (Open Cluster)

RA 05 01 45.2 Dec -65 49 27 Mag 10.9 Size 1.10′

16″ at 228x: SL 178 is a pretty little cluster, and very obvious at the eastern side of the star cloud – a small, bright smudge of unresolved stars, ~20′ in diameter, nestled up next to mag 10.9 HD 270958, lying on its eastern side.

Note: In some sources SL 178 is taken as NGC 1787.

SL 178

N13 (H II Region)

RA 05 43 08.0 Dec -68 58 18 Mag – Size 5.3′

16″ at 130x + UHC Filter: N13’s nebulosity is an extremely faint wispiness that some eyes and equipment may be able to pick up. Alas, I could see nothing of it with and without filters.