APOD and General Astronomy Discussion Forum
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This unusual lenticular galaxy, known as NGC 1947, has lost almost all the gas and dust from its signature spiral arms, which used to orbit around its centre. Discovered almost 200 years ago by James Dunlop, a Scottish-born astronomer who later studied the sky from Australia, NGC 1947 can only be seen from the southern hemisphere, in the constellation Dorado (The Dolphinfish).
Residing around 40 million light-years away from Earth, this galaxy shows off its structure by backlighting its remaining faint gas and dust disc with millions of stars. In this picture, taken with the NASA/ESA Hubble Space Telescope, the faint remnants of the galaxy’s spiral arms can still be made out in the stretched thin threads of dark gas encircling it. Without most of its star-forming material, it is unlikely that many new stars will be born within NGC 1947, leaving this galaxy to continue fading with time.
AnnESA/Hubble wrote:
The magnificent central bar of NGC 2217 (also known as AM 0619-271) shines bright in the constellation of Canis Major (The Greater Dog), in this new image taken by the NASA/ESA Hubble Space Telescope. Roughly 65 million light-years from Earth, this barred spiral galaxy is a similar size to our Milky Way at 100 thousand light-years across. Many stars are concentrated in its central region forming the luminous bar, surrounded by a set of tightly wound spiral arms.
The central bar in these types of galaxies plays an important role in their evolution, helping to funnel gas from the disc into the middle of the galaxy. The transported gas and dust are then either formed into new stars or fed to the supermassive black hole at the galaxy's centre.
