Colliding Galaxy Pair Takes Flight
This striking NASA Hubble Space Telescope image, which shows what looks like
the profile of a celestial bird, belies the fact that close encounters between
galaxies are a messy business.
This interacting galaxy duo is collectively called Arp 142. The pair contains the
disturbed, star-forming spiral galaxy NGC 2936, along with its elliptical
companion, NGC 2937 at lower left.
Once part of a flat, spiral disk, the orbits of the galaxy's stars have become
scrambled due to gravitational tidal interactions with the other galaxy. This warps
the galaxy's orderly spiral, and interstellar gas is strewn out into giant tails like
Gas and dust drawn from the heart of NGC 2936 becomes compressed during the
encounter, which in turn triggers star formation. These bluish knots are visible
along the distorted arms that are closest to the companion elliptical. The reddish
dust, once within the galaxy, has been thrown out of the galaxy's plane and into
dark veins that are silhouetted against the bright starlight from what is left of the
nucleus and disk.
The companion elliptical, NGC 2937, is a puffball of stars with little gas or dust
present. The stars contained within the galaxy are mostly old, as evidenced by
their reddish color. There are no blue stars that would be evidence of recent star
formation. While the orbits of this elliptical's stars may be altered by the encounter,
it's not apparent that the gravitational pull by its neighboring galaxy is having
much of an effect.
Above the pair, an unrelated, lone, bluish galaxy, inconsistently cataloged as UGC 5130,
appears to be an elongated irregular or an edge-on spiral. Located 230 million light-years
away, this galaxy is much closer to us than the colliding pair, and therefore is not
interacting with them. It happens to lie along the same line of sight to foreground
Milky Way stars caught in the image.
Arp 142 lies 326 million light-years away in the southern constellation Hydra. It is
a member of the Arp catalog of peculiar galaxies observed by astronomer Halton C.
Arp in the 1960s.
This color image is a composite of Wide Field Camera 3 photos taken in green, visible,
and infrared light.
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)