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Wednesday, April 20, 2011

NGC 3169 and NGC 3166: a pretty but disturbed pair of Galaxies

NGC 3169 and NGC 3166: a pretty but disturbed pair of Galaxies
Click on the image for full resolution (10.6 MB)

This image from the Wide Field Imager on the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile captures the pair of galaxies NGC 3169 (left) and NGC 3166 (right). These adjacent galaxies display some curious features, demonstrating that each member of the duo is close enough to feel the distorting gravitational influence of the other. The gravitational tug of war has warped the spiral shape of one galaxy, NGC 3169, and fragmented the dust lanes in its companion NGC 3166. This galactic grouping, found about 70 million light-years away in the constellation Sextans (The Sextant), was discovered by the English astronomer William Herschel in 1783. Modern astronomers have gauged the distance between NGC 3169 and NGC 3166 as a mere 50 000 light-years, a separation that is only about half the diameter of the Milky Way Galaxy. In such tight quarters, gravity can start to play havoc with galactic structure.
Spiral galaxies like NGC 3169 and NGC 3166 tend to have orderly swirls of stars and dust pinwheeling about their glowing centers. Close encounters with other massive objects can jumble this classic configuration, often serving as a disfiguring prelude to the merging of galaxies into one larger galaxy. So far, the interactions of NGC 3169 and NGC 3166 have just lent a bit of character. NGC 3169's arms, shining bright with big, young, blue stars, have been teased apart, and lots of luminous gas has been drawn out from its disc. In NGC 3166's case, the dust lanes that also usually outline spiral arms are in disarray. Unlike its bluer counterpart, NGC 3166 is not forming many new stars.
The full resolution image weighs 10.6 MB, so please be patient when downloading!
Credit: ESO/Igor Chekalin

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