Astronomers using the Advanced Camera for Surveys aboard the NASA/ESA Hubble Space Telescope have captured the best image so far of the spiral galaxy NGC 949.
This image shows the spiral galaxy NGC 949. Image credit: ESA / Hubble / NASA.
NGC 949, also known as UGC 1983 or PGC 9566, is a 12th-magnitude spiral galaxy located the constellation Triangulum, approximately 33.5 million light-years away.
It is a member of the NGC 1023 Group – a nearby, gravitationally-bound group of galaxies associated with the barred spiral galaxy NGC 1023.
The galaxy was discovered by Sir William Herschel on 21 September 1786.
It was one of about 3,000 objects Herschel catalogued as ‘nebulae’ during an intense and systematic deep sky survey, the results of which eventually formed the bulk of the New General Catalogue (NGC).
The new image from Hubble of NGC 949 allows astronomers to see a strange asymmetric alignment in the dark lanes of dust that snake across the galaxy.
The top-right half of the galaxy appears considerably more marbled with dust in this image; a curious observation explained by stars tending to favor locations towards the galaxy’s center, and dust preferring almost invariably to reside along the galactic plane.
When a galaxy is inclined as NGC 949 is, some regions — in this case the top-right — are tipped towards us and the light from the stars we see in these regions has had to travel through more dust.
This causes the light to appear redder – the result of the same process that gives solar light a red hue at dusk – or else disappear entirely, making the dust appear more prominent on that side of the galaxy.
In the part tipped away from us, the light from the stars has had to pass through much less dust to reach us, so it appears brighter, and the dust is much less prominent.
Were it possible to view this galaxy from the opposite side, the apparent alignment of the dust would be reversed.
