Designation: NGC 346 Constellation: Tucana Visual magnitude: +10.3
Apparent size: 14′ x 11′ Diameter: 1149 light years. Distance: 200,000 light years
A large bright nebula, which is a long way away!
NGC 346 is located in another galaxy, the Small Magellanic Cloud (SMC). Many of the stars in this image are also in the SMC galaxy and one of the brightest of them all, HD 5980, is actually visible in the centre of this nebula.
Here is a blow up (in future: literally) of NGC 346 showing HD 5980:
HD 5980 is a multiple star system. To quote Wikipedia:
HD 5980 has at least three components amongst the most luminous stars known: the unusual primary has a Wolf–Rayet spectrum and has produced a luminous blue variable (LBV) outburst; the secondary, also a Wolf–Rayet star, forms an eclipsing spectroscopic binary with the primary star; and a more distant O-type supergiant is also likely to be a binary.
Gosh, a stellar system with two eclipsing Wolf-Rayet stars – plus an O-type supergiant which orbits the two WR stars. What a fascinating system that would be for a physicist to study!
Wolf-Rayets are extremely hot stars, up to about 210,000° K (our Sun is about 6000°K), depleted of hydrogen, and with very strong stellar winds. O type stars are also very hot. So all three stars have a short life-expectancy and each will ultimately go supernova. Not a good star system to reside in.
The SMC itself is one of our closest galaxies, gravitationally bound to the Milky Way. With a declination of -72°, it is only fully visible in the Southern Hemisphere, although theoretically visible as far north as +18°. It’s seen as a misty patch, about 5° wide (six Moon widths).
Here in SW Sydney the SMC is circumpolar (never sets) and looks like a piece of Milky Way that has broken away.
Also in image:
NGC 371, a hexagonal looking open cluster, with a diameter of 434 light years.
NGC 299, NGC 300, NGC 361, NGC 376, NGC 395, NGC 416.
IC 1611, IC1612.
See my above image with Astrometry.net annotated overlay.
Image & Processing:
|Location: outer suburban.
Conditions: clear sky, bright Moon
Sky brightness: 0.78 e/pixel/sec .
Image acquisition: SharpCap.
Image post-processing: GIMP.
|Telescope:||SkyWatcher Esprit||Type:||120 triplet refractor|
|Focal:||840 mm F/7||Mount:||SkyWatcher EQ6-R Pro|
|Camera:||ZWO ASI 071 MC Pro
||Type:||CMOS 28.4mm 16 Mpx
|Optical aids:||Flattener: Y; filter: LP||Guiding:||Yes/No|
|Polar aligning:||QHYCCD PoleMaster||Polar Error:||2’ 25”|
[ZWO ASI071MC Pro]
Auto Exp Target Brightness=100
Images © Roger Powell