A Galactic Traffic Jam
The barred spiral galaxy NGC 3887, seen here as viewed by the Wide Field Camera 3 aboard the NASA/ESA Hubble Space Telescope, lies over 60 million light-years away from us in the southern constellation of Crater (The Cup); it was discovered on 31 December 1785 by the German/British astronomer William Herschel.
Its orientation to us, while not exactly face-on, allows us to see NGC 3887’s spiral arms and central bulge in detail, making it an ideal target for studying a spiral galaxy’s winding arms and the stars within them.
The very existence of spiral arms was for a long time a problem for astronomers. The arms emanate from a spinning core and should therefore become wound up ever more tightly, causing them to eventually disappear after a (cosmologically) short amount of time. It was only in the 1960s that astronomers came up with the solution to this winding problem; rather than behaving like rigid structures, spiral arms are in fact areas of greater density in a galaxy’s disc, with dynamics similar to those of a traffic jam. The density of cars moving through a traffic jam increases at the centre of the jam, where they move more slowly. Spiral arms function in a similar way; as gas and dust move through the density waves they become compressed and linger, before moving out of them again.
Credit:ESA/Hubble & NASA, P. Erwin et al.
About the Image
Id: | potw2009a |
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Type: | Observation |
Release date: | 2 March 2020, 06:00 |
Size: | 973 x 1009 px |
About the Object
Name: | NGC 3887 |
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Type: | Local Universe : Galaxy : Type : Spiral |
Distance: | 60 million light years |
Constellation: | Crater |
Category: | Galaxies |
Wallpapers
Coordinates
Position (RA): | 11 47 4.56 |
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Position (Dec): | -16° 51' 16.62" |
Field of view: | 0.64 x 0.67 arcminutes |
Orientation: | North is 74.6° right of vertical |
Colours & filters
Band | Wavelength | Telescope |
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Optical g | 475 nm |
Hubble Space Telescope
WFC3 |
Optical I | 814 nm |
Hubble Space Telescope
WFC3 |
Infrared H | 1.6 μm |
Hubble Space Telescope
WFC3 |