Hubble: Colliding Galaxy Pair Takes Flight (Arp 142)

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Hubble: Colliding Galaxy Pair Takes Flight (Arp 142)

Post by bystander » Thu Jun 20, 2013 5:10 pm

Colliding Galaxy Pair Takes Flight (Interacting Galaxies Arp 142)
NASA | STScI | HubbleSite | Hubble Heritage | 2013 Jun 20

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 stretched taffy.

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)

Hubble spots galaxies in close encounter
ESA/HEIC | Hubble Photo Release | 2013 Jun 20

Click to play embedded YouTube video.
The NASA/ESA Hubble Space Telescope has produced this vivid image of a pair of interacting galaxies known as Arp 142. When two galaxies stray too close to each other they begin to interact, causing spectacular changes in both objects. In some cases the two can merge — but in others, they are ripped apart.

Just below the centre of this image is the blue, twisted form of galaxy NGC 2936, one of the two interacting galaxies that form Arp 142 in the constellation of Hydra. Nicknamed "the Penguin" or "the Porpoise" by amateur astronomers, NGC 2936 used to be a standard spiral galaxy before being torn apart by the gravity of its cosmic companion.

The remnants of its spiral structure can still be seen — the former galactic bulge now forms the "eye" of the penguin, around which it is still possible to see where the galaxy's pinwheeling arms once were. These disrupted arms now shape the cosmic bird's "body" as bright streaks of blue and red across the image. These streaks arch down towards NGC 2936's nearby companion, the elliptical galaxy NGC 2937, visible here as a bright white oval. The pair show an uncanny resemblance to a penguin safeguarding its egg.

The effects of gravitational interaction between galaxies can be devastating. The Arp 142 pair are close enough together to interact violently, exchanging matter and causing havoc.

In the upper part of the image are two bright stars, both of which lie in the foreground of the Arp 142 pair. One of these is surrounded by a trail of sparkling blue material, which is actually another galaxy. This galaxy is thought to be too far away to play a role in the interaction — the same is true of the galaxies peppered around the body of NGC 2936. In the background are the blue and red elongated shapes of many other galaxies, which lie at vast distances from us — but which can all be seen by the sharp eye of Hubble.

This pair of galaxies is named after the American astronomer Halton Arp, the creator of the Atlas of Peculiar Galaxies, a catalogue of weirdly-shaped galaxies that was originally published in 1966. Arp compiled the catalogue in a bid to understand how galaxies evolved and changed shape over time, something he felt to be poorly understood. He chose his targets based on their strange appearances, but astronomers later realised that many of the objects in Arp's catalogue were in fact interacting and merging galaxies [1].

This image is a combination of visible and infrared light, created from data gathered by the NASA/ESA Hubble Space Telescope Wide Field Planetary Camera 3 (WFC3).
  1. Notes

    [*] The birth and evolution of various sets of merging galaxies was the subject of the book Cosmic Collisions – The Hubble Atlas of Merging Galaxies, produced by Springer and the European Southern Observatory. The book is illustrated with a range of stunning Hubble Space Telescope images.
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
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mikeabram

Re: Hubble: Colliding Galaxy Pair Takes Flight (Arp 142)

Post by mikeabram » Mon Jun 24, 2013 5:49 am

I am surprised by how little the companion eliptical galaxy is distorted by the encounter.

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Re: Hubble: Colliding Galaxy Pair Takes Flight (Arp 142)

Post by Beyond » Mon Jun 24, 2013 12:00 pm

Yeah. It's the same way in todays APOD.
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